Photo-detecting apparatus with low dark current

Abstract

To provide a photo-detecting apparatus.SOLUTION: A photo-detecting apparatus includes: a carrier conducting layer having a first surface; an absorption region doped with a first dopant having a first conductivity type and a first peak doping concentration; and a first electrode and a second electrode both formed over the first surface of the carrier conducting layer. The carrier conducting layer is doped with a second dopant having a second conductivity type and a second peak doping concentration, the carrier conducting layer includes a material different from a material of the absorption region, and the carrier conducting layer is in contact with the absorption region to form at least one heterointerface. A ratio between the first peak doping concentration of the absorption region and the second peak doping concentration of the carrier conducting layer is equal to or greater than 10.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 62 / 892,551, filed August 28, 2019, U.S. Provisional Patent Application No. 62 / 899,153, filed September 12, 2019, U.S. Provisional Patent Application No. 62 / 929,089, filed October 31, 2019, and U.S. Provisional Patent Application No. 63 / 053,723, filed July 20, 2020, each of which is incorporated by reference herein in its entirety. [Background technology]

[0002] Photodetectors can be used to detect optical signals and convert them into electrical signals that can be further processed by other circuitry. Photodetectors can be used in consumer electronics, image sensors, high-speed optical receivers, data communications, direct / indirect time-of-flight (TOF) ranging or imaging sensors, medical devices, and many other suitable applications. Summary of the Invention [Means for solving the problem]

[0003] FIELD OF THE DISCLOSURE The present disclosure relates generally to light detection devices and imaging systems including light detection devices.

[0004] According to another embodiment of the present disclosure, there is provided a photodetector device comprising: an absorber region including a first dopant having a first peak doping concentration; and a substrate supporting the absorber region, the substrate including a second dopant having a second peak doping concentration less than the first peak doping concentration, and the absorber region comprising a material different from that of the substrate.

[0005] According to an embodiment of the present disclosure, there is provided a photodetector device comprising: a carrier conduction layer having a first surface and a second surface; an absorber region in contact with the carrier conduction layer and configured to receive an optical signal and generate photocarriers in response to the optical signal, the absorber region being doped with a first dopant having a first conductivity type and a first peak doping concentration, the carrier conduction layer being doped with a second dopant having a second conductivity type and a second peak doping concentration, the carrier conduction layer comprising a material different from that of the absorber region, the carrier conduction layer being in contact with the absorber region to form at least one heterointerface, wherein a ratio between the doping concentration of the absorber region and the doping concentration of the carrier conduction region at the at least one heterointerface is 10 or greater; and a first electrode and a second electrode formed on the same side of the carrier conduction layer.

[0006] According to an embodiment of the present disclosure, there is provided a photodetector device, the photodetector device comprising: a carrier conduction layer having a first surface and a second surface; and an absorption region in contact with the carrier conduction layer and configured to receive an optical signal and generate photocarriers in response to the optical signal, the absorption region doped with a first dopant having a first conductivity type and a first peak doping concentration, the carrier conduction layer doped with a second dopant having a second conductivity type and a second peak doping concentration, the carrier conduction layer comprising a material different from that of the absorption region, and the carrier conduction layer forming at least one heterointerface. and a second doped region in the carrier conduction layer in contact with the absorber region to provide a fourth dopant having the same conductivity type as the first conductivity type and a fourth peak doping concentration higher than the first peak doping concentration, the fourth dopant having the same conductivity type as the first conductivity type and a fourth peak doping concentration higher than the first peak doping concentration.

[0007] According to an embodiment of the present disclosure, there is provided a photodetector device, the photodetector device comprising: a carrier conduction layer having a first surface and a second surface; and an absorber region in contact with the carrier conduction layer and configured to receive an optical signal and generate photocarriers in response to the optical signal, the absorber region doped with a first dopant having a first conductivity type and a first peak doping concentration, the carrier conduction layer doped with a second dopant having a second conductivity type and a second peak doping concentration, the carrier conduction layer comprising a material different from that of the absorber region, the carrier conduction layer in contact with the absorber region to form at least one heterointerface, a ratio between a doping concentration of the absorber region and a doping concentration of the carrier conduction region at the at least one heterointerface is 10 or greater, a ratio between the first peak doping concentration of the absorber region and a second peak doping concentration of the carrier conduction region is 10 or greater, and at least 50% of the absorber region has a doping concentration of 1×10 or greater. 16 cm -3 The first dopant is doped at a doping concentration equal to or greater than the first dopant.

[0008] According to an embodiment of the present disclosure, a light detection device is provided. a first electrode formed on the first surface of the carrier conduction layer and electrically coupled to the carrier conduction layer, the first electrode being separated from the absorber region and configured to collect a portion of the photocarriers; and a second electrode formed on the first surface of the carrier conduction layer and electrically coupled to the absorber region, the first electrode being separated from the absorber region and configured to collect a portion of the photocarriers.

[0009] According to another embodiment of the present disclosure, there is provided a photodetector device, the photodetector device comprising: a substrate having a first surface and a second surface; and an absorber region on the first surface of the substrate configured to receive an optical signal and generate photocarriers in response to the optical signal, the absorber region being doped with a first dopant having a first conductivity type and a first peak doping concentration, and the substrate being doped with a second dopant having a second conductivity type and a second peak doping concentration, the substrate comprising a material different from that of the absorber region, and the substrate doping the absorber region to form at least one heterointerface. and a second electrode formed on the first surface of the substrate and electrically coupled to the absorber region, the first electrode being separated from the absorber region and configured to collect a portion of the photocarriers. According to another embodiment of the present disclosure, a photodetector device is provided.The photodetector apparatus includes a photodetector device, the photodetector device configured to receive an optical signal and generate photocarriers in response to the optical signal, the absorber region being doped with a first dopant having a first conductivity type and a first peak doping concentration, and a protective layer over the absorber region having a first surface and a second surface opposite the first surface, the protective layer being doped with a second dopant having a second conductivity type and a second peak doping concentration, the protective layer comprising a material different from a material of the absorber region, and the protective layer having at least one heterointerface. a protection layer in contact with the absorber region to form a peak doping concentration of the protection layer, wherein a ratio between a first peak doping concentration of the absorber region and a second peak doping concentration of the protection layer is 10 or greater, or a ratio between the doping concentration of the absorber region and a doping concentration of the protection layer at at least one heterointerface is 10 or greater; a first electrode formed on a first surface of the protection layer and electrically coupled to the protection layer, the first electrode being separated from the absorber region and configured to collect a portion of the photocarriers; and a second electrode formed on the first surface of the protection layer and electrically coupled to the absorber region.

[0010] According to another embodiment of the present disclosure, there is provided a photodetector apparatus, the photodetector apparatus comprising: a carrier conduction layer having a first surface and a second surface; and an absorber region in contact with the carrier conduction layer and configured to receive an optical signal and generate photocarriers in response to the optical signal, the absorber region being doped with a first dopant having a first conductivity type and a first peak doping concentration, the carrier conduction layer being doped with a second dopant having a second conductivity type and a second peak doping concentration, the carrier conduction layer comprising a material different from that of the absorber region, the carrier conduction layer being in contact with the absorber region to form at least one heterointerface; the absorber region, wherein a ratio between a doping concentration of the absorber region and a doping concentration of the carrier conduction layer at at least one heterointerface is 10 or greater, or a ratio between a first peak doping concentration of the absorber region and a second peak doping concentration of the carrier conduction layer is 10 or greater; one or more switches electrically coupled to the absorber region and partially formed in the carrier conduction layer, each of the one or more switches comprising a control electrode and a readout electrode formed on the first surface and separated from the absorber region; and an electrode formed on the first surface and electrically coupled to the absorber region.

[0011] According to another embodiment of the present disclosure, there is provided a photodetector device, the photodetector device comprising: a carrier conduction layer having a first surface and a second surface; and an absorber region in contact with the carrier conduction layer and configured to receive an optical signal and generate photocarriers in response to the optical signal, the absorber region being doped with a first dopant having a first conductivity type and a first peak doping concentration, the carrier conduction layer being doped with a second dopant having a second conductivity type and a second peak doping concentration, the carrier conduction layer comprising a material different from that of the absorber region, the carrier conduction layer being in contact with the absorber region to form at least one heterointerface, and a doping concentration of the absorber region and a doping concentration of the carrier conduction layer at the at least one heterointerface being different from that of the absorber region. the ratio being 10 or greater, or the ratio between the first peak doping concentration of the absorber region and the second peak doping concentration of the carrier conduction layer being 10 or greater; one or more switches electrically coupled to the absorber region and partially formed in the carrier conduction layer, each of the one or more switches comprising a control electrode and a readout electrode formed on the same side of the carrier conduction layer; a second doped region in the carrier conduction layer in contact with the absorber region, the second doped region having the same conductivity type as the first conductivity type and doped with a fourth dopant having a fourth peak doping concentration higher than the first peak doping concentration; and an electrode electrically coupled to the second doped region.

[0012] According to another embodiment of the present disclosure, there is provided a photodetection apparatus comprising: a carrier conduction layer having a first surface and a second surface; an absorber region in contact with the carrier conduction layer and configured to receive an optical signal and generate photocarriers in response to the optical signal, the absorber region doped with a first dopant having a first conductivity type and a first peak doping concentration, the carrier conduction layer doped with a second dopant having a second conductivity type and a second peak doping concentration, the carrier conduction layer comprising a material different from that of the absorber region, the carrier conduction layer in contact with the absorber region to form at least one heterointerface, wherein a ratio between the doping concentration of the absorber region and the doping concentration of the carrier conduction layer at the at least one heterointerface is 10 or greater, or a ratio between the first peak doping concentration of the absorber region and the second peak doping concentration of the carrier conduction layer is 10 or greater; and one or more switches electrically coupled to the absorber region and partially formed in the carrier conduction layer. The photodetector device further comprises one or more readout circuits electrically connected to each switch, the one or more readout circuits comprising a voltage-controlled transistor between the transfer transistor and the capacitor.

[0013] According to another embodiment of the present disclosure, there is provided a photodetector device comprising: an absorber region doped with a first dopant having a first peak doping concentration; and a carrier conduction layer in contact with the absorber region, the carrier conduction layer comprising a conduction region doped with a second dopant having a second peak doping concentration lower than the first peak doping concentration, the carrier conduction layer comprising or consisting of a material different from that of the absorber region, and the conduction region having a depth of less than 5 μm.

[0014] According to another embodiment of the present disclosure, there is provided a photodetector device comprising: an absorber region doped with a first dopant having a first peak doping concentration; a first contact region having a conductivity type; a second contact region having a conductivity type different from that of the first contact region; a charge region having the same conductivity type as that of the first contact region and a portion thereof between the first and second contact regions; and a substrate supporting the absorber region, wherein the substrate includes the second dopant having a second peak doping concentration less than the first peak doping concentration, and the absorber region comprises a material different from that of the substrate.

[0015] According to another embodiment of the present disclosure, there is provided a photodetector device comprising: a substrate; an absorber region supported by the substrate and doped with a first dopant having a first conductivity type; a plurality of first contact regions formed in the substrate, each having a conductivity type different from the first conductivity type; a second doped region formed in the absorber region, the second doped region having the same conductivity type as the first conductivity type; and a plurality of third contact regions formed in the substrate, each having the same conductivity type as the first conductivity type, the first contact regions being arranged along a first plane and the third contact regions being arranged along a second plane different from the first plane. In one embodiment, a plurality of multiplication regions are formed between the plurality of third contact regions and the plurality of first contact regions.

[0016] According to another embodiment of the present disclosure, there is provided a photodetector device comprising: an absorber region; a first contact region having a conductivity type; a second contact region in the absorber region having a conductivity type different from that of the first contact region; a charge region having the same conductivity type as that of the first contact region, the charge region being closer to the second contact region than the first contact region; and a substrate supporting the absorber region, wherein the charge region and the first contact region are formed in the substrate. The photodetector device further comprises a correction element integrated with the substrate for correcting the location at which multiplication occurs in the substrate.

[0017] According to another embodiment of the present disclosure, there is provided a photodetector device comprising a substrate, an absorber region supported by the substrate, a first contact region formed on the substrate and having a conductivity type different from that of the first contact region, a second contact region formed on the absorber region and having a conductivity type different from that of the first contact region, and a charge region formed on the substrate and having a conductivity type similar to that of the first contact region, the charge region having a depth less than that of the first contact region. In some embodiments, the charge region has a depth between that of the second contact region and that of the first contact region.

[0018] According to another embodiment of the present disclosure, there is provided a photodetection apparatus comprising: a substrate having a first surface and a second surface; and an absorber region on the first surface of the substrate configured to receive an optical signal and generate photocarriers in response to the optical signal, the absorber region being doped with a first dopant having a first conductivity type and a first peak doping concentration, the substrate being doped with a second dopant having a second conductivity type and a second peak doping concentration, the substrate comprising a material different from that of the absorber region, the substrate being in contact with the absorber region to form at least one heterointerface, wherein a ratio between the doping concentration of the absorber region and the doping concentration of the substrate at the at least one heterointerface is 10 or greater, or a ratio between the first peak doping concentration of the absorber region and the second peak doping concentration of the substrate is 10 or greater, and the substrate further comprising a waveguide configured to guide and confine an optical signal propagating through a defined region of the substrate to couple the optical signal to the absorber region.

[0019] According to another embodiment of the present disclosure, there is provided a photodetection apparatus comprising: a carrier conduction layer having a first surface and a second surface; an absorber region in contact with the carrier conduction layer and configured to receive an optical signal and generate photocarriers in response to the optical signal, the absorber region doped with a first dopant having a first conductivity type and a first peak doping concentration, the carrier conduction layer doped with a second dopant having a second conductivity type and a second peak doping concentration, the carrier conduction layer comprising a material different from that of the absorber region, the carrier conduction layer in contact with the absorber region to form at least one heterointerface, a ratio between the doping concentration of the absorber region and the doping concentration of the carrier conduction layer at the at least one heterointerface being 10 or greater; and N switches electrically coupled to the absorber region and partially formed in the carrier conduction layer. The photodetection apparatus further includes Y control signals different from each other and electrically coupled to the photodetection device, where Y≦N, and Y is a positive integer. Each of the control signals controls one or more of the switches of the light-detecting device.

[0020] According to another embodiment of the present disclosure, there is provided a photodetector device comprising: an absorber region including a first dopant having a first peak doping concentration; and a substrate supporting the absorber region, the substrate including a second dopant having a second peak doping concentration lower than the first peak doping concentration; the absorber region including a material having a bandgap smaller than the bandgap of a material of the substrate; a buried field region across an interface between the substrate and the absorber region, a first width of the buried field region in the substrate greater than a second width of the buried field region in the absorber region such that dark current is predominantly generated from the substrate.

[0021] According to another embodiment of the present disclosure, there is provided a photodetector device comprising: an absorber region configured to receive an optical signal and generate photocarriers having a first polarity and a second polarity; a lightly doped region configured to receive a portion of the photocarriers having the first polarity from the absorber region; and a gain component configured to receive a portion of the photocarriers having the first polarity from the lightly doped region and generate an electrical signal having a second polarity, wherein a number of charges in the electrical signal having the second polarity generated by the gain component is greater than a number of charges in the photocarriers generated by the absorber region.

[0022] According to another embodiment of the present disclosure, there is provided a photodetector device comprising: an absorber region doped with a first dopant type having a first peak doping concentration, the absorber region configured to receive an optical signal and generate photocarriers having a first polarity and a second polarity; a lightly doped region doped with a second dopant type having a second peak doping concentration, the lightly doped region receiving a portion of the photocarriers having the first polarity from the absorber region, the first dopant type being different from the second dopant type; and a gain component configured to receive a portion of the photocarriers having the first polarity from the lightly doped region and generate an electrical signal having the second polarity, wherein a ratio of the first peak doping concentration of the absorber region to the second peak doping concentration of the lightly doped region is 10 or greater, and a number of charges of the electrical signal having the second polarity generated by the gain component is greater than a number of photocarrier charges generated by the absorber region.

[0023] According to another embodiment of the present disclosure, a method is provided for amplifying an optical carrier received by a photodetector device having a gain component. The method includes receiving an optical signal at an absorption region to generate photocarriers having a first type and photocarriers having a second type; steering the first type photocarriers to a gain region; and generating an amplified electrical signal having the second type, wherein generating the amplified electrical signal includes applying a first voltage to an emitter electrode of the gain component; applying a second voltage to a collector electrode of the gain component such that a forward bias is created across a p-n junction between the emitter region of the gain component and a lightly doped region of the gain component, and such that a reverse bias is created across the p-n junction between the collector region of the gain component and the lightly doped region of the gain component; receiving the first type carriers in the lightly doped region of the gain component to increase the forward bias between the emitter region and the lightly doped region; and collecting the second type carriers emitted from the emitter region by the collector region as an amplified electrical signal.

[0024] According to another embodiment of the present disclosure, there is provided a photodetector device comprising: an absorber region configured to receive an optical signal and generate photocarriers having a first polarity and a second polarity; a substrate configured to receive a portion of the photocarriers having the first polarity from the absorber region; and one or more switches electrically coupled to the absorber region and at least partially formed in the substrate, each of the switches comprising a gain component configured to receive a portion of the photocarriers having the first polarity and generate an electrical signal having a second polarity, wherein a number of charges in the electrical signal having the second polarity generated by the gain component is greater than a number of charges in the photocarriers generated by the absorber region.

[0025] According to an embodiment of the present disclosure, there is provided an imaging system, comprising: a transmitting unit capable of emitting a light beam; and a receiving unit comprising an image sensor comprising a light detection device.

[0026] These and other objects of the present disclosure will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

[0027] The foregoing aspects and many of the attendant advantages of the present application will become more readily appreciated as the same become better understood by reference to the following detailed description when taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0028] [Figure 1A] 1 is a cross-sectional view of a light-sensing device according to an embodiment. [Figure 1B] 1 is a cross-sectional view of a light-sensing device according to an embodiment. [Figure 1C] 1 is a cross-sectional view of a light-sensing device according to an embodiment. [Figure 1D] 1 is a cross-sectional view of a light-sensing device according to an embodiment. [Figure 2A] 1 is a cross-sectional view of a light-sensing device according to an embodiment. [Figure 2B] 1 is a cross-sectional view of a light-sensing device according to an embodiment. [Figure 2C] 1 is a cross-sectional view of a light-sensing device according to an embodiment. [Figure 2D] 1 is a cross-sectional view of a light-sensing device according to an embodiment. [Figure 2E] 1 is a schematic diagram of a circuit of a photodetector device according to an embodiment. [Figure 2F] 1 is a schematic diagram of a circuit of a photodetector device according to an embodiment. [Figure 3A] FIG. 2 is a top view of a light-sensing device according to an embodiment. [Figure 3B]3B is a cross-sectional view taken along line AA' in FIG. 3A according to an embodiment. [Figure 4A] FIG. 2 is a top view of a light-sensing device according to an embodiment. [Figure 4B] 4B is a cross-sectional view taken along line AA' in FIG. 4A according to an embodiment. [Figure 4C] 4B is a cross-sectional view taken along line BB' in FIG. 4A according to an embodiment. [Figure 5A] FIG. 2 is a top view of a light-sensing device according to an embodiment. [Figure 5B] 5B is a cross-sectional view taken along line AA' in FIG. 5A according to an embodiment. [Figure 5C] FIG. 5B is a cross-sectional view taken along line BB' in FIG. 5A according to an embodiment. [Figure 6A] FIG. 2 is a top view of a light-sensing device according to an embodiment. [Figure 6B] FIG. 6B is a cross-sectional view taken along line AA' in FIG. 6A according to an embodiment. [Figure 6C] FIG. 2 is a top view of a light-sensing device according to an embodiment. [Figure 6D] FIG. 6D is a cross-sectional view taken along line AA' in FIG. 6C according to an embodiment. [Figure 6E] FIG. 6D is a cross-sectional view taken along line BB' in FIG. 6C according to an embodiment. [Figure 6F] FIG. 2 is a top view of a light-sensing device according to an embodiment. [Figure 6G] FIG. 2 is a top view of a light-sensing device according to an embodiment. [Figure 7A] FIG. 2 is a top view of a light-sensing device according to an embodiment. [Figure 7B] 7B is a cross-sectional view taken along line AA' in FIG. 7A according to an embodiment. [Figure 7C] FIG. 2 is a top view of a light-sensing device according to an embodiment. [Figure 7D] FIG. 2 is a top view of a light-sensing device according to an embodiment. [Figure 7E]FIG. 2 is a top view of a light-sensing device according to an embodiment. [Figure 8A] FIG. 2 is a top view of a light-sensing device according to an embodiment. [Figure 8B] 8B is a cross-sectional view taken along line AA' in FIG. 8A according to an embodiment. [Figure 8C] FIG. 2 is a top view of a light-sensing device according to an embodiment. [Figure 8D] FIG. 2 is a top view of a light-sensing device according to an embodiment. [Figure 8E] FIG. 2 is a top view of a light-sensing device according to an embodiment. [Figure 9A] 1 is a schematic diagram of a circuit of a photodetector device according to an embodiment. [Figure 9B] 1 is a schematic diagram of a circuit of a photodetector device according to an embodiment. [Figure 10A] 1 is a cross-sectional view of a light-sensing device according to an embodiment. [Figure 10B] FIG. 2 is a top view of a light-sensing device according to an embodiment. [Figure 10C] FIG. 10C is a cross-sectional view taken along line AA' in FIG. 10B according to an embodiment. [Figure 10D] FIG. 2 is a top view of a light-sensing device according to an embodiment. [Figure 10E] FIG. 10D is a cross-sectional view taken along line AA' in FIG. 10D according to an embodiment. [Figure 10F] FIG. 10D is a cross-sectional view taken along line BB' in FIG. 10D according to an embodiment. [Figure 10G] 1 is a cross-sectional view of a light-sensing device according to an embodiment. [Figure 10H] 1 is a cross-sectional view of a light-sensing device according to an embodiment. [Figure 10I] 1 is a cross-sectional view of a light-sensing device according to an embodiment. [Figure 11A] 1 is a cross-sectional view of a light-sensing device according to an embodiment. [Figure 11B] FIG. 2 is a top view of a light-sensing device according to an embodiment. [Figure 11C]FIG. 11C is a cross-sectional view taken along line AA' in FIG. 11B according to an embodiment. [Figure 11D] FIG. 2 is a top view of a light-sensing device according to an embodiment. [Figure 11E] FIG. 11D is a cross-sectional view taken along line AA' in FIG. 11D according to an embodiment. [Figure 12A] 1 is a cross-sectional view of an absorption region of a photodetector device according to an embodiment. [Figure 12B] 1 is a cross-sectional view of an absorption region of a photodetector device according to an embodiment. [Figure 12C] 1 is a cross-sectional view of an absorption region of a photodetector device according to an embodiment. [Figure 13A] FIG. 2 is a top view of a light-sensing device according to an embodiment. [Figure 13B] FIG. 2 is a top view of a light-sensing device according to an embodiment. [Figure 14A] 1 is a cross-sectional view of a portion of a light-sensing device according to an embodiment. [Figure 14B] 1 is a cross-sectional view of a photodetector device taken along a line passing through a second doped region 108 according to an embodiment. [Figure 14C] FIG. 2 is a top view of a light-sensing device according to an embodiment. [Figure 14D] FIG. 14D is a cross-sectional view taken along line AA' in FIG. 14C according to an embodiment. [Figure 14E] FIG. 14D is a cross-sectional view taken along line BB' in FIG. 14C according to an embodiment. [Figure 14F] 1 is a cross-sectional view of a light-sensing device according to an embodiment. [Figure 14G] FIG. 2 is a top view of a light-sensing device according to an embodiment. [Figure 14H] FIG. 14C is a cross-sectional view taken along line AA' in FIG. 14G according to an embodiment. [Figure 14I] FIG. 14C is a cross-sectional view taken along line BB' in FIG. 14G according to an embodiment. [Figure 14J] FIG. 2 is a top view of a light-sensing device according to an embodiment. [Figure 14K] FIG. 14J is a cross-sectional view taken along line AA' in FIG. 14J according to an embodiment. [Figure 14L] FIG. 14J is a cross-sectional view taken along line BB' in FIG. 14J according to an embodiment. [Figure 15A] FIG. 10 is a diagram of an example of a gain component with two terminals. [Figure 15B] FIG. 10 is a diagram of an example of a gain component with two terminals. [Figure 15C] FIG. 10 is a diagram of an example of a gain component with two terminals. [Figure 15D] FIG. 10 is a diagram of an example of a gain component with two terminals. [Figure 16A] FIG. 10 is a diagram of an example of a gain component with three terminals. [Figure 16B] FIG. 10 is a diagram of an example of a gain component with three terminals. [Figure 16C] FIG. 10 is a diagram of an example of a gain component with three terminals. [Figure 16D] FIG. 10 is a diagram of an example of a gain component with three terminals. [Figure 17A] 1 is a diagram of an example of a photodetector device that can be used as a CMOS image sensor. [Figure 17B] 1 is a diagram of an example of a photodetector device that can be used as a CMOS image sensor. [Figure 17C] 1 is a diagram of an example of a photodetector device that can be used as a CMOS image sensor. [Figure 18A] 1 is a diagram of an example of a photodetector device that can be used as a CMOS image sensor. [Figure 18B] 1 is a diagram of an example of a photodetector device that can be used as a CMOS image sensor. [Figure 18C] 1 is a diagram of an example of a photodetector device that can be used as a CMOS image sensor. [Figure 19A] FIG. 1 is a diagram of a photodetector with gain. [Figure 19B] FIG. 1 is a diagram of a photodetector with gain. [Figure 20A] FIG. 1 is a top view of an example of a photodetector with gain. [Figure 20B] FIG. 1 is a top view of an example of a photodetector with gain. [Figure 21] FIG. 1 is a diagram of a photodetector with gain. [Figure 22A] FIG. 1 is a top view of an example of a photodetector with gain. [Figure 22B] FIG. 1 is a top view of an example of a photodetector with gain. [Figure 23A] FIG. 1 is a top view of an example of a photodetector with gain. [Figure 23B] FIG. 10 is a top view of another example of a photodetector with gain. [Figure 24A] FIG. 1 is a top view of an example of a photodetector with gain. [Figure 24B] FIG. 10 is a top view of another example of a photodetector with gain. [Figure 25A] 1 is a cross-sectional view of a portion of a light-sensing device. [Figure 25B] 1 is a cross-sectional view of a portion of a light-sensing device. [Figure 25C] 1 is a cross-sectional view of a portion of a light-sensing device. [Figure 26A] 1A and 1B are diagrams of example control regions of a light-sensing device according to an embodiment. [Figure 26B] 1A and 1B are diagrams of example control regions of a light-sensing device according to an embodiment. [Figure 26C] 1A and 1B are diagrams of example control regions of a light-sensing device according to an embodiment. [Figure 26D] 1A and 1B are diagrams of example control regions of a light-sensing device according to an embodiment. [Figure 27A] FIG. 1 is a block diagram of an example embodiment of an imaging system. [Figure 27B] FIG. 2 is a block diagram of an example receiving unit or controller. DETAILED DESCRIPTION OF THE INVENTION

[0029] As used herein, terms such as “first,” “second,” “third,” “fourth,” and “fifth” describe various elements, components, regions, layers, and / or sections, and these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms may only be used to distinguish one element, component, region, layer, or section from another. When used herein, terms such as “first,” “second,” “third,” “fourth,” and “fifth” do not imply any order or sequence unless clearly dictated by context. Terms such as “light detection,” “light sensing,” “light ray detection,” “light ray sensing,” and any other similar terms may be used interchangeably.

[0030] Spatial descriptions such as "above," "up," and "below" are directed with respect to the orientation shown in the figures unless otherwise specified. It should be understood that the spatial descriptions used herein are for illustrative purposes only, and that practical implementations of the structures described herein can be spatially arranged in any orientation or manner, provided that such arrangement does not contradict the advantages of the embodiments of the present disclosure.

[0031] As used herein, the term "intrinsic" means that the semiconductor material has not been intentionally doped with dopants.

[0032] FIG. 1A shows a cross-sectional view of a photodetector device 100a according to one embodiment. The photodetector device 100a includes an absorber region 10 and a substrate 20 supporting the absorber region 10. In one embodiment, the absorber region 10 is entirely embedded in the substrate 20. In one embodiment, the absorber region 10 is partially embedded in the substrate 20. In one embodiment, the photodetector device 100a includes at least one heterointerface between the absorber region 10 and a carrier conduction layer that includes or consists of a material different from the absorber region 10. In one embodiment, the carrier conduction layer is the substrate 20. For example, in one embodiment, the substrate 20 includes a first surface 21 and a second surface 22 opposite the first surface 21. In one embodiment, the absorber region 10 includes a first surface 11, a second surface 12, and one or more side surfaces 13. The second surface 12 is between the first surface 11 of the absorber region 10 and the second surface 22 of the substrate 20. The side surface 13 is between the first surface 11 of the absorber region 10 and the second surface 12 of the absorber region 10. At least one of the first surface 11, the second surface 12, and the side surface 13 of the absorber region 10 is in at least partial direct contact with the substrate 20, such that a heterointerface is formed between the absorber region 10 and the substrate 20.

[0033] In some embodiments, absorber region 10 is conductively doped and includes a first dopant having a first peak doping concentration. In some embodiments, absorber region 10 is configured to convert an optical signal, such as incident light, into an electrical signal. In some embodiments, the optical signal enters absorber region 10 at a first surface 21 of substrate 20. In some embodiments, the optical signal enters absorber region 10 at a second surface 22 of substrate 20. In some embodiments, absorber region 10 comprises a region of absorption AR defined by a light shield (not shown) that includes an optical window. Region of absorption AR is a virtual region that receives the optical signal entering through the optical window.

[0034] In one embodiment, the carrier conduction layer, which in one embodiment is the substrate 20, is doped with a conductivity type and includes a second dopant having a second peak doping concentration lower than the first peak doping concentration to reduce the dark current of the photodetector device 100a, which can improve the signal-to-noise ratio, sensitivity, and dynamic range characteristics of the photodetector device 100a.

[0035] In one embodiment, the first peak doping concentration is 1×10 16 cm -3 In one embodiment, the first peak doping concentration is 1×10 16 cm -3 and 1×10 20 cm -3 In some embodiments, the first peak doping concentration can be between 1×10 17 cm -3 and 1×10 20 cm -3 In some embodiments, the ratio of the first peak doping concentration to the second peak doping concentration is 10 or greater so that the photodetector device 100a can further achieve a low dark current. In some embodiments, the ratio of the first peak doping concentration to the second peak doping concentration is 100 or greater so that the photodetector device 100a can further achieve a low dark current and a high quantum efficiency simultaneously. In some embodiments, the conductivity type of the substrate 20 is p-type or n-type. In some embodiments, when the conductivity type of the substrate 20 is p-type using, for example, boron (B) and / or gallium (Ga) as a dopant, the second peak doping concentration is 1×10 or greater so that the photodetector device 100a can further achieve a low dark current and a high quantum efficiency simultaneously. 12 cm -3 and 1×10 16 cm -3 In one embodiment, when the conductivity type of the substrate 20 is n-type, for example using phosphorus (P) and / or arsenic (As) as dopants, the second peak doping concentration can be between 1×10 and 1×10 so that the photodetector device 100a can simultaneously achieve low dark current and high quantum efficiency. 14 cm-3 and 1×10 18 cm -3 It can be between.

[0036] In some embodiments, when the conductivity type of the carrier conduction layer, which in some embodiments is substrate 20, differs from the conductivity type of the absorber region 10 by having a second peak doping concentration in substrate 20 that is lower than the first peak doping concentration in absorber region 10, a depletion region crosses the heterointerface between substrate 20 and absorber region 10. When the photodetector device is in operation, a majority of the depletion region is in substrate 20. Stated differently, a first width of the depletion region in substrate 20 is greater than a second width of the depletion region in absorber region 10. In some embodiments, the ratio of the first width to the second width is greater than 10. In some embodiments, the first width of the buried field region in substrate 20 is greater than a second width of the buried field region in absorber region 10, such that the buried field region crosses the heterointerface between substrate 20 and absorber region 10 and the dark current is predominantly generated from substrate 20. As a result, the photodetector device can achieve a lower dark current. In some embodiments, the bandgap of the carrier conduction layer, which in some embodiments is substrate 20, is greater than the bandgap of absorber region 10.

[0037] In certain embodiments, having a second peak doping concentration of substrate 20 that is lower than the first peak doping concentration of absorber region 10 can reduce the electric field across absorber region 10, which in certain embodiments is the substrate 20, when the conductivity type of the carrier conduction layer is the same as the conductivity type of absorber region 10, such as when substrate 20 is p-type and absorber region 10 is p-type, thereby increasing the electric field across substrate 20. That is, there is a difference between the electric field across absorber region 10 and the electric field across substrate 20. As a result, the dark current of the photodetector device is further reduced. In certain embodiments, the bandgap of the carrier conduction layer, which is substrate 20, is larger than the bandgap of absorber region 10.

[0038] The carrier conduction layer, which in some embodiments is substrate 20, comprises a first doped region 102 separated from absorber region 10. First doped region 102 is doped with a conductivity type and includes a third dopant having a third peak doping concentration. The conductivity type of first doped region 102 is different from the conductivity type of absorber region 10. In some embodiments, the third peak doping concentration is higher than the second peak doping concentration. In some embodiments, the third peak doping concentration of first doped region 102 is 1×10 18 cm -3 and 5×10 20 cm -3 It can be between.

[0039] In one embodiment, at least 50% of the absorbent region 10 is 16 cm -3 In other words, at least half of the absorption region 10 is doped with a doping concentration of the first dopant of 1×10 or more. 16 cm -3 The absorber region 10 is intentionally doped with a first dopant having a doping concentration of 1×10 or more, for example, a ratio of the depth of the doped region in the absorber region 10 to the thickness of the absorber region 10 of 1 / 2 or more. In some embodiments, at least 80% of the absorber region 10 is intentionally doped with a first dopant having a doping concentration of 1×10 or more to further reduce the dark current of the photodetector device. 16 cm -3 For example, the ratio of the depth of the doped region in the absorber region 10 to the thickness of the absorber region 10 is 4 / 5 or greater.

[0040] In some embodiments, the carrier conducting layer may be significantly doped with a second dopant. For example, in some embodiments, at least 50% of the carrier conducting layer, which is substrate 20, may be significantly doped with a second dopant. 12 cm -3 In other words, at least half of the carrier conducting layer has a doping concentration of the second dopant of 1×10 or more. 12 cm -3The doped region is intentionally doped with a second dopant having a doping concentration of at least 1×10. For example, the ratio of the depth of the doped region in the substrate 20 to the thickness of the substrate 20 is at least 1 / 2. In some embodiments, at least 80% of the carrier conduction layer is at least 1×10. 12 cm -3 The doped region is intentionally doped with a second dopant having a doping concentration of at least 4 / 5, for example, a ratio of the depth of the doped region in the substrate 20 to the thickness of the substrate 20 of at least 4 / 5.

[0041] In some embodiments, the carrier conduction layer may be locally doped with a second dopant. For example, the carrier conduction layer, which in some embodiments is substrate 20, includes a conduction region 201. At least a portion of the conduction region 201 is between first doped region 102 and absorber region 10. In some embodiments, the conduction region 201 overlaps absorber region 10 and first doped region 102 to restrict the path of carriers generated from absorber region 10 and traveling toward first doped region 102. In some embodiments, the conduction region 201 has a depth measured from first surface 21 of substrate 20 along a direction D1 substantially perpendicular to first surface 21 of substrate 20. The depth is determined by measuring a dopant profile of the second dopant at a depth of 1×10 14 cm -3 From 1×10 15 cm -3 In some embodiments, the depth of the conduction region 201 is less than 5 μm to better transport carriers efficiently. In some embodiments, the conduction region 201 may overlap the entire first doped region 102. In some embodiments, the conduction region 201 has a width greater than the width of the absorption region 10.

[0042] In some embodiments, the first dopant and the second dopant are different, e.g., the first dopant is boron and the second dopant is phosphorus. In some embodiments, the doping concentration of the first dopant at the heterointerface between absorber region 10 and a carrier conduction layer, which in some embodiments is substrate 20, is greater than or equal to 1×10 16 cm -3In one embodiment, the doping concentration of the first dopant at the heterointerface is 1×10 16 cm -3 and 1×10 20 cm -3 Between or 1×10 17 cm -3 and 1×10 20 cm -3 In some embodiments, the doping concentration of the second dopant at the heterointerface is less than the doping concentration of the first dopant at the heterointerface. In some embodiments, the doping concentration of the second dopant at the heterointerface is less than 1×10 12 cm -3 and 1×10 17 cm -3 Between.

[0043] In some embodiments, the doping concentration of the first dopant at the heterointerface is sufficiently high to reduce the interface dark current generated at the heterointerface. As a result, the interface combination rate can be reduced, which in turn can result in lower dark current at the heterointerface. In some embodiments, the doping concentration of the second dopant at the heterointerface is lower than the doping concentration of the first dopant at the heterointerface, which also reduces the bulk dark current generated in the absorption region 10. In some embodiments, the photodetector device 100a includes a 10 4 The interface may have a recombination rate of less than cm / s.

[0044] In some embodiments, the ratio of the doping concentration of the first dopant to the doping concentration of the second dopant at the heterointerface is greater than or equal to 10, such that the photodetector device 100a can simultaneously achieve low dark current and high quantum efficiency at the heterointerface. In some embodiments, the ratio of the doping concentration of the first dopant to the doping concentration of the second dopant at the heterointerface is greater than or equal to 100, such that the photodetector device 100a can simultaneously exhibit even lower dark current and high quantum efficiency at the heterointerface.

[0045] In some embodiments, the second dopant may be in absorber region 10, but may be outside of absorber region 10 due to thermal diffusion or implantation residue, etc. In some embodiments, the first dopant may be in a carrier conduction layer, which in some embodiments is substrate 20, but may be outside of substrate region 20 due to thermal diffusion or implantation residue, etc.

[0046] In an embodiment, the first dopant may be introduced into absorber region 10 by any suitable process, such as in situ growth, ion implantation, and / or thermal diffusion.

[0047] In some embodiments, the second dopant may be introduced into substrate 20 by any suitable process, such as in situ growth, ion implantation, and / or thermal diffusion.

[0048] In some embodiments, the absorber region 10 is made of a first material or a composite of first materials. In some embodiments, the carrier conduction layer, which is the substrate 20, is made of a second material or a composite of second materials. The second material or composite of second materials is different from the first material or composite of first materials. For example, in some embodiments, the second material or composite of second materials has a different combination of elements than the first material or composite of first materials.

[0049] In some embodiments, the bandgap of the carrier conduction layer, which in some embodiments is substrate 20, is larger than the bandgap of absorber region 10. In some embodiments, absorber region 10 includes or consists of a semiconductor material. In some embodiments, substrate 20 includes or consists of a semiconductor material. In some embodiments, absorber region 10 includes or consists of a III-V semiconductor material. In some embodiments, substrate 20 includes or consists of a III-V semiconductor material. III-V semiconductor materials may include, but are not limited to, GaAs / AlAs, InP / InGaAs, GaSb / InAs, or InSb. For example, in some embodiments, absorber region 10 includes or consists of InGaAs, and substrate 20 includes or consists of InP. In some embodiments, absorber region 10 includes or consists of a semiconductor material containing a group IV element, such as Ge, Si, or Sn. In some embodiments, absorber region 10 includes, or consists of, a semiconductor material containing a group IV element, such as Si. x Ge y Sn 1-x-y Contains or Si x Ge y Sn 1-x-y where 0≦x≦1, 0≦y≦1, and 0≦x+y≦1. In one embodiment, the absorbing region 10 comprises Ge 1-a Sn a containing or Ge 1-a Sn a where 0≦a≦0.1. In one embodiment, the absorption region 10 comprises Ge x Si 1-x containing or Ge x Si 1-x where 0≦x≦1. In one embodiment, the absorber region 10, which is made of intrinsic germanium, is p-type due to material defects formed during the formation of the absorber region, where the defect density is 1×10 14 cm -3 From 1×10 16 cm -3In some embodiments, the carrier conduction layer, which in some embodiments is substrate 20, comprises or consists of a semiconductor material containing a group IV element, such as Ge, Si, or Sn. In some embodiments, substrate 20 is Si x Ge y Sn 1-x-y Contains or Si x Ge y Sn 1-x-y where 0≦x≦1, 0≦y≦1, and 0≦x+y≦1. In one embodiment, the substrate 20 is Ge 1-a Sn a containing or Ge 1-a Sn a where 0≦a≦0.1. In one embodiment, the substrate 20 is made of Ge x Si 1-x containing or Ge x Sn 1-x where 0≦x≦1. In one embodiment, the substrate 20, which is made of intrinsic germanium, is p-type due to material defects formed during the formation of the absorber region, where the defect density is 1×10 14 cm -3 From 1×10 16 cm -3 For example, in some embodiments, absorber region 10 comprises or consists of Ge and substrate 20 comprises or consists of Si.

[0050] In some embodiments, the conductivity type of absorber region 10 is p-type. In some embodiments, the first dopant is a Group III element. In some embodiments, the conductivity type of substrate 20 is n-type and the second dopant is a Group V element.

[0051] In some embodiments, the photodetector device includes a first electrode 30 electrically coupled to the first doped region 102. The first electrode 30 is separated from the absorber region 10. An ohmic contact can be formed between the first electrode 30 and the first doped region 102 depending on the material of the first electrode 30 and the third peak doping concentration of the first doped region 102. In some embodiments, the shortest distance d between the first electrode 30 and one of the side surfaces 13 of the absorber region can be between 0.1 μm and 20 μm. In some embodiments, the shortest distance d between the first electrode 30 and one of the side surfaces 13 of the absorber region can be between 0.1 μm and 5 μm. In some embodiments, the distance can be between 0.5 μm and 3 μm. If the distance d between the first electrode 30 and the side surface 13 is greater than 20 μm, the speed of the photodetector device 100a becomes slower. If the distance d between the first electrode 30 and the side surface 13 is less than 0.1 μm, the dark current of the photodetector device can be increased.

[0052] In one embodiment, the photodetector device 100a includes a second doped region 108 in the absorber region 10 near the first surface 11 of the absorber region 10. The second doped region 108 is doped with the same conductivity type as the conductivity type of the absorber region 10. In one embodiment, the second doped region 108 includes a fourth dopant having a fourth peak doping concentration that is higher than the first peak doping concentration. For example, the fourth peak doping concentration of the second doped region 108 is 1×10 18 cm -3 and 5×10 20 cm -3 In some embodiments, the second doped region 108 is not disposed on the first doped region 102 along the direction D1.

[0053] In some embodiments, the photodetector device 100a further comprises a second electrode 60 electrically coupled to the second doped region 108. An ohmic contact may be formed between the second electrode 60 and the second doped region 108 depending on the material of the second electrode 60 and the fourth peak doping concentration of the second doped region 108. The second electrode 60 is on the first surface 11 of the absorber region 10.

[0054] In one embodiment, the carrier conducting layer comprises a first surface and a second surface opposite first surface 21. First electrode 30 and second electrode 60 are both disposed on the first surface of the carrier conducting layer, i.e., first electrode 30 and second electrode 60 are disposed on the same side of the carrier conducting layer, which in one embodiment is substrate 20, which is beneficial for subsequent back-end fabrication processes.

[0055] The first doped region 102 and the second doped region 108 may be semiconductor contact regions. In some embodiments, depending on the circuitry electrically coupled to the first doped region 102 and the second doped region 108, carriers with a first type collected by one of the first doped region 102 and the second doped region 108 may be further processed, and carriers with a second type collected by the other doped region may be removed. As such, the photodetector device may have improved reliability and quantum efficiency.

[0056] In some embodiments, the absorber region 10 is doped with a graded doping profile. In some embodiments, the maximum concentration of the graded doping profile is greater than the second peak doping concentration of the second dopant. In some embodiments, the minimum concentration of the graded doping profile is greater than the second peak doping concentration of the second dopant. In some embodiments, the graded doping profile may be stepped from the first surface 11 of the absorber region 10 or from the second doped region 108 to the second surface 12 of the absorber region 10. In some embodiments, the graded doping profile may gradually decrease / increase or decrease / increase in a step-like manner depending on the direction of carrier movement. In some embodiments, the concentration of the graded doping profile gradually decreases / increases depending on the direction of carrier movement from the first surface 11 or from the second doped region 108 of the absorber region 10 to the second surface 12 of the absorber region 10. In one embodiment, the concentration of the graded doping profile gradually decreases / increases radially from the center of the first surface 11 or the second doped region 108 of the absorber region 10 to the second surface 12 and side surface 13 of the absorber region 10, depending on the direction of carrier movement. For example, if the absorber region 10 spans the entire substrate 20, and the first doped region 102 is of n-type, carriers with a first type, such as electrons, move in the absorber region 10 substantially along the direction from the first surface 11 to the second surface 12, and the concentration of the graded doping profile of the first dopant, such as boron, gradually decreases from the first surface 11 or from the second doped region 108 of the absorber region 10 to the second surface 12 of the absorber region 10. In one embodiment, the concentration of the graded doping profile is gradually decreased / increased laterally from the edge of the first surface 11 or the second doped region 108 of the absorber region 10 to the side surface 13 of the absorber region 10, depending on the direction of carrier movement.

[0057] In one embodiment, the dark current of the photodetector device is, for example, 1×10 -12 A, i.e., less than about a few pA.

[0058] 1B shows a cross-sectional view of a light-sensing device according to an embodiment. The light-sensing device 100b in FIG. 1B is similar to the light-sensing device 100a in FIG. 1A. The differences are described below.

[0059] The photodetector device 100b further comprises another first doped region 104 in the substrate 20. The first doped region 104 is similar to the first doped region 102 as described in FIG. 1A. The first doped region 104 is separated from the absorber region 10. At least a portion of a conduction region 201 is also between the first doped region 104 and the absorber region 10. In some embodiments, the conduction region 201 partially overlaps the absorber region 10 and the first doped region 104 to restrict the path of carriers with a first type that are generated from the absorber region 10 and move toward the first doped region 104.

[0060] In some embodiments, the two first doped regions 104, 102 are separated from each other. In some embodiments, the two first doped regions 104, 102 may be a continuous region, such as a ring. The photo-detector device 100b further includes a third electrode 40 electrically coupled to the first doped region 104. In some embodiments, the first electrode 30 and the third electrode 40 may be electrically coupled to the same circuit.

[0061] In one embodiment, the dark current of the photodetector device 100b is, for example, 1×10 -12 A, i.e., less than about a few pA.

[0062] The comparative photodetector device has substantially the same structure as the photodetector device 100b in Fig. 1B, except that in the comparative photodetector device, the doping concentration of the absorption region 10 is equal to or less than the second peak doping concentration of the substrate 20, and the doping concentration of the second dopant at the heterointerface is equal to or greater than the doping concentration of the first dopant at the heterointerface.

[0063] Details of the comparative photodetector device and the photodetector device 100b are listed in Tables 1 and 2.

[0064] [Table 1]

[0065] [Table 2]

[0066] Referring to Table 3, compared to the comparative example, the photodetector device 100b may have a lower dark current, for example, at least two times lower, because the first peak doping concentration of the absorption region 10 in the photodetector device 100b is higher than the second peak doping concentration of the substrate 20.

[0067] [Table 3]

[0068] Another comparative photodetector device has substantially the same structure as the photodetector device 100b in FIG. 1B. The difference is that in the comparative photodetector device, the doping concentration of the absorption region 10 is equal to or less than the second peak doping concentration of the substrate 20, and the doping concentration of the second dopant at the heterointerface is equal to or greater than the doping concentration of the first dopant at the heterointerface. Details of the comparative photodetector device and the photodetector device 100b are listed in Tables 4 and 5.

[0069] [Table 4]

[0070] [Table 5]

[0071] Referring to Table 6, compared to another comparative example, the photodetector device 100b may have a lower dark current, for example, at least 20 times lower, because the first peak doping concentration of the absorption region 10 in the photodetector device 100b is higher than the second peak doping concentration of the substrate 20.

[0072] [Table 6]

[0073] 1C shows a cross-sectional view of a light-sensing device according to an embodiment. The light-sensing device 100c in FIG. 1C is similar to the light-sensing device 100a in FIG. 1A. The differences are described below.

[0074] The substrate 20 comprises a base portion 20a and an upper portion 20b supported by the base portion 20a. The upper portion 20b has a width smaller than that of the base portion 20a. The absorber region 10 is supported by the upper portion 20b of the substrate 20. The conductive region 201 is located in the upper portion 20b. The first doped region 102 is located in the base portion 20a. The first doped region 102 has a width larger than that of the upper portion 20b of the substrate 20, and therefore a portion of the first doped region 102 is not covered by the upper portion 20b. The second doped region 108 is disposed on the first doped region 102 along the direction D1, and the conductive region 201 is located between the first doped region 102 and the second doped region 108. Carriers of a first type, for example electrons, generated from the absorption region 10 travel along a direction D1 through the conduction region 201 towards the first doped region 102.

[0075] In some embodiments, the first electrode 30 may have any suitable shape, such as a ring from a top view of the photo-detector device. In some embodiments, the photo-detector device 100c includes two first electrodes 30 electrically coupled to the first doped region 102 and separated from each other. In some embodiments, the first electrodes 30 are disposed on opposite sides of the absorbing region 10.

[0076] In one embodiment, when impact ionization occurs based on a reverse bias voltage applied to the second doped region 108 and the first doped region 102, the photodetector device 100c may be an avalanche photodiode operated in a linear mode (reverse bias voltage<breakdown voltage) or a Geiger mode (reverse bias voltage>breakdown voltage), and a portion of the conduction region 201 between the absorber region 108 and the first doped region 102 may be a multiplication region. As such, the multiplication region may generate one or more additional charge carriers in response to receiving one or more carriers generated from the absorber region 10.

[0077] 1D shows a cross-sectional view of a light-sensing device according to an embodiment. The light-sensing device 100d in FIG. 1D is similar to the light-sensing device 100c in FIG. 1C. The differences are described below.

[0078] The photodetector device 100d further includes a charge layer 202 in the upper portion 20b of the substrate 20. The charge layer 202 is in direct contact with or overlaps a portion of the absorber region 10. The charge layer 202 has the same conductivity type as the absorber region 10. For example, if the absorber region 10 has a conductivity type of p, the charge layer 202 has a conductivity type of p. The charge layer 202 has a peak doping concentration that is higher than the second peak doping concentration of the conduction region 201 and lower than the first peak doping concentration of the absorber region 10. In one embodiment, the charge layer 202 has a thickness between 10 nm and 500 nm. The charge layer can reduce the electric field across the absorber region 10, thereby increasing the electric field across the conduction region 201. That is, there is a difference between the electric field across the absorber region 10 and the electric field across the conduction region 201. As a result, the photodetector device 100d is faster and more responsive, and the dark current of the photodetector device 100d is lower.

[0079] FIG. 2A shows a cross-sectional view of a photodetector device according to an embodiment. The photodetector device 200a in FIG. 2A is similar to the photodetector device 100a in FIG. 1A. Differences are described below. The second doped region 108 is located in the substrate 20. In other words, the fourth peak doping concentration of the second doped region 108 is located in the substrate 20. In an embodiment, the second doped region 108 is located below the first surface 21 of the substrate 20 and in direct contact with the absorber region 10. For example, the second doped region 108 may contact or overlap one of the side surfaces 13 of the absorber region 10. As a result, carriers generated in the absorber region 10 can travel from the absorber region 10 toward the second doped region 108 through the heterointerface between the absorber region 10 and the substrate 20. The second electrode 60 is located on the first surface 21 of the substrate 20.

[0080] By having the second doped region 108 in the substrate 20 instead of the absorbing region 10, the second electrode 60 and the first electrode 30 can both be formed above the first surface 21 of the substrate 20. Therefore, the height difference between the second electrode 60 and the first electrode 30 can be reduced, which allows subsequent fabrication processes to benefit from this design. Another advantage is that the area of ​​the absorbing region 10 that absorbs optical signals can be made larger.

[0081] 2B shows a cross-sectional view of a photodetector device according to an embodiment. The photodetector device 200b in FIG. 2B is similar to the photodetector device 200a in FIG. 2A. The differences are described below. The second doped region 108 may also contact or overlap the second surface 12 of the absorber region 10.

[0082] FIG. 2C shows a cross-sectional view of a photodetector device according to an embodiment. The photodetector device 200c in FIG. 2C is similar to the photodetector device 200b in FIG. 2B. The differences are described below. The absorber region 10 spans the entire substrate 20. A portion of the second doped region 108 is covered by the absorber region 10. In an embodiment, the width w2 of the second doped region 108 covered by the absorber region 10 can be greater than 0.2 μm. In an embodiment, the absorber region 10 has a width w1. The width w2 is 0.5w1 or less. This design allows two different types of carriers to move unimpeded from the absorber region 10 to the first doped region 102 and from the absorber region 10 to the second doped region 108, respectively.

[0083] FIG. 2D shows a cross-sectional view of a photodetector device according to an embodiment. The photodetector device 200d in FIG. 2D is similar to the photodetector device 200a in FIG. 2A. Differences are described below. The absorption region 10 is entirely embedded in the substrate 20. In an embodiment, the graded doping profile of the first dopant gradually decreases laterally from the side 13 near the second doped region 108 to the side 13 near the conductive region 201. FIG. 2E shows a schematic diagram of a photodetector apparatus according to an embodiment. The photodetector device 200e includes a pixel (not labeled) and a column bus electrically coupled to the pixel. The pixel includes a photodetector device and a readout circuit (not labeled) electrically coupled to the photodetector device and the column bus. The photodetector device can be any of the photodetector devices in FIGS. 1A-1D and 2A-2D, such as the photodetector device 100a in FIG. 1A. In some embodiments, the readout circuit (not labeled) and the column bus may be fabricated on another substrate and integrated / co-packaged with the photodetector device via die / wafer bonding or stacking. In some embodiments, the photodetector apparatus 200e includes a bonding layer (not shown) between the readout circuit and the photodetector device. The bonding layer may include any suitable material, such as an oxide, a semiconductor, a metal, or an alloy.

[0084] In an embodiment, a read circuit may be electrically coupled to the first doped region 102 or the second doped region 108 to process collected carriers with a first type, and a supply voltage or ground voltage may be applied to the other doped region to remove the other carriers with a second type opposite the first type.

[0085] For example, if the first doped region 102 is of n-type and the second doped region 108 is of p-type, a read circuit can be electrically coupled to the first doped region 102 to process the collected electrons for further application, and a ground voltage can be applied to the second doped region 108 to remove the holes. For another example, a read circuit can be electrically coupled to the second doped region 108 to process the collected holes for further processing, and a supply voltage can be applied to the first doped region 102 to remove the electrons.

[0086] In one embodiment, the read circuit may be a three-transistor configuration consisting of a reset gate, a source follower, and a select gate, a four-transistor configuration including an additional transfer gate, or any suitable circuit for processing the collected charge. For example, the read circuit may include a transfer transistor 171A, a reset transistor 141A, a capacitor 150A coupled to the reset transistor 141A, a source follower 142A, and a row select transistor 143A. Examples of the capacitor 150A include, but are not limited to, a floating diffusion capacitor, a metal-oxide-metal (MOM) capacitor, a metal-insulator-metal (MIM) capacitor, and a metal-oxide-semiconductor (MOS) capacitor.

[0087] The transfer transistor 171A transfers carriers from the photodetector device 100a to the capacitor 150A. In other words, the transfer transistor 171A is configured to output a photocurrent IA1 in response to a switching signal TG1. When the switching signal TG1 turns on the transfer transistor 171A, a photocurrent IA1 is generated.

[0088] At the start, the reset signal RST resets the output voltage VOUT1 to VDD. Then, when the switching signal TG1 turns on the transfer transistor 171A, a photocurrent IA1 is generated and the output voltage VOUT1 at the capacitor 150A decreases until the switching signal TG1 turns off the transistor 171A.

[0089] In another embodiment, the readout circuitry may be fabricated on another substrate and may be integrated / co-packaged with the light-detecting device 100a via die / wafer bonding or stacking.

[0090] In one embodiment, the light detection device is a CMOS image sensor operated at a frame rate of 1000 frames per second (fps) or less.

[0091] 2F shows a schematic diagram of a circuit of a photodetector according to one embodiment. The photodetector 200f is similar to the photodetector 200e in FIG. 2E. The differences are described below.

[0092] The read circuit of the photodetector device 200f further includes a voltage-control transistor 130A between the transfer transistor 171A and the capacitor 150A. The voltage-control transistor 130A is configured as a current buffer. Specifically, the output terminal of the voltage-control transistor 130A is coupled to the input terminal of the capacitor 150A, and the input terminal of the voltage-control transistor 130A is coupled to the output terminal of the transistor 171A. The control terminal of the voltage-control transistor 130A is coupled to a control voltage VC1.

[0093] Voltage-control transistor 130A is coupled between transfer transistor 171A and capacitor 150A, thereby isolating the output terminal of transfer transistor 171A from the input terminal of capacitor 150A. When voltage-control transistor 130A is operated in the sub-threshold or saturation region, the output terminal of transfer transistor 171A can be controlled or biased at a constant voltage VA1 to reduce the dark current generated by photodetector device 100a.

[0094] FIG. 3A shows a top view of a photodetector device according to an embodiment. FIG. 3B shows a cross-sectional view along line A-A' in FIG. 3A according to an embodiment. The photodetector device includes an absorber region 10 and a substrate 20 supporting the absorber region 10. The absorber region 10 is similar to the absorber region 10 described in FIG. 1A. The substrate 20 is similar to the substrate 20 described in FIG. 1A. Differences between the photodetector device 300a in FIG. 3A and the photodetector device 100a in FIG. 1A are described below. The photodetector device 300a includes a first switch (not labeled) and a second switch (not labeled) electrically coupled to the absorber region 10 and partially formed in a carrier conducting layer, which in an embodiment is the substrate 20. The first switch includes a control region C1 including a control electrode 340a. The first switch further includes a readout electrode 330a separated from the control electrode 340a. The second switch includes a control region C2 including a control electrode 340b. The second switch further comprises a readout electrode 330b separated from the control electrode 340b. In an embodiment, readout electrodes 330a, 330b and control electrodes 340a, 340b are formed on a first surface 21 of a substrate 20 and separated from the absorber region 10. In an embodiment, readout electrodes 330a and 330b are disposed on opposite sides of the absorber region 10. In an embodiment, the shortest distance between one of the control electrodes and one or more sides of the absorber region is between 0.1 μm and 20 μm.

[0095] In one embodiment, the photodetector apparatus includes a pixel including the photodetector device 300a as described above, and the pixel further includes two control signals, e.g., a first control signal and a second control signal, that control the control regions C1 and C2, respectively, to control the direction of movement of electrons or holes generated by absorbed photons in the absorber region 10. In one embodiment, the first control signal is different from the second control signal. For example, when a voltage is used, if one of the control signals is biased relative to the other control signal, an electric field is created between the two portions immediately below the control electrodes 340a and 340b, as in the absorber region 10, and free carriers in the absorber region 10 drift toward one of the portions immediately below the readout electrodes 330b and 330a, depending on the direction of the electric field. In one embodiment, the first control signal includes a first phase and the second control signal includes a second phase, where the first control phase does not overlap with the second control phase. In one embodiment, the first control signal is fixed at a voltage value V, and the second control signal alternates between voltage values ​​V±ΔV. In one embodiment, ΔV is generated by a varying voltage signal, for example a sinusoidal signal, a clock signal, or a pulse signal operated between 0 V and 3 V. The direction of the bias value determines the drift direction of carriers generated from the absorption region 10. The control signal is a modulation signal.

[0096] In one embodiment, the first switch comprises a first doped region 302a below the readout electrode 330a. The second switch comprises a first doped region 302b below the readout electrode 330b. In one embodiment, the first doped regions 302a, 302b are of a conductivity type different from that of the absorber region 10. In one embodiment, the first doped regions 302a, 302b comprise a dopant and a dopant profile with a peak dopant concentration. In one embodiment, the peak doping concentration of the first doped regions 302a, 302b is higher than the second peak doping concentration. In one embodiment, the peak dopant concentration of the first doped regions 302a, 302b depends on the material of the readout electrodes 330a, 330b and the material of the substrate 20, and may be, for example, 5×1018 cm -3 and 5×10 20 cm -3 The first doped regions 302a, 302b are carrier collecting regions for collecting carriers with a first type generated from the absorption region 10 under the control of two control signals.

[0097] In some embodiments, the absorption and carrier control functions, such as carrier demodulation and carrier collection, are performed in the absorption region 10 and the carrier conduction layer, which in some embodiments is the substrate 20, respectively.

[0098] In one embodiment, the photodetector device 300a may include a second doped region 108 and a second electrode 60 that are similar to the second doped region 108 and the second electrode 60, respectively, in FIG. 1A. The second doped region 108 is for removing carriers of a second type, opposite to the first type, that are not collected by the first doped regions 302a and 302b during operation of the photodetector device. In one embodiment, the control electrode 340a is symmetrical with the control electrode 340b about an axis passing through the second electrode 60. In one embodiment, the readout electrode 330a is symmetrical with the readout electrode 330b about an axis passing through the second electrode 60. The control electrodes 340a and 340b, the readout electrodes 330a and 330b, and the second electrode 60 are all disposed on a first surface of the carrier conducting layer. That is, the control electrodes 340a, 340b, the readout electrodes 330a, 330b, and the second electrode 60 are on the same side of the carrier conducting layer, which in some embodiments is the substrate 20.

[0099] In one embodiment, the substrate 20 of the photodetector device 300a includes a conductive region 201 similar to the conductive region 201 depicted in FIG. 1A . Differences are described below. In one embodiment, from a cross-sectional view of the photodetector device 300a, the width of the conductive region 201 can be greater than the distance between the two readout electrodes 330a, 330b. In one embodiment, the conductive region 201 overlaps the entire first doped regions 302a, 302b. In one embodiment, the width of the conductive region 201 can be less than the distance between the two readout electrodes 330a, 330b and greater than the distance between the two control electrodes 340a, 340b. In one embodiment, the conductive region 201 overlaps a portion of the first doped region 302a and a portion of the first doped region 302b. Because the conduction region 201 overlaps a portion of the first doped region 302a and a portion of the first doped region 302b, carriers with a first type generated from the absorption region 10 can be confined in the conduction region 201 and can move toward one of the first doped regions 302a, 302b under the control of two control signals. For example, if the first doped regions 302a, 302b are n-type, the conduction region 201 is n-type, and the second doped region 108 is p-type, electrons generated from the absorption region 10 can be confined in the conduction region 201 and can move toward one of the first doped regions 302a, 302b under the control of the two control signals, and holes can move toward the second doped region 108 and can be further removed by the circuit.

[0100] In some embodiments, the light detection device comprises a pixel array including a plurality of repeating pixels, hi some embodiments, the pixel array may be a one-dimensional or two-dimensional array of pixels.

[0101] The comparative photodetector device has substantially the same structure as the photodetector device 300a in FIG. 3A, except that in the comparative photodetector device, the doping concentration of the absorption region 10 is less than or equal to the second peak doping concentration of the substrate 20, and the doping concentration of the second dopant at the heterointerface is greater than or equal to the doping concentration of the first dopant at the heterointerface.

[0102] Details of the comparative photodetector device and the photodetector device 300a are listed in Tables 7 and 8.

[0103] [Table 7]

[0104] [Table 8]

[0105] Referring to Tables 9 and 10, compared to the comparative example, the photodetector device 300a may have a lower dark current, for example, at least 100 times lower, because the first peak doping concentration of the absorption region 10 in the photodetector device 300a is higher than the second peak doping concentration of the substrate 20.

[0106] [Table 9]

[0107] [Table 10]

[0108] In some embodiments, a voltage may be applied to the second electrode 60. In some embodiments, the voltage applied to the second electrode 60 may reduce leakage current between the second doped region 108 and the control regions C1 and C2. In some embodiments, the voltage is between the voltages applied to the control electrodes 340a and 340b when operating the photodetector device 300a.

[0109] FIG. 4A shows a top view of a light-sensing device according to an embodiment. FIG. 4B shows a cross-sectional view along line A-A' in FIG. 4A according to an embodiment. FIG. 4C shows a cross-sectional view along line B-B' in FIG. 4A according to an embodiment. The light-sensing device 400a in FIG. 4A is similar to the light-sensing device 300a in FIG. 3A. Differences are described below.

[0110] 4A and 4B , the second doped region 108 is located in the substrate 20. In other words, the fourth peak doping concentration of the second doped region 108 is located in the substrate 20. The second doped region 108 is located below the first surface 21 of the substrate 20 and is in direct contact with the absorber region 10; for example, the second doped region 108 may contact or overlap one of the side surfaces 13 of the absorber region 10. As a result, carriers of the second type that are not collected by the first doped regions 302 a, 302 b can move from the absorber region 10 toward the second doped region 108 through the heterointerface between the absorber region 10 and the substrate 20.

[0111] For example, if the first doped regions 302a, 302b are of n-type, the conduction region 201 is of n-type, and the second doped region 108 is of p-type, electrons generated from the absorption region 10 are confined in the conduction region 201 and can move toward one of the first doped regions 302a, 302b based on the control of two control signals, and holes can move toward the second doped region 108 through the heterointerface between the absorption region 10 and the substrate 20 and can be further removed by the circuit.

[0112] The second electrode 60 is on the first surface 21 of the substrate 20. By having the second doped region 108 in the substrate 20 instead of the absorbing region 10, the second electrode 60, the readout electrodes 330a, 330b, and the control electrodes 340a, 340b can all be formed flush above the first surface 21 of the substrate 20. Therefore, the height difference between the second electrode 60 and any two of the four electrodes 330a, 330b, 340a, 340b can be reduced, thereby allowing subsequent fabrication processes to benefit from this design. Additionally, the area of ​​the absorbing region 10 that absorbs optical signals can be made larger.

[0113] FIG. 5A shows a top view of a photodetector device according to an embodiment. FIG. 5B shows a cross-sectional view along line A-A' in FIG. 5A according to an embodiment. FIG. 5C shows a cross-sectional view along line B-B' in FIG. 5A according to an embodiment. The photodetector device 500a in FIG. 4A is similar to the photodetector device 400a in FIG. 4A. The differences are described below. The readout electrodes 330a, 330b and the control electrodes 340a, 340b are disposed on the same side of the absorber region 10, which improves the contrast ratio of the photodetector device 400a because carriers are transported out of the absorber region 10 through one of the side surfaces 13. In an embodiment, the distance between the readout electrodes 330a, 330b along direction Y can be greater than the distance between the control electrodes 340a, 340b along direction Y. In an embodiment, the distance between the readout electrodes 330a, 330b along the Y direction may be substantially the same as the distance between the control electrodes 340a, 340b along the Y direction.

[0114] 6A shows a top view of a photodetector device according to an embodiment. FIG. 6B shows a cross-sectional view along line A-A' in FIG. 6A according to an embodiment. The photodetector device 600a in FIG. 6A is similar to the photodetector device 500a in FIG. 5A, for example, the readout electrodes 330a, 330b and the control electrodes 340a, 340b are located on the same side of the absorber region 10. Differences are described below.

[0115] 6A and 6B, the second doped region 108 is located on the substrate 20. In other words, the fourth peak doping concentration of the second doped region 108 is located on the substrate 20. The second doped region 108 is located below the first surface 21 of the substrate 20 and is in direct contact with the absorber region 10. For example, the second doped region 108 may contact or overlap one of the side surfaces 13 of the absorber region 10. As a result, carriers of the second type that are not collected by the first doped regions 302a and 302b can move from the absorber region 10 toward the second doped region 108 through the heterointerface between the absorber region 10 and the substrate 20. The second electrode 60 is located on the first surface 21 of the substrate 20. The absorber region 10 is located between the second electrode 60 and the electrodes 330a, 330b, 340a, and 340b.

[0116] By having the second doped region 108 in the substrate 20 instead of the absorbing region 10, the second electrode 60 and the four electrodes 330a, 330b, 340a, 340b can all be formed flush above the first surface 21 of the substrate 20. Therefore, the height difference between any two of the second electrode 60 and the four electrodes 330a, 330b, 340a, 340b can be reduced, which will benefit subsequent fabrication processes from this design. Another advantage is that the area of ​​the absorbing region 10 that absorbs optical signals can be made larger.

[0117] In some embodiments, the conductive region 201 may overlap the entire first doped regions 302a, 302b.

[0118] FIG. 6C shows a top view of a photodetector device according to an embodiment. FIG. 6D shows a cross-sectional view along line A-A' in FIG. 6C according to an embodiment. FIG. 6E shows a cross-sectional view along line B-B' in FIG. 6C according to an embodiment. The photodetector device 600c in FIG. 6C is similar to the photodetector device 600a in FIG. 6A, with the differences described below. The photodetector device 600c further includes a restriction region 180 between the absorber region 10 and the first doped regions 302a, 302b to cover at least a portion of the heterointerface between the absorber region 10 and the substrate 20. The restriction region 180 has a conductivity type different from that of the first doped regions 302a, 302b. In an embodiment, the restriction region 180 includes a dopant having a peak doping concentration of 1×10 16 cm -3 That is all. The conduction region 201 has a passage 181 formed through the restriction region 180 such that a portion of the conduction region 201 remains in direct contact with the absorption region 10 for transporting photocarriers from the absorption region 10 toward the first doped regions 302 a, 302 b. That is, the passage 181 is not covered by the restriction region 180. In some embodiments, the peak doping concentration of the restriction region 180 is lower than the second peak doping concentration of the conduction region 201. In some embodiments, the peak doping concentration of the restriction region 180 is higher than the second peak doping concentration of the conduction region 201. For example, when the photodetector device is configured to collect electrons, the restriction region 180 is p-type and the first doped regions 302 a, 302 b are n-type. After photocarriers are generated from the absorber region 10, holes are removed through the second doped region 108 and the second electrode 60, and electrons are confined by the confinement region 180 and migrate from the absorber region 10 toward one of the first doped regions 302 a, 302 b through the passage 181 instead of migrating out across the heterointerface between the absorber region 10 and the substrate 20. Thus, the photodetector device 600 c may have improved demodulation contrast by including the confinement region 180 between the absorber region 10 and the first doped regions 302 a, 302 b.

[0119] FIG. 6F shows a top view of a photodetector device according to an embodiment. The photodetector device 600f in FIG. 6F is similar to the photodetector device 600c in FIG. 6C. The difference is that the confinement region 180 extends to cover the two other side surfaces 13 of the absorber region 10 to further confine carriers to pass through a passage 181 at one of the side surfaces 13 of the absorber region 10 instead of moving out the other side surfaces 13 of the absorber region 10. In an embodiment, the peak doping concentration of the confinement region 180 is lower than the peak doping concentration of the second doped region 108. In an embodiment, the confinement region 180 and the second doped region 108 are formed by two different fabrication process steps, such as using different masks.

[0120] FIG. 6G shows a top view of a photodetector device according to an embodiment. The photodetector device 600g in FIG. 6G is similar to the photodetector device 600f in FIG. 6F. The difference is that the second doped region 108 can function as the confinement region 180 described in FIG. 6F. In other words, the second doped region 108 can both remove carriers not collected by the first doped regions 302a, 302b and confine carriers collected from the absorber region 10 to one of the first doped regions 302a, 302b through the passage 181 at one of the side surfaces 13 of the absorber region 10, instead of moving out the other side surface 13 of the absorber region 10.

[0121] FIG. 7A shows a top view of a photodetector device according to an embodiment. FIG. 7B shows a cross-sectional view along line A-A' in FIG. 7A according to an embodiment. Photodetector device 700a is similar to photodetector device 300a in FIG. 3A. Differences are described below. In an embodiment, the photodetector device includes N switches electrically coupled to absorber region 10 and partially formed in substrate 20, where N is an integer greater than 3. For example, N can be 3, 4, 5, etc. In an embodiment, a pixel of the photodetector further includes Y control signals different from each other, where 3≦Y≦N and Y is a positive integer, each of the control signals controlling one or more of the control regions of photodetector device 700a. In an embodiment, each of the control signals includes a phase, and the phase of one of the control signals does not overlap with the phase of another of the control signals. Referring to FIGS. 7A and 7B, in an embodiment, photodetector device 700a includes four switches (not numbered) electrically coupled to absorber region 10 and partially formed in substrate 20. Each of the switches includes a control region C1, C2, C3, C4 that includes a control electrode 340a, 340b, 340c, 340d. Each of the switches includes a readout electrode 330a, 330b, 330c, 330d that is separated from the control electrode 340a, 340b, 340c, 340d. In one embodiment, the readout electrodes 330a, 330b, 330c, 330d and the control electrodes 340a, 340b, 340c, 340d are formed on the first surface 21 of the substrate 20 and are separated from the absorber region 10.

[0122] In one embodiment, four switches are located on each of the four sides 13 .

[0123] In one embodiment, each of the switches includes a first doped region (not shown) beneath the readout electrode 330a, 330b, 330c, 330d, which is similar to the first doped regions 302a, 302b as described in FIG. 3A.

[0124] In one embodiment, a pixel of a photodetector device includes four control signals for controlling control regions C1, C2, C3, and C4, respectively, to control the direction of movement of electrons or holes generated by the absorber region 10. For example, when a voltage is used, if the control signal controlling control region C1 is biased relative to the other control signals, an electric field is created between the four portions immediately below the control electrodes 340a, 340b, 340c, and 340d as in the absorber region 10, and free carriers in the absorber region 10 drift toward one of the first doped regions below the readout electrodes 330a, 330b, 330c, and 330d depending on the direction of the electric field. In one embodiment, each of the control signals has a phase that is not overlapped by the phase of each other.

[0125] In an embodiment, the conductive region 201 can be any suitable shape, such as rectangular or square.

[0126] 7C shows a top view of a photodetector device according to an embodiment. The photodetector device 700c is similar to the photodetector device 700a in FIG. 7A. The differences are as follows: the arrangement of the readout electrodes 330a, 330b, 330c, and 330d and the arrangement of the control electrodes 340a, 340b, 340c, and 340d are different. For example, four switches are arranged at the four corners of the absorption region 10, respectively.

[0127] FIG. 7D shows a top view of a photodetector device according to one embodiment. Photodetector device 700d is similar to photodetector device 700a in FIG. 7A. Differences are described below. Photodetector device 700d includes eight switches (not labeled) electrically coupled to absorber region 10 and partially formed in substrate 20. Similarly, each of the switches includes a control region (not labeled) including control electrodes 340a, 340b, 340c, 340d, 340e, 340f, 340g, and 340h, and includes readout electrodes 330a, 330b, 330c, 330d, 330e, 330f, 330g, and 330h separated from control electrodes 340a, 340b, 340c, 340d, 340e, 340f, 340g, and 340h.

[0128] In one embodiment, the photodetector device includes a pixel including the photodetector device 700d described above, and the pixel includes multiple control signals that are different from each other and control multiple switches of the photodetector device 700d. That is, in the same pixel, the number of control signals is less than the number of switches. For example, the pixel can include two control signals that are different from each other, each controlling two of the switches. For example, the control electrode 340a and the control electrode 340b can be electrically coupled to and controlled by the same control signal. In one embodiment, the pixel can include multiple control signals that control each switch. That is, in the same pixel, the number of control signals is equal to the number of switches. For example, a pixel of the photodetector device includes eight control signals that are different from each other and control each switch of the photodetector device 700d.

[0129] FIG. 7E shows a top view of a photodetector device according to one embodiment. The photodetector device 700e is similar to the photodetector device 700d in FIG. 7D. The differences are described below. The arrangement of the readout electrodes 330a, 330b, 330c, 330d, 330e, 330f, 330g, and 330h is different from the arrangement of the control electrodes 340a, 340b, 340c, 340d, 340e, 340f, 340g, and 340h. For example, every other switch among the eight switches is located at each of the four corners of the absorption region 10. The conduction region 201 may be, but is not limited to, an octagon.

[0130] FIG. 8A shows a top view of a photodetector device according to an embodiment. FIG. 8B shows a cross-sectional view along line A-A' in FIG. 8A according to an embodiment. The photodetector device 800a in FIG. 8A is similar to the photodetector device 700a in FIG. 7A. Differences are described below. The second doped region 108 is in the substrate 20. In other words, the fourth peak doping concentration of the second doped region 108 is located in the substrate 20. In an embodiment, the second doped region 108 includes multiple subregions 108a, 108b, 108c, and 108d that are separated from each other and directly contact the absorber region 10. For example, the subregions 108a, 108b, 108c, and 108d may contact or overlap at least a portion of the side surface 13 of the absorber region 10. As a result, carriers generated from absorber region 10 that are not collected by the first doped regions can travel from absorber region 10 toward one or more of sub-regions 108a, 108b, 108c, 108d through the heterointerface between absorber region 10 and substrate 20. In some embodiments, no sub-regions 108a, 108b, 108c, 108d are between absorber region 10 and the first doped region of any switch to avoid impeding the path of collected carriers traveling from absorber region 10 toward one of the first doped regions. For example, in one embodiment, the sub-regions 108a, 108b, 108c, and 108d are positioned at the four corners of the absorption region 10, respectively, and the four switches are positioned at the four side surfaces 13, respectively, so that the path of holes moving from the absorption region 10 toward one or more of the sub-regions 108a, 108b, 108c, and 108d is different from the path of electrons moving from the absorption region 10 toward one of the first doped regions.

[0131] In one embodiment, the second electrode 60 comprises sub-electrodes 60a, 60b, 60c, and 60d electrically coupled to the sub-regions 108a, 108b, 108c, and 108d, respectively. The sub-electrodes 60a, 60b, 60c, and 60d are disposed on the first surface 21 of the substrate 20.

[0132] By having the second doped region 108 in the substrate 20 instead of the absorber region 10, the sub-electrodes 60a, 60b, 60c, 60d, the readout electrodes 330a, 330b, 330c, 330d, and the control electrodes 340a, 340b, 340c, 340d can all be flush above the first surface 21 of the substrate 20. Therefore, the height difference between any two of the sub-electrodes 60a, 60b, 60c, 60d, the readout electrodes 330a, 330b, 330c, 330d, and the control electrodes 340a, 340b, 340c, 340d can be reduced, thereby allowing subsequent fabrication processes to benefit from this design. Another advantage is that the area of ​​the absorber region 10 that absorbs optical signals can be increased.

[0133] FIG. 8C shows a top view of a photodetector device according to one embodiment. The photodetector device 800c in FIG. 8C is similar to the photodetector device 800a in FIG. 8A. The differences are described below. The arrangement of the readout electrodes 330a, 330b, 330c, and 330d and the arrangement of the control electrodes 340a, 340b, 340c, and 340d are different; the arrangement of the sub-electrodes 60a, 60b, 60c, and 60d is different; and the arrangement of the sub-regions 108a, 108b, 108c, and 108d is different. For example, four switches are respectively arranged at the four corners of the absorber region 10, and the sub-regions 108a, 108b, 108c, and 108d and the sub-electrodes 60a, 60b, 60c, and 60d are arranged on each side 13 of the absorber region 10.

[0134] 8D shows a top view of a photodetector device according to an embodiment. Photodetector device 800d is similar to photodetector device 800a in FIG. 8A. Differences are described below. Photodetector device 800d includes eight switches (not labeled) electrically coupled to absorber region 10 and partially formed in substrate 20, similar to photodetector device 700d in FIG. 7D. The pixels of the photodetector also include a plurality of control signals as described in FIG. 7D.

[0135] 8E shows a top view of a photo-sensing device according to one embodiment. The photo-sensing device 800e is similar to the photo-sensing device 800d in FIG. 8D. The differences are described below: the arrangement of the readout electrodes 330a, 330b, 330c, 330d, 330e, 330f, 330g, and 330h and the arrangement of the control electrodes 340a, 340b, 340c, 340d, 340e, 340f, 340g, and 340h are different; the arrangement of the sub-electrodes 60a, 60b, 60c, and 60d is different; and the arrangement of the sub-regions 108a, 108b, 108c, and 108d is different. For example, every other switch of the eight switches is located at each of the four corners of the absorbent region 10, and sub-regions 108a, 108b, 108c, 108d and sub-electrodes 60a, 60b, 60c, 60d are located on each side 13 of the absorbent region 10.

[0136] FIG. 9A shows a schematic diagram of a photodetector device according to one embodiment. The photodetector device 900a includes a pixel (not labeled) and a column bus electrically coupled to the pixel. The pixel includes a photodetector device and multiple readout circuits (not labeled) electrically coupled to the photodetector device and the column bus. The photodetector device can be any of the photodetector devices described in FIGS. 3A-3B, 4A-4C, 5A-5C, 6A-6G, 7A-7E, and 8A-8E. For example, the photodetector device 300a in FIG. 3B is shown in FIG. 9A. Each of the readout circuits is similar to the readout circuit described in FIG. 2E. Differences are described below. Each of the readout circuits is electrically coupled to a respective first doped region of a switch of the photodetector device to process carriers of a first type. For example, if the first doped regions are n-type, the readout circuit processes electrons collected from the respective first doped regions for further use.

[0137] The number of readout circuits is the same as the number of switches. That is, the photodetector device includes N switches electrically coupled to the absorption region 10 and partially formed in the substrate 20, and the pixel of the photodetector device further includes Z readout circuits electrically coupled to the photodetector device, where Z=N. For example, the number of switches in the photodetector devices in FIGS. 3A-3B, 4A-4C, 5A-5C, and 6A-6G is four, and the number of readout circuits is two. For another example, the number of switches in the photodetector devices in FIGS. 7A-7C and 8A-8C is two, and the number of readout circuits is four. For another example, the number of switches in the photodetector devices in FIGS. 7D-7E and 8D-8E is eight, and the number of readout circuits is eight.

[0138] 9B shows a schematic diagram of a photodetector according to an embodiment. The photodetector 900b is similar to the photodetector 900a in FIG. 9A. The differences are described below. Similar to the readout circuit as shown in FIG. 2F, the readout circuit of the photodetector 900b further includes a voltage-controlled transistor 130A between the first / second switch of the photodetector device 300a and the capacitor 150A.

[0139] FIG. 10A shows a cross-sectional view of a photodetector device according to an embodiment. The photodetector device includes an absorber region 10 and a substrate 20 supporting the absorber region 10. The absorber region 10 is similar to the absorber region 10 described in FIG. 1A. The substrate 20 is similar to the substrate 20 described in FIG. 1A. Differences between the photodetector device 1000a in FIG. 10A and the photodetector device 100a in FIG. 1A are described below. In an embodiment, the photodetector device 1000a further includes a first contact region 204 on the substrate 20, separated from the absorber region 10. The photodetector device 1000a further includes a second contact region 103 on the absorber region 10.

[0140] In some embodiments, the second contact region 103 is of a conductivity type. The first contact region 204 is of a conductivity type different from the conductivity type of the second contact region 103. In some embodiments, the second contact region 103 includes a dopant having a peak doping concentration higher than the first peak doping concentration of the absorber region 10, for example, 1×10 18 cm -3 From 5 x 10 20 cm -3 In some embodiments, the first contact region 204 includes a dopant having a peak doping concentration that is higher than the second peak doping concentration of the second dopant in the substrate 20, for example, 1×10 18 cm -3 From 5 x 10 20 cm -3 In an embodiment, the second contact region 103 is not disposed on the first contact region 204 along a direction D1 that is substantially perpendicular to the first surface 21 of the substrate 20.

[0141] The photodetector device comprises a first electrode 140 coupled to the first contact region 204 and a second electrode 160 coupled to the second contact region 103. The second electrode 160 is on a first surface 11 of the absorber region 10. The first electrode 140 is on a first surface 21 of the substrate 20. In one embodiment, the substrate 20 of the photodetector device 1000a comprises a conductive region 201 similar to the conductive region 201 described in FIG. 1A.

[0142] In some embodiments, the photodetector device 1000a further comprises a third contact region 208 in the substrate 20. In some embodiments, the third contact region 208 is between the second contact region 103 and the first contact region 204. The third contact region 208 is of the same conductivity type as the conductivity type of the second contact region 103. The third contact region 208 comprises a conductivity type different from the conductivity type of the first contact region 204. In some embodiments, the third contact region 208 comprises a dopant having a peak doping concentration higher than the second peak doping concentration of the conduction region 201, for example, 1×10 18 cm -3 and 5×10 20cm -3 It can be between.

[0143] In some embodiments, the distance between the first surface 21 of the substrate 20 and the location of the first contact region 204 having the peak dopant concentration is less than 30 nm. In some embodiments, the distance between the first surface 21 of the substrate 20 and the location of the third contact region 208 having the peak dopant concentration is less than 30 nm.

[0144] In some embodiments, the third contact region 208 may entirely overlap the conductive region 201. The third contact region 208 and the first contact region 204 are both below the first surface 21 of the substrate 20.

[0145] In an embodiment, the light-detecting device further comprises a third electrode 130 electrically coupled to the third contact region 208. The third electrode 130 and the first electrode 140 are formed coplanar on the first surface 21 of the substrate 20, and thus the height difference between the third electrode 130 and the first electrode 140 can be reduced, which is beneficial for subsequent fabrication processes.

[0146] The photodetector device 1000a may be a lock-in pixel or an avalanche phototransistor, depending on the circuitry electrically coupled to the photodetector device 1000a and / or the manner in which the photodetector device 1000a operates.

[0147] For example, when the light detection device 1000a serves as a lock-in pixel, the third contact region 208 and the first contact region 204 can be considered as a switch. A readout circuit is electrically coupled to the first contact region 204 through the first electrode 140, a control signal, which is a modulated signal, is electrically coupled to the third contact region 208 through the third electrode 130 to control the on / off state of the switch, and a voltage or ground may be applied to the second contact region 103 to remove carriers not collected by the first contact region 204. The lock-in pixel may be included in an indirect TOF system.

[0148] In one embodiment, when the photodetector device 1000a functions as an avalanche phototransistor, the portion of the substrate 20 or the portion of the conduction region 201 through which carriers pass between the third contact region 208 and the first contact region 204 serves as a multiplication region M during operation of the photodetector device 1000a. In the multiplication region, photocarriers generate additional electrons and holes through impact ionization, which initiates a chain reaction of avalanche multiplication. As a result, the photodetector device 100a has gain. In one embodiment, the substrate 20 can support the absorption region 10 and simultaneously amplify carriers through avalanche multiplication. In one embodiment, the third contact region 208 can be a charge region. The avalanche phototransistor can be directly included in a TOF system.

[0149] A method for operating the photodetector device 1000a capable of collecting electrons in FIG. 10A includes applying a first voltage to the first electrode 140, a second voltage to the second electrode 160, and a third voltage to the third electrode 130 to generate a first total current and form a reverse-biased p-n junction between the first electrode 140 and the third electrode 130, and receiving incident light at the absorption region 10 to generate a second total current greater than the first total current.

[0150] In some embodiments, the first voltage is greater than the second voltage, and in some embodiments, the third voltage is between the first and second voltages.

[0151] In one embodiment, the first total current comprises a first current and a second current. The first current flows from the first electrode 140 to the third electrode 130. The second current flows from the first electrode 140 to the second electrode 160.

[0152] In some embodiments, the second total current includes a third current, which flows from the first electrode 140 to the second electrode 160.

[0153] In one embodiment, the second total current comprises a third current and a fourth current. The fourth current flows from the first electrode 140 to the third electrode 130.

[0154] In some embodiments, the second voltage applied to the first electrode is, for example, 0 volts.

[0155] In some embodiments, the third voltage may be selected to sweep photocarriers from the absorption region 10 to the multiplication region, i.e., to a portion of the substrate 20, or to a portion of the conduction region 201 between the third contact region 208 and the first contact region 204. In some embodiments, the voltage difference between the second voltage and the third voltage is less than the voltage difference between the first voltage and the third voltage to facilitate the movement of photocarriers from the absorption region 10 to the multiplication region in the substrate 20 so as to multiply the photocarriers. For example, when the second voltage applied to the second electrode 160 is 0 volts, the third voltage applied to the third electrode 130 may be 1 V, and the first voltage applied to the first electrode 140 may be 7 V.

[0156] In one embodiment, the voltage difference between the first voltage and the third voltage is less than the avalanche breakdown voltage of the photodetector device 1000a, at which the photodetector device 1000a initiates an avalanche multiplication chain reaction to operate the multiplication region in a linear mode.

[0157] In one embodiment, the voltage difference between the first voltage and the third voltage is greater than the avalanche breakdown voltage of the photodetector device 1000a, at which the photodetector device 1000a initiates an avalanche multiplication chain reaction to operate the multiplication region in Geiger mode.

[0158] In an embodiment, the carriers collected by the first contact region 204 may be further processed by circuitry electrically coupled to the photodetector device 1000a.

[0159] In an embodiment, carriers not collected by the first contact region 204 can move towards the second contact region 103 and can be further removed by a circuit electrically coupled to the photodetector device 1000a.

[0160] Similarly, by designing the concentration and materials of the carrier conducting layer, which is the absorber region 10 and, in some embodiments, the substrate 20, the photodetector device 1000a may have a lower dark current.

[0161] FIG. 10B shows a top view of a photodetector device according to an embodiment. FIG. 10C shows a cross-sectional view along line A-A' in FIG. 10B according to an embodiment. The photodetector device 1000b in FIG. 10B is similar to the photodetector device 1000a in FIG. 10A. The differences are described below. Preferably, the photodetector device 1000b serves as an avalanche phototransistor. The photodetector device 1000b further includes a correction element 203 integrated with the substrate 20. The correction element 203 is for correcting the position where multiplication occurs in the substrate 20. In an embodiment, the resistance of the correction element 203 is higher than the resistance of the substrate 20 so as to correct the position where multiplication occurs in the substrate 20. Therefore, more carriers can pass through the location where the strongest electric field is located, increasing the avalanche multiplication gain.

[0162] For example, the modifying element 203 is a trench formed in the first surface 21 of the substrate 20. The trench can block carriers from passing through a defined area of ​​the substrate 20, thereby reducing the area in the substrate 20 through which the carriers pass. The trench has a depth, and the ratio of the depth to the thickness of the substrate 20 can be between 10% and 90%. The first contact region 204 is exposed in the trench so as to be electrically coupled to the first electrode 140. In some embodiments, the width of the trench can be greater than, substantially equal to, or smaller than the width of the first contact region 204. In some embodiments, the width of the trench can be greater than the width of the first contact region 204 so as to allow carriers to pass through a high electric field region next to the first contact region 204.

[0163] The corrective element 203 causes carriers, eg electrons, to pass through the multiplication region where the strongest electric field is located, such as the region next to the first contact region 204, thereby increasing the avalanche multiplication gain.

[0164] In one embodiment, the first electrode 140 is formed in a trench. A height difference is between the third electrode 130 and the first electrode 140.

[0165] In some embodiments, the conductive region 201 may be separated from the third contact region 208, may overlap a portion of the third contact region 208, may overlap the entire third contact region 208, may abut the corner of the trench, or may partially overlap the first contact region 204.

[0166] In some embodiments, an insulating material may be filled into the trench.

[0167] FIG. 10D shows a top view of a photodetector device according to an embodiment. FIG. 10E shows a cross-sectional view along line A-A' in FIG. 10D according to an embodiment. FIG. 10F shows a cross-sectional view along line B-B' in FIG. 10D according to an embodiment. The photodetector device 1000d in FIG. 10D is similar to the photodetector device 1000b in FIG. 10B. Differences are described below. In an embodiment, the distance between the first surface 21 of the substrate 20 and the location of the third contact region 208 having the peak dopant concentration is greater than 30 nm. In an embodiment, the photodetector device 1000d further includes a recess 205 formed in the first surface 21 of the substrate 20, exposing the third contact region 208. A third electrode 130 is formed in the recess 205 to be electrically coupled to the third contact region 208. Because the distance between the first surface 21 of the substrate 20 and the location of the third contact region 208, which has the peak dopant concentration, is greater than 30 nm, the distance between the third contact region 208 and the first contact region 204 is shorter, which further restricts the carrier migration path, forcing more carriers to pass through the location of the strongest electric field. Therefore, the avalanche multiplication gain is further improved. In some embodiments, an insulating material can be filled into the recess 205. The first electrode can comprise an interconnect or plug.

[0168] FIG. 10G shows a cross-sectional view of a photodetector device according to an embodiment. The photodetector device 1000g in FIG. 10G is similar to the photodetector device 1000d in FIG. 10D. Differences are described below. In one embodiment, the photodetector device 1000g includes a plurality of third contact regions 208 and a plurality of first contact regions 204. The third contact regions 208 and the plurality of first contact regions 204 are staggered. This design allows multiple multiplication regions to be formed between the plurality of third contact regions 208 and the plurality of first contact regions 204, providing a more uniform electric field profile compared to the photodetector device 1000d. Furthermore, carriers primarily drift along a direction D1 substantially perpendicular to the first surface 21 of the substrate 20, which increases the speed of the photodetector device 1000g because the distance traveled in the vertical direction is typically shorter.

[0169] In an embodiment, the second contact regions 103 are disposed on the first contact regions 204 along a direction D1 that is substantially perpendicular to the first surface 21 of the substrate 20. In an embodiment, the maximum distance d2 between the two outermost third contact regions 208 is greater than the width w3 of the conduction region 201, which causes carriers generated from the absorption region 10 to pass through the multiple multiplication regions between the multiple third contact regions 208 and the multiple first contact regions 204 instead of traveling to other undesired regions in the substrate 20.

[0170] In some embodiments, the plurality of third contact regions 208 may be separated from one another. In some embodiments, the plurality of first contact regions 204 may be separated from one another. In some embodiments, the plurality of third contact regions 208 may be a contiguous region. In some embodiments, the plurality of first contact regions 204 may be a contiguous region.

[0171] In some embodiments, the first contact areas 204 may be in an interlocking arrangement with one another when viewed from above in a first plane (not shown), and in some embodiments, the third contact areas 208 may be in an interlocking arrangement with one another when viewed from above in a second plane (not shown) that is different from the first plane.

[0172] In an embodiment, one or more third electrodes 130 may be electrically coupled to the third contact region 208 through any suitable structure, such as a via, from another cross-sectional view of the photo-detector device 1000g taken from another plane. In an embodiment, one or more first electrodes 140 may be electrically coupled to the first contact region 204 through any suitable structure, such as a via, from another cross-sectional view of the photo-detector device 1000g taken from another plane.

[0173] Figure 10H shows a cross-sectional view of a light-sensing device according to an embodiment. The light-sensing device 1000h in Figure 10H is similar to the light-sensing device 1000a in Figure 10A. The differences are described below.

[0174] The photodetector device 1000h further comprises an intermediate doped region 210 in the substrate 20, which may partially overlap the conductive region 201. The intermediate doped region 210 is of the same conductivity type as the third contact region 208. The intermediate doped region 210 includes a dopant having a peak doping concentration lower than the peak doping concentration of the third contact region 208, for example, 1×10 16 cm -3 and 1×10 18 cm -3 It can be between.

[0175] The photodetector device 1000h further comprises an underdoped region 212 in the substrate 20. The underdoped region 212 is of the same conductivity type as the conductivity type of the first contact region 204. The underdoped region 212 includes a dopant having a peak doping concentration lower than the peak doping concentration of the first contact region 204, e.g., 1×10 18 cm -3 and 1×10 20 cm -3 It can be between.

[0176] The intermediate doped region 210 is between the lower doped region 212 and the second contact region 103 along a direction substantially perpendicular to the first surface 21 of the substrate 20. In some embodiments, the peak doping concentration of the lower doped region 212 is deeper than the peak doping concentration of the intermediate doped region 210.

[0177] In one embodiment, the depth of the third contact region 208 is less than the depth of the first contact region 204. The depth is measured from the first surface 21 of the substrate 20 along a direction substantially perpendicular to the first surface 21 of the substrate 20. The depth is measured when the dopant profile of the dopant is less than 1×10 15 cm -3 until a certain concentration is reached, such as

[0178] A multiplication region M may be formed between the lower doped region 212 and the intermediate doped region 210 during operation of the photodetector device 1000h. The multiplication region M is configured to receive one or more charge carriers from the intermediate doped region 210 and generate one or more additional charge carriers. The multiplication region M is perpendicular to the first surface 21 and has a thickness sufficient to generate one or more additional charge carriers from the one or more carriers generated in the absorption region 10. The thickness of the multiplication region M may range, for example, between 100 and 500 nanometers (nm). The thickness may determine the voltage drop across the multiplication region M to reach avalanche breakdown. For example, a thickness of 100 nm corresponds to a voltage drop of approximately 5 to 6 volts required to reach avalanche breakdown in the multiplication region M. In another example, a thickness of 300 nm corresponds to a voltage drop of approximately 13 to 14 volts required to reach avalanche breakdown in the multiplication region M.

[0179] In an embodiment, the shape of the third contact area 208, the shape of the first contact area 204, the shape of the third electrode 130, and the shape of the first electrode 140 may be, but is not limited to, a ring.

[0180] 10C, the multiplication region M in the photodetector device 1000h can be formed in the bulk region of the substrate 20, which avoids defects that may exist on the trench surface described in FIG. 10C. As a result, the dark current is further reduced. Furthermore, the height difference between the third electrode 130 and the first electrode 140 can be reduced, thereby allowing subsequent fabrication processes to benefit from this design.

[0181] FIG. 10I shows a cross-sectional view of a photodetector device according to one embodiment. The photodetector device 1000i in FIG. 10I is similar to the photodetector device 1000h in FIG. 10H. The differences are described below. The substrate 20 comprises a base portion 20a, an upper portion 20b, and a middle portion 20c. The middle portion 20c is located between the base portion 20a and the upper portion 20b. The absorber region 10, the second contact region 103, and the conductive region 201 are located in the upper portion 20b. The third contact region 208 is located in the middle portion 20c. The first contact region 204 is located in the base portion 20a. The upper portion 20b has a width smaller than that of the middle portion 20c, and the third contact region 208 is exposed to be electrically coupled to the third electrode 130. The intermediate portion 20 c has a width that is less than the width of the base portion 20 a , and the first contact area 204 is exposed for electrical coupling to the first electrode 140 .

[0182] The intermediate doped region 210 is in the intermediate portion 20c. The under-doped region 212 is in the base portion 20a. Compared with the photodetector device 1000b in FIG. 10C, the multiplication region M in the photodetector device 1000h can be formed in the bulk region of the intermediate portion 20c, which avoids defects that may exist on the trench surface as described in FIG. 10C. As a result, the dark current is further reduced.

[0183] Figure 11A shows a cross-sectional view of a light-sensing device according to an embodiment. The light-sensing device 1100a in Figure 11A is similar to the light-sensing device 1000a in Figure 10A. The differences are described below.

[0184] The second contact region 103 is on the substrate 20. In other words, the peak doping concentration of the second contact region 103 is located in the substrate 20. In some embodiments, the second contact region 103 is below the first surface 21 of the substrate 20 and is in direct contact with the absorber region 10; for example, the second contact region 103 may contact or overlap one of the side surfaces 13 of the absorber region 10 opposite the third contact region 208 and / or the first contact region 204. As a result, carriers generated from the absorber region 10 can travel from the absorber region 10 toward the second contact region 103 through the heterointerface between the absorber region 10 and the substrate 20. The second electrode 160 is on the first surface 21 of the substrate 20.

[0185] By having the second contact region 103 on the substrate 20 instead of the absorbing region 10, the second electrode 160, the first electrode 140, and the third electrode 130 can all be formed flush above the first surface 21 of the substrate 20. Therefore, the height difference between any two of the second electrode 160, the third electrode 130, and the first electrode 140 can be reduced, which allows subsequent fabrication processes to benefit from this design. Another advantage is that the area of ​​the absorbing region 10 that absorbs optical signals can be made larger.

[0186] FIG. 11B shows a top view of a light-sensing device according to an embodiment. FIG. 11C shows a cross-sectional view along line A-A' in FIG. 11B according to an embodiment. The light-sensing device 1100b in FIG. 11B is similar to the light-sensing device 1100a in FIG. 11A. The differences are described below. The light-sensing device 1100b further comprises a correction element 203 integrated with the substrate 20. The correction element 203 is similar to the correction element 203 described in FIGS. 10B and 10C.

[0187] FIG. 11D shows a top view of a photo-detecting device according to an embodiment. FIG. 11E shows a cross-sectional view along line A-A' in FIG. 11D according to an embodiment. The cross-sectional view along line B-B' in FIG. 11D is the same as FIG. 10F. The photo-detecting device 1100d in FIG. 11D is similar to the photo-detecting device 1100b in FIG. 11B. Differences are described below. The third contact region 208 is similar to the third contact region 208 in FIGS. 10D and 10E. Additionally, the photo-detecting device 1100d further includes a recess 205 similar to the recess 205 described in FIGS. 10D and 10F, and a third electrode 130 is formed in the recess 205 to be electrically coupled to the third contact region 208.

[0188] FIG. 12A shows a cross-sectional view of a photodetector device according to an embodiment. The photodetector device 1200a in FIG. 12A is similar to the photodetector device 1000b in FIG. 10C. The differences are described below. From the cross-sectional view of the photodetector device, the photodetector device 1200a includes two third contact regions 208, two first contact regions 204, two third electrodes 130, and two first electrodes 140. The third contact regions 208 are disposed on two opposite sides of the absorber region 10, and the two third electrodes 130 are electrically coupled to the respective third contact regions 208. The first contact regions 204 are disposed on two opposite sides of the absorber region 10, and the first electrodes 140 are electrically coupled to the respective first contact regions 204. The distance between the third contact regions 208 is smaller than the distance between the first contact regions 204. The substrate 20 further includes a waveguide 206 associated with the absorber region 10 to guide and / or confine an incident optical signal passing through a defined region of the substrate 20. For example, the waveguide 206 may be a ridge defined by two trenches 207. The ridge has a width greater than that of the absorber region 10. The incident optical signal can be confined and propagated along the ridge 206. The trenches may be similar to the trenches described in FIGS. 10B and 10C or may be correction elements 203 described in FIGS. 10B and 10C. For example, carriers are passed through the multiplication region where the strongest electric field is located, such as the region near each corner of the trench, thereby increasing the avalanche multiplication gain. Similar to FIGS. 10B and 10C, each of the first contact regions 204 is exposed in the respective trenches 206 for electrical coupling to a respective first electrode 140.

[0189] 12B shows a cross-sectional view of a photodetector device according to an embodiment. The photodetector device 1200b in FIG. 12B is similar to the photodetector device 1100a in FIG. 12A. The differences are described below. The third contact regions 208 are similar to the third contact regions 208 in FIGS. 10D and 10E. For example, the distance between the first surface 21 of the substrate 20 and each location of the third contact regions 208 having a peak dopant concentration is greater than 30 nm.

[0190] 12C shows a cross-sectional view of a photodetector device according to an embodiment. The photodetector device 1200c in FIG. 12C is similar to the photodetector device 1000g in FIG. 10G. The differences are described below. The photodetector device 1200c further includes a waveguide 206 integrated with the substrate 20, and the waveguide 206 is similar to the waveguide 206 described in FIG. 12A.

[0191] FIG. 13A shows a cross-sectional view of a photodetector device according to an embodiment. The photodetector device includes an absorber region 10 and a substrate 20 supporting the absorber region 10. The absorber region 10 is similar to the absorber region 10 described in FIG. 1A. The substrate 20 is similar to the substrate 20 described in FIG. 1A. Differences between the photodetector device 1300a in FIG. 13A and the photodetector device 100a in FIG. 1A are described below.

[0192] The photodetector device 1300a includes a collector region 1302 and an emitter region 1304 separated from the collector region 1302. In one embodiment, the collector region 1302 is in the absorber region 10. The emitter region 1304 is outside the absorber region 10 and is in the substrate 20. The collector region 1302 is for collecting amplified photocarriers generated in the absorber region 10. The collector region 1302 is of a conductivity type. The emitter region 1304 is of the same conductivity type as the collector region 1302. The conductivity type of the absorber region 10 is the same as the conductivity type of the collector region 1302. For example, the conductivity type of the absorber region 10 is p-type, and the conductivity types of the collector region 1302 and the emitter region 1304 are p-type. In some embodiments, the collector region 1302 includes a dopant and has a dopant profile with a peak dopant concentration higher than the first peak doping concentration of the absorber region 10, e.g., 5×10 18 cm -3 From 5 x 10 20 cm -3 The range may be:

[0193] In some embodiments, the emitter region 1304 includes a dopant and has a dopant profile with a peak dopant concentration that is greater than the second peak doping concentration of the second dopant in the substrate 20, e.g., greater than 1×10 17 cm -3 From 5 x 10 18 cm -3 The range may be:

[0194] The photodetector device 1300a includes a first electrode 1330 electrically coupled to the collector region 1302 and a second electrode 1340 electrically coupled to the emitter region 1304. The first electrode 1330 serves as the collector electrode. The second electrode 1340 serves as the emitter electrode.

[0195] 1A , a conduction region (not shown) may be formed in a carrier conduction layer, which in some embodiments is substrate 20. Conduction region 201 is between emitter region 1304 and absorber region 10. In some embodiments, conduction region 201 overlaps absorber region 10 and emitter region 1304 to restrict the path of carriers generated from absorber region 10 traveling toward emitter region 1304. In some embodiments, conduction region 201 has a depth measured from first surface 21 of substrate 20 along a direction substantially perpendicular to first surface 21 of substrate 20. The depth is determined by measuring a dopant profile of the second dopant from 1×10 to 1×10. 15 cm -3 until a certain concentration is reached, such as

[0196] Similarly, by designing the concentration and materials of the carrier conducting layer, which is the absorber region 10 and, in some embodiments, the substrate 20, the photodetector device 1300a may have a lower dark current.

[0197] In one embodiment, a method for operating the photodetector device 1300a includes generating a reverse-biased PN junction between the absorber region 10 and the substrate 20, generating a forward-biased PN junction between the substrate 20 and the emitter region 1304, and receiving incident light at the absorber region 10 to generate an amplified photocurrent.

[0198] For example, photodetector device 1300a may include a p-doped emitter region 1304, an n-doped substrate 20, a p-doped absorber region 10, and a p-doped collector region 1302. A PN junction between the p-doped emitter region 1304 and the n-doped substrate 20 is forward biased such that hole current is emitted into the n-doped substrate 20. A PN junction between the p-doped absorber region 10 and the n-doped substrate 20 is reverse biased such that the emitted hole current is collected by a first electrode 1330. When light (e.g., light at 940 nm, 1310 nm, or any suitable wavelength) is incident on photodetector device 1300a, photocarriers including electrons and holes are generated in the absorber region 10. The photogenerated holes are collected by the first electrode 1330. The photogenerated electrons are directed towards the n-doped substrate 20, which, due to charge neutrality, increases the forward bias. The increased forward bias further increases the hole current collected by the first electrode 1330, resulting in an amplified hole current generated by the photodetector device 1300a.

[0199] Therefore, the second electrical signal collected by the collector region 1302 is greater than the first electrical signal generated by the absorption region 10, thereby providing the photodetector device 1300a with gain and thus an improved signal-to-noise ratio.

[0200] In one embodiment, a method for operating a photodetector device 1300a capable of collecting holes includes the steps of applying a first voltage V1 to the first electrode 1330 and applying a second voltage V2 to the second electrode 1340 to generate a first current flowing from the second electrode 1340 to the first electrode 1330, where the second voltage V2 is higher than the first voltage V1; and receiving incident light at the absorption region 10 to generate a second current flowing from the second electrode 1340 to the first electrode 1330 after the absorption region 10 generates photocarriers from the incident light, where the second current is higher than the first current.

[0201] In one embodiment, a method for operating a photodetector device 1300a capable of collecting holes includes applying a second voltage V2 to the second electrode 1340 to form a forward bias between the emitter region 1304 and the substrate 20 to form a first hole current, and applying a first voltage V2 to the first electrode 1330 to form a reverse bias between the substrate 20 and the absorber region 10 to collect a portion of the first hole current, where the second voltage V2 is higher than the first voltage V1; receiving incident light at the absorber region 10 to generate photocarriers including electrons and holes; amplifying a portion of the photocarriers' holes to generate a second hole current; and collecting a portion of the second hole current by the collector region 1302, where the second hole current is greater than the first hole current.

[0202] FIG. 13B shows a cross-sectional view of a photodetector device according to an embodiment. Photodetector device 1300b in FIG. 13B is similar to photodetector device 1300a in FIG. 13A. Differences are described below. The photodetector device further includes a base region 1308 and a third electrode 1360 electrically coupled to the base region 1308. The third electrode 1360 serves as a base electrode. In an embodiment, the base region 1308 is between the collector region 1302 and the emitter region 1304. The base region 1308 is of a different conductivity type than the conductivity type of the collector region 1302. In an embodiment, the base region 1308 is in the substrate 20.

[0203] In some embodiments, the foundation region 1308 includes a dopant and has a dopant profile with a peak dopant concentration that is greater than the second peak doping concentration of the second dopant in the substrate 20, e.g., greater than 1×10 17 cm -3 From 5 x 10 18 cm -3 The range may be:

[0204] The third electrode 1360 is for biasing the base contact region 1308. In some embodiments, the third electrode 1360 is of the opposite type and is for removing photocarriers that are not collected by the first electrode 1330 during operation of the photodetector device 1300b. For example, if the photodetector device 1300b is configured to collect holes to be further processed by a circuit or the like, the third electrode 1360 is for removing electrons. As such, the photodetector device 1300b may have improved reliability.

[0205] In one embodiment, a method for operating a photodetector device 1300b capable of collecting holes includes applying a second voltage V2 to the second electrode 1340 to form a forward bias between the emitter region 1304 and the substrate 20 to form a first hole current, and applying a first voltage to the first electrode 1330 to form a reverse bias between the substrate 20 and the absorber region 10 to collect a portion of the first hole current, the second voltage V2 being higher than the first voltage V1; applying a third voltage to a third electrode 60 electrically coupled to a base contact region 1308 of the photodetector device; receiving incident light at the absorber region 10 to generate photocarriers including electrons and holes; amplifying a portion of the photocarriers' holes to generate a second hole current; and collecting a portion of the second hole current by the collector region 1302, the third voltage V3 being between the first voltage V1 and the second voltage V2.

[0206] A reverse bias is formed across the p-n junction between the collector region 1302 and the base region 1308, and a forward bias is formed across the p-n junction between the emitter region 1304 and the base region 1308. In one embodiment, the steps of applying the third voltage V3 to the third electrode 1360 and applying the first voltage V1 to the first electrode 1330 and the second voltage V2 to the second electrode 1340 are operated simultaneously.

[0207] In some embodiments, the arrangement of the third electrode 1360, first electrode 1330, and second electrode 1340 may differ from the arrangement of the base region 1308, collector region 1302, and emitter region 1304. For example, in some embodiments, the second electrode 1340 is between the first electrode 1330 and the third electrode 1360. The emitter region 1304 is between the collector region 1302 and the base region 1308.

[0208] FIG. 14A shows a cross-sectional view of a portion of a photodetector device according to an embodiment. The photodetector device can be any of the photodetector devices previously described. The photodetector device further includes a protective layer 1400 on the first surface 11 of the absorber region 10. In an embodiment, the protective layer 1400 also covers a portion of the first surface 21 of the substrate 20, and the readout electrodes 330 a, 330 b and the control electrodes 340 a, 340 b may or may not be on the first surface 1401 of the protective layer 1400. In an embodiment, the absorber region 10 protrudes from the first surface 21 of the substrate 20, and the protective layer 1400 also covers the side surface 13 of the absorber region 10 that is exposed from the substrate 20. That is, the protective layer 1400 can be conformally formed with the absorber region 10 and the substrate 20, as shown in FIG. 14B. In some embodiments, the second electrode 60 is formed on a surface of the protective layer 1400 that is higher than the surface of the protective layer 1400 on which the readout electrodes 330a, 330b and the control electrodes 340a, 340b may be formed. In some embodiments, the control electrodes 340a, 340b, the readout electrodes 330a, 330b, and the second electrode 60 are all disposed on a first surface of the carrier conducting layer. That is, the control electrodes 340a, 340b, the readout electrodes 330a, 330b, and the second electrode 60 are on the same side of the carrier conducting layer, which in some embodiments is the protective layer 1400, which is beneficial for subsequent back-end fabrication processes.

[0209] The protective layer 1400 may be made of amorphous silicon, polysilicon, epitaxial silicon, aluminum oxide (e.g., Al x O y ), silicon oxide (e.g., Si x O y) , Ge oxide (e.g., Ge x O y ), germanium silicon (e.g., GeSi), silicon nitride family (e.g., Si x N y ), high-k materials (e.g., HfO x , ZnO x , LaO x , LaSiO x), and combinations thereof. The presence of the protective layer 1400 can have various effects. For example, the protective layer 1400 can serve as a surface protective layer for the absorber region 10, which can reduce dark current or leakage current caused by defects in the exposed surface of the absorber region 10. In some embodiments, the protective layer 1400 can have a thickness between 20 nm and 100 nm. FIG. 14B shows a cross-sectional view of a photodetector device taken along a line through the second doped region 108 according to some embodiments. In some embodiments, a portion of a doped region in the absorber region 10, such as the second doped region 108 or the second contact region 103, can be formed in a corresponding portion of the protective layer 1400. That is, the dopant of a doped region, such as the second doped region 108 or the second contact region 103, can be in the corresponding portion of the protective layer 1400 between the absorber region 10 and the respective electrode.

[0210] FIG. 14C shows a top view of a photodetector device according to an embodiment. FIG. 14D shows a cross-sectional view along line A-A' in FIG. 14C according to an embodiment. FIG. 14E shows a cross-sectional view along line B-B' in FIG. 14C according to an embodiment. The photodetector device 1400c in FIG. 14C is similar to the photodetector device 300a in FIG. 3A. Differences are described below. The absorber region 10 is completely embedded in the substrate 20. The photodetector device 1400c includes a protective layer 1400 over the absorber region 10 and the substrate 20, which is similar to the protective layer 1400 described in FIG. 14A. In an embodiment, the thickness of the protective layer 1400 can be between 100 nm and 500 nm. The readout electrodes 330a, 330b and the control electrodes 340a, 340b are on a first surface 1401 of the protective layer 1400 and are separated from the absorber region 10. In some embodiments, the readout electrodes 330 a, 330 b, the control electrodes 340 a, 340 b, and the second electrode 60 are formed coplanar in the protective layer 1400, so that the height difference between the electrodes can be reduced. The carrier conducting layer is in the protective layer 1400 instead of the substrate 20. That is, a heterointerface is between the protective layer 1400 and the absorber region 10. In some embodiments, the first surface 11 of the absorber region 10 is at least partially in direct contact with the protective layer 1400, so that a heterointerface is formed between the absorber region 10 and the protective layer 1400. The substrate 20 may be intrinsic and need not be limited to the description in FIG. 1A .

[0211] In one embodiment, the second doped region 108 is similar to the second doped region 108 described in FIG. 3A . The differences are described below. The second doped region 108 is in the protective layer 1400 and the absorber region 10. In one embodiment, the second doped region 108 has a depth equal to or greater than the thickness of the protective layer 1400 to guide carriers with the second type to move toward the second electrode 60 and for further removal by the circuit. The depth is measured from the first surface 1401 of the protective layer 1400 along a direction substantially perpendicular to the first surface 1401 of the protective layer 1400. The depth is measured when the dopant profile of the fourth dopant is 1×1015 cm -3 until a certain concentration is reached, such as

[0212] Similar to photodetector device 100a in FIG. 1A, in one embodiment, the doping concentration of the first dopant at the heterointerface between absorber region 10 and a carrier conducting layer, which in one embodiment is protective layer 1400, is 1×10 16 cm -3 In one embodiment, the doping concentration of the first dopant at the heterointerface is 1×10 16 cm -3 and 1×10 20 cm -3 Between or 1×10 17 cm -3 and 1×10 20 cm -3 In some embodiments, the doping concentration of the second dopant at the heterointerface is less than the doping concentration of the first dopant at the heterointerface. In some embodiments, the doping concentration of the second dopant at the heterointerface is less than 1×10 12 cm -3 and 1×10 17 cm -3 Between.

[0213] In one embodiment, the concentration of the graded doping profile of the first dopant is gradually reduced from the second surface 12 to the first surface 11 of the absorption region 10 to facilitate the movement of carriers such as electrons when the first doped regions 302a, 302b are n-type.

[0214] In some embodiments, the first switch (not labeled) and the second switch (not labeled) are formed partially in a carrier conducting layer, which in some embodiments is the protective layer 1400. In some embodiments, the first doped regions 302a, 302b are in the protective layer 1400. In some embodiments, a third peak doping concentration of the first doped regions 302a, 302b is in the protective layer 1400.

[0215] In one embodiment, the depth of each of the first doped regions 302a, 302b is less than the thickness of the protective layer 1400. The depth is determined by the thickness of the protective layer 1400 from the first surface 1401 of the protective layer 1400 to a depth of 1×10 15 cm -3 The concentration is measured until a certain concentration such as

[0216] In one embodiment, the absorption and carrier control functions, such as carrier demodulation and carrier collection, operate in the absorption region 10 and the carrier conduction layer, which in one embodiment is the protective layer 1400, respectively.

[0217] In some embodiments, the conduction region 201 may be formed in a carrier conduction layer, which in some embodiments is the protective layer 1400. The conduction region 201 may be similar to the conduction region 201 depicted in FIG. 3A , where such conduction region 201 overlaps a portion of the first doped regions 302 a, 302 b in the protective layer 1400. Differences are described below. In some embodiments, the conduction region 201 has a depth equal to or greater than the thickness of the protective layer 1400 to confine and guide carriers with a first type to move toward one of the first doped regions 302 a, 302 b. The depth is measured from the first surface 1401 of the protective layer 1400 along a direction substantially perpendicular to the first surface 1401 of the protective layer 1400. The depth may be greater than or equal to the thickness of the protective layer 1400, where the dopant profile of the second dopant is greater than or equal to 1×10. 15 cm -3 until a certain concentration is reached, such as

[0218] In one embodiment, the width of the absorber region 10 is smaller than the distance between the two control electrodes 340a, 340b, which can reduce leakage current between the two control electrodes 340a, 340b. FIG. 14F shows a cross-sectional view of a photodetector device according to one embodiment. The photodetector device 1400f in FIG. 14F is similar to the photodetector device 1400e in FIG. 14E. The differences are described below. The absorber region 10 is partially embedded in the substrate 20. A protective layer 1400 is conformally formed on the absorber region 10 and the substrate 20 to cover the exposed side surface 13 of the absorber region 10. The conductive region 201 can surround the absorber region 10 or overlap the entire surface of the absorber region 10, i.e., overlap the first surface 11, the second surface 12, and all side surfaces 13 of the absorber region 10.

[0219] In one embodiment, the depth of each of the first doped regions 302a, 302b is greater than the thickness of the protective layer 1400. The depth is determined by the thickness of the protective layer 1400 from the first surface 1401 of the protective layer 1400 such that the dopant profile is 1×10 15 cm -3 In one embodiment, the depth of each of the first doped regions 302a, 302b is less than the thickness of the protective layer 1400. The depth is measured from the first surface 1401 of the protective layer 1400 to a position where the dopant profile reaches a specific concentration, such as 1×10 15 cm -3 The concentration is measured until a certain concentration such as

[0220] FIG. 14G shows a top view of a photodetector device according to an embodiment. FIG. 14H shows a cross-sectional view along line A-A' in FIG. 14G according to an embodiment. FIG. 14I shows a cross-sectional view along line B-B' in FIG. 14G according to an embodiment. The photodetector device 1400g in FIG. 14G is similar to the photodetector device 1400c in FIG. 14C. The differences are described below. The second doped region 108 is in the substrate 20. In other words, the fourth peak doping concentration of the second doped region 108 is located in the substrate 20. In an embodiment, the second doped region 108 is below the first surface 1401 of the protective layer 1400 and is in direct contact with the absorber region 10. For example, the second doped region 108 may contact or overlap one of the side surfaces 13 of the absorber region 10. As a result, carriers generated from the absorber region 10 can travel from the absorber region 10 through the heterointerface between the absorber region 10 and the substrate 20 towards the second doped region 108. The second electrode 60 is on the first surface 1401 of the protective layer 1400.

[0221] FIG. 14J shows a top view of a photodetector device according to an embodiment. FIG. 14K shows a cross-sectional view along line A-A' in FIG. 14J according to an embodiment. FIG. 14L shows a cross-sectional view along line B-B' in FIG. 14J according to an embodiment. The photodetector device 1400j in FIG. 14J is similar to the photodetector device 1400g in FIG. 14G. Differences are described below. In an embodiment, the width of the conduction region 201 is smaller than the distance between the two control electrodes 340a, 340b. The second doped region 108 can surround at least a portion of the absorber region 10. The second doped region 108 can block photogenerated charges in the absorber region 10 from reaching the substrate 20, which increases the collection efficiency of photogenerated carriers in the photodetector device 1400j. The second doped region 108 can also block photogenerated charges in the substrate 20 from reaching the absorption region 10, which increases the velocity of photogenerated carriers in the photodetector device 1400j. The second doped region 108 can include the same material as the absorption region 10, the same material as the substrate 20, a combination of the material of the absorption region 10 and the material of the substrate 20, or a material different from the material of the absorption region 10 and the material of the substrate 20. In some embodiments, the shape of the second doped region 108 can be, but is not limited to, a ring. In some embodiments, the second doped region 108 can reduce crosstalk between two adjacent pixels of the photodetector device. In some embodiments, the second doped region 108 extends to the first surface 21 of the substrate 20.

[0222] 15A shows a gain element 1500a with two terminals. The gain element 1500a includes a lightly doped region 1510 (e.g., an n-type region, e.g., l14 to l17 cm -3 ), an emitter region 1520, and a collector region 1530.

[0223] The collector region 1530 is for collecting carriers and is coupled to a collector electrode (C). The collector region 1530 is heavily p-doped (p++, e.g., 118 to 121 cm -3The emitter region 1520 is for emitting carriers and is coupled to an emitter electrode (E). The emitter region 1520 is of a conductivity type such as heavily p-doped (p++).

[0224] The materials of the lightly doped region 1510, the emitter region 1520, and the collector region 1530 can be silicon, germanium, silicon-germanium, or III-V materials.

[0225] A method for amplifying photocarriers received by the gain element 1500a includes applying a first voltage (e.g., a positive voltage) to the emitter electrode E and a second voltage (e.g., ground) to the collector electrode C, whereby a forward bias is created across the p-n junction between the emitter region 1520 and the lightly doped region 1510, and a reverse bias is created across the p-n junction between the collector region 1530 and the lightly doped region 1530 to collect an electrical signal (e.g., hole current) from the emitter. 1510, receiving carriers of a first type (e.g., electrons from outside the gain element 1500a) in the lightly doped region 1510, increasing the forward bias between the emitter region 1520 and the lightly doped region 1510, and collecting carriers of a second type (e.g., holes) emitted from the emitter region 1520 by the collector region 1530 as an amplified electrical signal (e.g., an amplified hole current).

[0226] As a result, the gain element provides an amplified electrical signal to the collector region based on the received carriers in the lightly doped region, which improves the signal-to-noise ratio.

[0227] FIG. 15B shows that the emitter region 1520 is a moderately doped region 1540 (e.g., an n+ region, e.g., 116 to 119 cm -3 15 shows another implementation of a gain component 1500b surrounded by a .

[0228] FIG. 15C shows that the collector region 1530 is a moderately doped region 1540 (e.g., an n+ region, e.g., 116 to 119 cm -3 15 shows another implementation of a gain component 1500c surrounded by a .

[0229] FIG. 15D shows that the emitter region 1520 and the collector region 1530 are moderately doped regions (e.g., n+ regions, e.g., 116 to 119 cm -3 15 shows another implementation of a gain component 1500d surrounded by a .

[0230] 16A shows a three-terminal gain element 1600a comprising a lightly doped region 1610 (e.g., an n-region), an emitter region 1620, a base region 1640, and a collector region 1630.

[0231] The collector region 1630 is for collecting carriers and is coupled to a collector electrode (C). The collector region 1630 is of a conductivity type, such as heavily p-doped (p++). The base region 1640 is coupled to a base electrode (B) and is of a conductivity type, such as heavily n-doped (n++). The emitter region 1620 is for emitting carriers and is coupled to an emitter electrode (E). The emitter region 1620 is of a conductivity type, such as heavily p-doped (p++).

[0232] The materials of the lightly doped region 1610, the emitter region 1620, the foundation region 1640, and the collector region 1630 can be silicon, germanium, silicon-germanium, or III-V materials.

[0233] A method for amplifying photocarriers received by a gain component includes the steps of establishing a first voltage difference between an emitter electrode E and a base electrode B to form a forward-biased p-n junction, establishing a second voltage difference between a collector electrode C and a base electrode B to form a reverse-biased p-n junction, receiving a first type of carrier (e.g., electrons from outside the gain component 1600a) in a lightly doped region 1610, increasing the first voltage difference to form another forward-biased p-n junction, and collecting a second type of carrier (e.g., holes) emitted from the emitter region 1620 by the collector region 1630 as an amplified electrical signal.

[0234] As a result, gain element 1600a provides an amplified electrical signal to collector region 1630 based on the received carriers in lightly doped region 1610, which improves the signal-to-noise ratio.

[0235] FIG. 16B shows another implementation of a gain element 1600b in which the emitter region 1620 and the foundation region 1640 are surrounded by a moderately doped region 1650 (eg, an n+ region).

[0236] FIG. 16C shows another implementation of a gain element 1600c in which a collector region 1630 and a foundation region 1640 are surrounded by a moderately doped region 1650 (eg, an n+ region).

[0237] FIG. 16D shows another implementation of a gain element 1600d in which the emitter region 1620, the base region 1640, and the collector region 1630 are surrounded by a moderately doped region 1650 (eg, an n+ region).

[0238] 17A shows a CMOS image sensor 1700a (or photodetector) comprising a lightly doped region 1710 (e.g., n-Si), an absorption region 1720 (e.g., p-Ge), and a gain element 1730 (e.g., Si). The gain element 1730 can be a two-terminal or three-terminal gain element as described in FIGS. 15A-15D and 16A-16D.

[0239] The absorbing region 1720 or the lightly doped region 1710 may be made of a semiconductor material of group III-V (e.g., InGaAs, GaAs / AlAs, InP / InGaAs, GaSb / InAs, or InSb), a semiconductor material containing a group IV element (e.g., Ge, Si, or Sn), Si x Ge y Sn 1-x-y (0≦x≦1, 0≦y≦1), Ge 1-a Sn a (0≦a≦0.1), or Ge 1-x Si x (0≦x≦0.1).

[0240] In one embodiment, the bandgap of the lightly doped region 1710 (e.g., n-Si) is larger than the bandgap of the absorber region 1720 (e.g., p-Ge). The gain element 1730 is for collecting photocarriers to generate an amplified electrical signal. The absorber region 1720 includes a first dopant having a first peak doping concentration. The lightly doped region 1710 includes a second dopant having a second peak doping concentration less than the first peak doping concentration to reduce the dark current of the CMOS image sensor 1700a (e.g., less than 10 pA).

[0241] The first peak doping concentration is 1×10 17 cm -3 and 1×10 20 cm -3In one embodiment, the ratio of the first peak doping concentration to the second peak doping concentration is 10 or greater, such that the CMOS image sensor 1700a exhibits low dark current (e.g., 10 pA or less) and high quantum efficiency. The absorber region 1720 can have a graded doping profile, with the first peak doping being far from the interface between the absorber region 1720 and the lightly doped region 1710.

[0242] The absorption region 1720 may comprise a heavily doped region 1722 (e.g., p++) coupled to a voltage (e.g., ground). The lightly doped region 1710 may receive photocarriers of a first type (e.g., electrons), and the heavily doped region 1722 may receive photocarriers of a second type (e.g., holes).

[0243] A method for amplifying optical carriers received by the gain element 1730 includes receiving an optical signal in the absorption region 1720 (e.g., p-Ge) to generate optical carriers having a first type and a second type (e.g., electrons and holes), steering the optical carriers of the first type (e.g., electrons) into the gain region 1730, and generating an amplified electrical signal having the second type (e.g., holes).

[0244] Thereby, the CMOS image sensor 1700a provides an amplified electrical signal based on the optical signal, improving the signal-to-noise ratio.

[0245] In some implementations, the light absorbing region may be covered (as shown by the dotted line) by a different material 1750 (eg, poly-Si).

[0246] FIG. 17B shows an implementation of a CMOS sensor 1700 b in which the light absorbing region 1720 is partially embedded in the lightly doped region 1710 .

[0247] FIG. 17C shows an implementation of a CMOS sensor 1700 c in which the light absorbing region 1720 is completely embedded in the lightly doped region 1710 .

[0248] 17A, FIG. 18A shows a CMOS image sensor 1800a comprising a lightly doped region 1810 (e.g., n-Si), an absorbing region 1820 (e.g., p-Ge), and a gain element 1830 (e.g., Si). Gain element 1830 can be a two-terminal or three-terminal gain element as described in FIGS. 15A-15D and 16A-16D.

[0249] The lightly doped region 1810 may include a heavily doped region 1822 (e.g., p++) coupled to a voltage (e.g., ground). The lightly doped region 1810 can receive both a first type of photocarriers (e.g., electrons) and a second type of photocarriers (e.g., holes). The first type of photocarriers are directed toward the gain element 1830, while the second type of photocarriers are collected by the heavily doped region 1822.

[0250] A method for amplifying optical carriers received by the gain element 1830 includes receiving an optical signal in an absorption region 1820 (e.g., p-Ge) to generate optical carriers having a first type and a second type (e.g., electrons and holes), steering the first type of optical carriers (e.g., electrons) into the gain region 1830, and generating an amplified electrical signal having the second type (e.g., holes).

[0251] Thereby, the CMOS image sensor 1800a provides an amplified electrical signal based on the optical signal, improving the signal-to-noise ratio.

[0252] In some implementations, the light absorbing region 1820 may be covered (as shown by the dotted line) by a different material (eg, poly-Si).

[0253] FIG. 18B shows an implementation of a CMOS sensor 1800 b in which the light absorbing region is partially buried in a lightly doped region 1810 .

[0254] FIG. 18C shows an implementation of a CMOS sensor 1800 c in which the light absorbing region is completely buried in a lightly doped region 1810 .

[0255] FIG. 19A shows a photodetector device 1900a with gain. The photodetector device 1900a includes a lightly doped region 1910 (e.g., n-Si), an absorption region 1920 (e.g., p-Ge), two gain elements 1930a and 1930b, and two control regions 1940a and 1940b (shown as p++, but which may be undoped or lightly doped), each coupled to a control terminal (M1 and M2). The gain elements 1930a and 1930b may be two-terminal or three-terminal gain elements, as described in FIGS. 15A-15D and 16A-16D.

[0256] The absorbing region 1920 or the lightly doped region 1910 may be made of a semiconductor material of group III-V (e.g., InGaAs, GaAs / AlAs, InP / InGaAs, GaSb / InAs, or InSb), a semiconductor material containing a group IV element (e.g., Ge, Si, or Sn), Si x Ge y Sn 1-x-y (0≦x≦1, 0≦y≦1), or Ge 1-a Sn a (0≦a≦0.1).

[0257] In some embodiments, the bandgap of the lightly doped region 1910 (e.g., n-Si) is larger than the bandgap of the absorber region 1920 (e.g., p-Ge). The gain elements 1930a, 1930b are for collecting photocarriers to generate an amplified electrical signal. The absorber region 1920 includes a first dopant having a first peak doping concentration. The lightly doped region 1910 includes a second dopant having a second peak doping concentration less than the first peak doping concentration to reduce the dark current of the photodetector device 1900a (e.g., less than 10 pA).

[0258] The first peak doping concentration and the second peak concentration can be similar to the example described in FIG. 17A.

[0259] The absorption region 1920 may comprise a heavily doped region 1922 (e.g., p++) coupled to a voltage V (e.g., ground). The lightly doped region 1910 may receive photocarriers of a first type (e.g., electrons), and the heavily doped region 1922 may receive photocarriers of a second type (e.g., holes).

[0260] Control signals M1 and M2 can steer optical carriers of a first type toward one of gain components 1930a or 1930b.

[0261] A method for amplifying optical carriers received by a gain element includes receiving an optical signal in an absorption region 1920 (e.g., p-Ge) to generate optical carriers having a first type and a second type (e.g., electrons and holes), steering the first type of optical carriers (e.g., electrons) to a gain region 1930a or 1930b, and generating an amplified electrical signal having the second type (e.g., holes).

[0262] The photodetector device 1900a thereby provides an amplified electrical signal based on the optical signal, improving the signal-to-noise ratio.

[0263] In some implementations, the light absorbing region 1920 may be covered by a different material (eg, poly-Si) (not shown here).

[0264] In some implementations, the light absorbing region 1920 may be partially (e.g., similar to the absorbing region 1720 shown in FIG. 17B) or completely (e.g., similar to the absorbing region 1720 shown in FIG. 17C) embedded in the lightly doped region 1910.

[0265] Figure 19B shows a photodetector device 1900b with gain, which is similar to the photodetector device 1900a in Figure 19A, except that a control region is combined with the emitter region so that an emitter signal (E) can be used to steer and amplify the carrier.

[0266] FIG. 20A shows a top view of an example of a photodetector device 2000 a with gain, such as that described in FIG. 19A or 19B, where the lightly doped region is the substrate 2010 .

[0267] FIG. 20B shows a top view of an example photodetector device 2000b with gain, such as that described in FIG. 19A or 19B , where the substrate 2010 can be intrinsic (e.g., i-Si), lightly p-doped (p-Si), or lightly n-doped (n-Si). A lightly doped region 2012 (e.g., n-Si) can be formed in the substrate 2010 by implantation, diffusion, or other suitable fabrication method. In some implementations, a portion of the absorber region 2020 (e.g., p-Ge) can be formed in a region of the substrate 2010 that is not the lightly doped region 2012. The absorber region 2020 can be coupled to the lightly doped region 2012 through a lightly doped pathway 2030 (e.g., n-Si) formed between the absorber region 2020 and the substrate 2010. Photocarriers (e.g., electrons) generated by the absorption region 2020 can drift from the absorption region 2020 to the lightly doped region 2012, allowing one of the gain components to generate an amplified electrical signal based on a control signal. Thus, the photodetector device 2000b can be formed in an intrinsic, lightly p-doped, or lightly n-doped substrate.

[0268] FIG. 21 shows a photodetector device 2100a with gain. The photodetector device 2100a includes a lightly doped region 2110 (e.g., n-Si) formed in a substrate 2150 (e.g., n-Si, p-Si, or intrinsic Si), an absorption region 2120 (e.g., p-Ge), two gain elements 2130a and 2130b, and two control regions 2140a and 2140b (shown as p++, but which may be undoped or lightly doped) each coupled to a control terminal (M1 and M2). The gain elements 2130a and 2130b may be two-terminal or three-terminal gain elements as described in FIGS. 15A-15D and 16A-16D.

[0269] Thus, the photodetector device 2100a may be formed in a substrate 2150 that is intrinsic, lightly p-doped, or lightly n-doped.

[0270] The absorbing region 2120 or the lightly doped region 2110 may be formed using materials such as those described in Figure 19A.

[0271] In an embodiment, the lightly doped region 2110 may partially or completely overlap the two control regions 2140a and 2140b.

[0272] The absorption region may comprise a heavily doped region 2122 (e.g., p++) coupled to a voltage V (e.g., ground). The lightly doped region 2110 may receive photocarriers of a first type (e.g., electrons) and the heavily doped region 2122 may receive photocarriers of a second type (e.g., holes).

[0273] Control signals M1 and M2 steer optical carriers of a first type toward one of gain components 2130a or 2130b, as described with reference to FIG. 19A.

[0274] In some implementations, the light absorbing region 2120 may be covered by a different material (eg, poly-Si) (not shown here).

[0275] In some implementations, the light absorbing region 2120 may be partially (e.g., similar to the absorbing region 1720 shown in FIG. 17B) or completely (e.g., similar to the absorbing region 1720 shown in FIG. 17C) embedded in the lightly doped region 2110.

[0276] In one implementation, similar to FIG. 19B, control regions 2140a and 2140b may be combined with emitter regions so that an emitter signal (E) can be used to steer and amplify the carrier.

[0277] 22A shows a top view of an example photodetector device 2200a with gain, such as photodetector device 2100a described in FIG. 21 , and FIG. 22B shows a top view of an example photodetector device 2200b with gain, such as photodetector device 2100a described in FIG. 21 , in which a portion of absorber region 2120 (e.g., p-Ge) may be formed in a region of substrate 2150 that is not lightly doped region 2110. Lightly doped region 2110 (e.g., n-Si) may be formed in substrate 2150 by implantation, diffusion, or other suitable fabrication method. Absorber region 2120 may be coupled to lightly doped region 2110 through a lightly doped pathway 2230 (e.g., n-Si) formed between absorber region 2120 and substrate 2150. Photocarriers (e.g., electrons) generated by the absorption region 2120 can drift from the absorption region 2120 to the lightly doped region 2110, allowing one of the gain components to generate an amplified electrical signal (e.g., hole current) based on a control signal.

[0278] 23A shows a top view of an example photodetector device 2300a with gain, in which, similar to FIGS. 18A-18C, a heavily doped region 2322 (e.g., p++) is formed in a lightly doped region 2310 (e.g., n-Si) instead of an absorbing region 2320 (e.g., p-Ge). The lightly doped region 2310 can receive both a first type of photocarriers (e.g., electrons) and a second type of photocarriers (e.g., holes). The first type of photocarriers are directed to gain element 2330a or 2330b based on control signal 2340a or 2340b, while the second type of photocarriers are collected by heavily doped region 2322.

[0279] 23B shows a top view of another example of a photodetector device 2300b with gain that is similar to FIG. 23A , except that a portion of the absorber region 2320 (e.g., p-Ge) may be formed in a region of the substrate 2312 that is not the lightly doped region 2310. The absorber region 2320 may be coupled to the lightly doped region 2310 through a lightly doped path 2350 (e.g., n-Si) formed between the absorber region 2320 and the substrate 2312. Photocarriers (e.g., electrons) generated by the absorber region 2320 can drift from the absorber region 2320 to the lightly doped region 2310, such that one of the gain components 2330a or 2330b can generate an amplified electrical signal (e.g., hole current) based on the control signal 2340a or 2340b.

[0280] 24A shows a top view of an example photodetector device 2400a with gain, similar to FIG. 22A , but with a heavily doped region 2422 (e.g., p++) formed outside of a light absorbing region 2420 (e.g., p-Ge) (similar to that shown in FIGS. 18A-18C ). A portion of the absorbing region 2420 (e.g., p-Ge) may be formed in a region of the substrate 2450 that is not in the lightly doped region 2410. The lightly doped region 2410 may overlap two control regions 2440a and 2440b (e.g., p++) adjacent to the gain elements 2430a and 2430b. Photocarriers (e.g., electrons) generated by the absorption region 2420 can drift from the absorption region 2420 to the lightly doped region 2410, thereby allowing one of the gain components 2430a or 2430b to generate an amplified electrical signal (e.g., hole current) based on a control signal.

[0281] FIG. 24B shows a top view of another example of a photodetector device 2400b with gain, similar to FIG. 22B, but with a heavily doped region 2422 (e.g., p++) formed outside a light-absorbing region 2420 (e.g., p-Ge) (similar to that shown in FIGS. 18A-18C). The absorber region 2420 may be coupled to the lightly doped region 2410 through a lightly doped path 2460 (e.g., n-Si) formed between the absorber region 2420 and the substrate 2450. Photocarriers (e.g., electrons) generated by the absorber region 2420 may drift from the absorber region 2420 to the lightly doped region 2410, allowing one of the gain components 2430a or 2430b to generate an amplified electrical signal (e.g., hole current) based on the control signals 2440a and 2440b.

[0282] 25A-25C show cross-sectional views of a portion of a light-detecting device according to an embodiment. The light-detecting device may have substantially the same structure as any of the previously described embodiments. In an embodiment, unless explicitly stated otherwise in the previous description, with reference to FIG. 25A, the absorber region 10 may be entirely on the first surface 21 of the substrate 20. With reference to FIG. 25B, the absorber region 10 may be partially embedded in the substrate 20, i.e., a portion of each of its sides may be in contact with the substrate 20. With reference to FIG. 25C, the absorber region 10 may be entirely embedded in the substrate 20, i.e., its sides may be in contact with the substrate 20.

[0283] 26A-26D show examples of control regions C1, C2, C3, and C4 of a light-sensing device according to one embodiment. The light-sensing device may have substantially the same structure as any of the previously described embodiments.

[0284] 26A, in some embodiments, the control electrode 340 may be on the first surface 21 of the substrate 20 with the intrinsic region directly below the control electrode 340. The control electrode 340 may result in the formation of a Schottky contact, an ohmic contact, or a combination with intermediate properties between the two, depending on various factors including the material of the substrate 20, or the material of the protective layer, and / or the material of the control electrode 340, and / or the dopant or defect levels of the substrate 20 or protective layer 1400. The control electrode 340 may be any one of control electrodes 340a, 340b, 340c, 340d.

[0285] 26B, in some embodiments, the control region of the switch further comprises a doped region 303 in the substrate 20 below the control electrode 340. In some embodiments, the doped region 303 is of a different conductivity type than the conductivity type of the first doped regions 302a, 302b. In some embodiments, the doped region 303 comprises a dopant and a dopant profile. The peak dopant concentration of the doped region 303 depends on the material of the control electrode 340 and / or the material of the substrate 20 and / or the dopant or defect level of the substrate 20, and may be, for example, 1×10 17 cm-3 From 5 x 10 20 cm -3 The doped region 303 forms a Schottky contact, an ohmic contact, or a combination thereof with the control electrode 340. The doped region is for demodulating carriers generated from the absorption region 10 under the control of a control signal. The control electrode 340 can be any one of the control electrodes 340a, 340b, 340c, and 340d.

[0286] 26C, in one embodiment, the control region of the switch further comprises a dielectric layer 350 between the substrate 20 and the control electrode 340. The dielectric layer 350 prevents direct current conduction from the control electrode 340 to the substrate 20, but allows an electric field to be established in the substrate 20 in response to application of a voltage to the control electrode 340. The electric field established between two of the control regions, for example, between the control regions C1 and C2, can attract or repel charge carriers in the substrate 20. The control electrode 340 can be any one of the control electrodes 340a, 340b, 340c, or 340d.

[0287] 26D, in some embodiments, the control region of the switch further comprises a doped region 303 in the substrate 20 below the control electrode 340, and also comprises a dielectric layer 350 between the substrate 20 and the control electrode 340. The control electrode 340 can be any one of control electrodes 340a, 340b, 340c, 340d.

[0288] In some embodiments, the region of the carrier conduction layer directly beneath the readout electrode can be intrinsic. For example, the region of the substrate directly beneath the readout electrode of each of the switches can be intrinsic. For another example, the region of the protective layer directly beneath the readout electrode of each of the switches can be intrinsic. The readout electrode can form a Schottky contact, an ohmic contact, or a combination with properties intermediate between the two, depending on various factors, including the material of the substrate 20, or the material of the protective layer 1400, or the material of the readout electrode, and / or the dopant or defect levels of the substrate 20 or the protective layer 1400.

[0289] In some embodiments, the dielectric layer 350 may include, but is not limited to, SiO. In some embodiments, the dielectric layer 350 may include, but is not limited to, SiN, SiON, SiN x , SiO x , GeO x , Al2O3, Y2O3, TiO2, HfO2, or ZrO2. In an embodiment, the dielectric layer 350 may include a semiconductor material such as, but not limited to, amorphous Si, polycrystalline Si, crystalline Si, germanium-silicon, or a combination thereof.

[0290] In some embodiments, the conductive region 201 of the photo-detecting device may have any suitable design. For example, taking the conductive region 201 of the photo-detecting device in FIGS. 3A-3B, 4A-4C, 5A-5C, 6A-6G, 7A-7E, 8A-8E, and 14C-14L as an example, the width of the conductive region 201 may be smaller than the distance between the control electrodes 340a and 340b. In some embodiments, the conductive region 201 may not overlap any portion of the two doped regions 303 shown in FIGS. 26B and 26D. In some embodiments, the conductive region 201 may overlap portions of the two doped regions 303 shown in FIGS. 26B and 26D. In some embodiments, the conductive region 201 may overlap the entire doped region 303 shown in FIGS. 26B and 26D. In some embodiments, the conductive region 201 may not overlap any portion of each of the first doped regions 302 a, 302 b. In some embodiments, the conductive region 201 may overlap a portion of each of the first doped regions 302 a, 302 b. In some embodiments, the conductive region 201 may overlap the entire first doped regions 302 a, 302 b.

[0291] 10A and 11A , the conductive region 201 may not overlap any portion of the third contact region 208. In some embodiments, the conductive region 201 may overlap a portion of the third contact region 208. In some embodiments, the conductive region 201 may overlap the entire third contact region 208. In some embodiments, the conductive region 201 may not overlap any portion of the first contact region 204. In some embodiments, the conductive region 201 may overlap a portion of the first contact region 204. In some embodiments, the conductive region 201 may overlap the entire first contact region 204.

[0292] 1A-1D and 2A-2F, the conductive region 201 may not overlap any portion of the first doped region 102. In some embodiments, the conductive region 201 may overlap a portion of the first doped region 102. In some embodiments, the conductive region 201 may overlap the entire first doped region 102.

[0293] In some embodiments, any of the photodetection devices mentioned above, such as those in FIGS. 1A-11E and 13-26D, may include a waveguide similar to waveguide 206 described in FIGS. 12A-12C to guide and / or restrict incident optical signals passing through defined areas of substrate 20. FIG. 27A is a block diagram of an example embodiment of an imaging system. The imaging system may include an imaging module and a software module configured to reconstruct a three-dimensional model of a detected object. The imaging system or imaging module may be implemented in a mobile device (e.g., a smartphone, a tablet, a vehicle, a drone, etc.), ancillary equipment for a mobile device (e.g., a wearable device), a computer system in a vehicle or fixed facility (e.g., a factory), a robotic system, a surveillance system, or any other suitable device and / or system.

[0294] The imaging module includes a transmitting unit, a receiving unit, and a control device. During operation, the transmitting unit can emit an emitted light beam toward a target object. The receiving unit can receive a reflected light beam reflected from the target object. The control device can drive at least the transmitting unit and the receiving unit. In some implementations, the receiving unit and the control device are implemented in one semiconductor chip, such as a system-on-a-chip (SoC). In some cases, the transmitting unit is implemented by two different semiconductor chips, such as a laser emitter chip on a III-V substrate and a Si laser driver chip on a Si substrate.

[0295] The transmitting unit may include one or more light sources, a control circuit for controlling the one or more light sources, and / or an optical structure for manipulating light emitted from the one or more light sources. In certain embodiments, the light source may include light emitted by one or more LEDs or VCSELs that can be absorbed by an absorption region in the light detection device. For example, the one or more LEDs or VCSELs may emit light with a peak wavelength within the visible wavelength range (e.g., a wavelength visible to the human eye), such as 570 nm, 670 nm, or any other applicable wavelength. For other examples, the one or more LEDs or VCSELs may emit light with a peak wavelength above the visible wavelength range, such as 850 nm, 940 nm, 1050 nm, 1064 nm, 1310 nm, 1350 nm, 1550 nm, or any other applicable wavelength.

[0296] In some embodiments, the emitted light beam from the light source may be collimated by one or more optical structures, for example, the optical structures may comprise one or more collimating lenses.

[0297] The receiving unit may include one or more photodetector devices according to any of the embodiments mentioned above. The receiving unit may further include a control circuit for controlling the control circuit and / or an optical structure for steering the light beam reflected from the target object toward the one or more photodetector devices. In one implementation, the optical structure includes one or more lenses that receive the collimated light beam and focus the collimated light beam toward the one or more photodetector devices.

[0298] In one embodiment, the control device includes a timing generator and a processing unit. The timing generator receives a reference clock signal and provides a timing signal to the transmitting unit for modulating the emitted light beam. The timing signal is also provided to the receiving unit for controlling the collection of the optical carriers. The processing unit processes the optical carriers generated and collected by the receiving unit and determines raw data of the target object. The processing unit may include control circuitry, one or more signal processing devices for processing information output from the light detection device, and / or a computer storage medium that may store instructions for determining the raw data of the target object or that may store the raw data of the target object. As an example, the control device in an i-ToF sensor determines the distance between two points using the phase difference between the light beam emitted by the transmitting unit and the light beam received by the receiving unit.

[0299] The software modules may be implemented to perform applications such as facial recognition, gaze tracking, gesture recognition, 3D model scanning / video recording, motion tracking, autonomous vehicles, and / or augmented / virtual reality.

[0300] FIG. 27B shows a block diagram of an example receiving unit or control device, where an image sensor array (e.g., 240×180) can be implemented using any of the implementations of the photodetector devices described with reference to FIGS. 3A-8E and 14C-14L. A phase-locked loop (PLL) circuit (e.g., an integer-N PLL) can generate clock signals (e.g., a four-phase system clock) for modulation and demodulation. These clock signals can be gated and / or conditioned by a timing generator for preset integration times and different operating modes before being sent to the pixel array and external illumination drivers. A programmable delay line can be added to the illumination driver path to delay the clock signals.

[0301] A voltage regulator can be used to control the operating voltage of the image sensor. For example, multiple voltage domains can be used for the image sensor. A temperature sensor can be implemented for possible use in depth calibration and power control.

[0302] The photodetector readout circuitry bridges each of the photodetector devices in the image sensor array to a column analog-to-digital converter (ADC), and the ADC output can be further processed and integrated in the digital domain by a signal processor before reaching the output interface. A memory device can be used to store the output by the signal processor. In one implementation, the output interface can be implemented using a two-lane, 1.2 Gb / s D-PHY MIPI transmitter, or using a CMOS output for lower speed / low cost systems.

[0303] An IC (Internal Circuit) interface may be used to access all of the functional blocks described herein.

[0304] In some embodiments, the photodetector device of the present disclosure further comprises an optical element (not shown) on the pixel. In some embodiments, the photodetector device of the present disclosure further comprises multiple optical elements (not shown) on multiple pixels. The optical element focuses the incoming optical signal for entry into the region of absorption. In some embodiments, the optical element comprises a lens.

[0305] In some embodiments, the p-type dopant comprises a Group III element. In some embodiments, the p-type dopant is boron. In some embodiments, the n-type dopant comprises a Group V element. In some embodiments, the n-type dopant is phosphorus.

[0306] Unless expressly stated otherwise in this disclosure, the absorption region is configured to absorb photons having a peak wavelength in the invisible wavelength range of 800 nm or greater, such as 850 nm, 940 nm, 1050 nm, 1064 nm, 1310 nm, 1350 nm, 1550 nm, or any suitable wavelength range. In certain embodiments, the absorption region receives an optical signal and converts the optical signal into an electrical signal. The absorption region can be any suitable shape, such as, but not limited to, a cylinder, a rectangular prism, etc.

[0307] Unless otherwise explicitly stated in this disclosure, the absorption region has a thickness that depends on the wavelength of photons to be detected and the material of the absorption region. In some embodiments, when the absorption region includes germanium and is designed to absorb photons having wavelengths of 800 nm or greater, the absorption region has a thickness of 0.1 μm or greater. In some embodiments, when the absorption region includes germanium and is designed to absorb photons having wavelengths between 800 nm and 2000 nm, the absorption region has a thickness between 0.1 μm and 2.5 μm. In some embodiments, the absorption region has a thickness between 1 μm and 2.5 μm for greater quantum efficiency. In some embodiments, the absorption region can be grown using blanket epitaxy, selective epitaxy, or other suitable techniques.

[0308] Unless explicitly stated otherwise in this disclosure, the light blocking body has an optical window for defining the position of the absorption region in the absorption region. In other words, the optical window allows an incident optical signal to enter the absorption region and defines the absorption region. In some embodiments, the light blocking body is located on the second surface of the substrate away from the absorption region when the incident light enters the absorption region from the second surface of the substrate. In some embodiments, the shape of the optical window can be elliptical, circular, rectangular, square, diamond, octagonal, or any other suitable shape from the view above the optical window.

[0309] In this disclosure, unless explicitly stated, the type of carriers collected by the first doped region of one of the switches in the same pixel is the same as the type of carriers collected by the first doped region of the other switch. For example, if the photodetector is configured to collect electrons, when the first switch is turned on and the second switch is turned off, the first doped region of the first switch collects electrons of photocarriers generated from the absorption region, and when the second switch is turned on and the first switch is turned off, the first doped region of the second switch also collects electrons of photocarriers generated from the absorption region.

[0310] In this disclosure, unless expressly stated otherwise, the first electrode, second electrode, readout electrode, and control electrode include a metal or alloy, for example, Al, Cu, W, Ti, a Ta-TaN-Cu stack, or a Ti-TiN-W stack.

[0311] In certain embodiments, unless expressly stated otherwise, cross-sectional views shown in this disclosure may be cross-sectional views along any possible cutting line of the light-sensing apparatus or device.

[0312] As used herein, unless otherwise specified, the terms "substantially" and "about" are used to describe and explain small variations. When used in conjunction with an event or circumstance, this term can encompass not only instances in which the event or circumstance occurs exactly, but also instances in which the event or circumstance occurs in a close similarity. For example, when used in conjunction with a numerical value, this term can encompass a range of variation of ±10% or less of the numerical value, such as ±5% or less, ±4% or less, ±3% or less, ±2% or less, ±1% or less, ±0.5% or less, ±0.1% or less, or ±0.05% or less.

[0313] While the present disclosure has been described by way of example in terms of preferred embodiments, it is to be understood that the disclosure is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements and procedures, and therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.

[0314] Those skilled in the art will readily appreciate that numerous alterations and modifications of the devices and methods may be made while retaining the teachings of this disclosure. Accordingly, the above disclosure should be construed as limited only by the scope and metrology of the appended claims. [Explanation of symbols]

[0315] 10 Absorption region 11 First Surface 12 Second Surface 13 Side 20 PCB 20a Foundation part 20b Upper part 20c middle part 21 First Surface 22 Second Surface 30 first electrode 40 Third electrode 60 Second electrode, third electrode 60a, 60b, 60c, 60d sub-electrode 100a, 100b, 100c, 100d, 200a, 200b, 200c, 200d, 300a, 400a, 500a, 600a, 600c, 600f, 600g, 700a, 700c, 700d, 700e, 800a, 800c, 800d, 800e, 1000a, 1000b, 1000d, 1000g, 1000h, 1000i, 1100a, 1100b, 1100d, 1200a, 1200b, 1200c, 1300a, 1300b, 1400c, 1400f, 1400g, 1400j Photodetector Devices 102, 104 first doped region 103 Second Contact Area 108 Second doped region 108a, 108b, 108c, 108d small area 130 Third Electrode 130A voltage controlled transistor 140 First electrode 141A Reset Transistor 142A Source Follower 143A Row select transistor 150A capacitor 160 Second electrode 171A transfer transistor 180 Restricted Area 181 Passage 200e, 200f Photodetector 201 Conduction Region 202 Charge layer 203 Correction Elements 204 First Contact Area 205 Recess 206 Waveguides, ridges, and trenches 208 Third Contact Area 210 intermediate doped region 212 Down-doped region 302a, 302b first doped region 303 Doped Region 330a, 330b, 330c, 330d, 330e, 330f, 330g, 330h readout electrodes 340, 340a, 340b, 340c, 340d, 340e, 340f, 340g, 340h control electrodes 350 dielectric layer 900a, 900b Photodetector 1302 Collector Area 1304 Emitter Area 1308 Basic contact area 1330 First electrode 1340 Second electrode 1360 Third Electrode 1400 protective layer 1401 First Surface 1500a, 1500b, 1500c, 1500d Gain Components 1510 Lightly doped region 1520 Emitter Area 1530 Collector Area 1540 Moderately doped region 1600a, 1600b, 1600c, 1600d Gain Components 1610 Lightly doped region 1620 Emitter Area 1630 Collector Area 1640 Basic area 1650 Moderately doped region 1700a, 1700b, 1700c, 1800a, 1800b, 1800c CMOS image sensors 1710, 1810 Lightly doped region 1720, 1820 absorption area 1722, 1822 heavily doped region 1730, 1830 Gain components, gain region 1750 Material 1900a, 1900b Photodetector 1910 Lightly doped region 1920 Absorption Area 1922 heavily doped area 1930a, 1930b Gain components, gain region 1940a, 1940b Control Area 2000a, 2000b Photodetector 2010 PCB 2020 Absorption Area 2030 Mild Dope Route 2100a Photodetector 2110 Lightly doped region 2130a, 2130b Gain components 2140a, 2140b control area 2150 board 2300a Photodetector 2310 Lightly doped region 2312 substrate 2320 Absorption Area 2322 Heavily doped region 2330a, 2330b Gain Components 2340a, 2340b control signals 2400a, 2400b Photodetector 2410 Lightly doped region 2420 Light absorption area 2422 Heavily doped region 2430a, 2430b Gain Components 2440a, 2440b Control area, control signal 2450 board 2460 Mild Dope Route AR absorption region B Basic electrode C Collector electrode C1, C2, C3, C4 control area d. Shortest distance between the first electrode 30 and the side surface 13, distance between the first electrode 30 and the side surface 13 D1: A direction substantially perpendicular to the first surface 21 E emitter electrode, emitter signal IA1 Photocurrent M multiplication region M1, M2 control terminal, control signal TG1 switching signal VA1 constant voltage VC1 Control voltage VOUT1 output voltage V0 voltage w1 Width of the absorption region 10 w2 Width of the second doped region 108 Y direction

Claims

1. A light detection apparatus comprising a light detection device, the light detection device comprising: a carrier conducting layer having a first surface and a second surface opposite the first surface; an absorption region in contact with the carrier conducting layer and configured to receive an optical signal and generate photocarriers in response to the optical signal; the absorber region is doped with a first dopant having a first conductivity type and a first peak doping concentration; the carrier conduction layer is doped with a second dopant having a second conductivity type and a second peak doping concentration; the carrier conduction layer comprises a material different from a material of the absorbing region; the carrier conduction layer is in contact with the absorber region to form at least one heterointerface; an absorber region, wherein a ratio between the first peak doping concentration of the absorber region and the second peak doping concentration of the carrier conduction layer is 10 or greater; a first electrode formed on the first surface of the carrier conduction layer and electrically coupled to the carrier conduction layer, the first electrode being separated from the absorbing region and configured to collect a portion of the photocarriers; a second electrode formed on the first surface of the carrier conduction layer and electrically coupled to the absorber region; and A light detection device comprising:

2. 2. The photodetector device of claim 1, wherein the carrier conduction layer comprises a first doped region separated from the absorber region, the first doped region having a conductivity type different from that of the absorber region, the first doped region being doped with a third dopant having a third peak doping concentration higher than the second peak doping concentration, and the first electrode being electrically coupled to the first doped region.

3. 3. The photodetector device of claim 2, wherein the carrier conduction layer comprises a conduction region having the second dopant, the conduction region having a depth of less than 5 μm, the conduction region being formed between the first doped region and the absorption region for transporting a portion of the photocarriers from the absorption region to the first doped region.

4. The photodetector device of claim 3 , wherein the carrier conducting layer is a substrate, and the absorbing region is at least partially embedded in the substrate.

5. 2. The photodetector device of claim 1, wherein the absorption region comprises a first surface, a second surface opposite to the first surface, and one or more side surfaces between the first surface and the second surface, and a shortest distance between the first electrode and the one or more side surfaces of the absorption region is between 0.1 μm and 20 μm.

6. 2. The photodetector device of claim 1, wherein the absorption region comprises a first surface, a second surface opposite the first surface, and one or more side surfaces between the first surface and the second surface, and at least a portion of the first surface, the second surface, and / or the one or more side surfaces are in contact with the carrier conduction layer.

7. 10. The photodetector device of claim 1, wherein the absorption region is doped with a graded doping profile.

8. At least 50% of the absorbent area is 1×10 １６ cm －３ 2. The photodetector device according to claim 1, wherein the photodetector device is doped with the first dopant at a doping concentration of at least 1000 .mu.m.

9. the doping concentration of the first dopant at the heterointerface between the absorption region and the carrier conduction layer is 1×10 １６ cm －３ The photodetector according to claim 1 .

10. 2. The photodetector device of claim 1, wherein the first conductivity type of the first dopant and the second conductivity type of the second dopant are different, and a ratio of a doping concentration of the absorption region to a doping concentration of the carrier conduction layer at the heterointerface is 10 or greater.

11. 2. The photodetector device of claim 1, further comprising: a second doped region in the carrier conduction layer in contact with the absorption region, the second doped region having the same conductivity type as the first conductivity type and doped with a fourth dopant having a fourth peak doping concentration higher than the first peak doping concentration; and the second electrode electrically coupled to the second doped region.

12. 12. The photodetector device of claim 11, wherein a portion of the second doped region is covered by the absorbing region, the absorbing region has a width, and the width of the second doped region covered by the absorbing region is equal to or greater than half of the width of the absorbing region.

13. 10. The optical detection device of claim 1, wherein the carrier conducting layer further comprises a waveguide configured to guide and confine the optical signal propagating through a defined region of the carrier conducting layer for coupling the optical signal to the absorption region.

14. A light detection apparatus comprising a light detection device, the light detection device comprising: a carrier conducting layer having a first surface and a second surface opposite the first surface; an absorption region in contact with the carrier conducting layer and configured to receive an optical signal and generate photocarriers in response to the optical signal; the absorber region is doped with a first dopant having a first conductivity type and a first peak doping concentration; the carrier conduction layer is doped with a second dopant having a second conductivity type and a second peak doping concentration; the carrier conduction layer comprises a material different from a material of the absorbing region; the carrier conduction layer is in contact with the absorber region to form at least one heterointerface; an absorber region, wherein a ratio between the first peak doping concentration of the absorber region and the second peak doping concentration of the carrier conduction layer is 10 or greater; one or more switches electrically coupled to the absorption region and partially formed in the carrier conduction layer, one or more multiplexed switches, each of which comprises a control electrode and a readout electrode formed on the first surface and separated from the absorption region; an electrode formed on the first surface and electrically coupled to the absorbing region; A light detection device comprising:

15. 15. The photodetector device of claim 14, wherein the control electrode and the readout electrode of the one or more switches are located on one side of the absorption region.

16. 15. The photodetector device of claim 14, wherein the carrier conduction layer comprises a conduction region having the second dopant, the conduction region having a depth of less than 5 μm, the conduction region being formed between the first doped region and the absorption region for transporting a portion of the photocarriers from the absorption region to the first doped region.

17. 15. The photodetector device of claim 14, wherein the absorption region comprises a first surface, a second surface opposite the first surface, and one or more side surfaces between the first surface and the second surface, and at least a portion of the first surface, the second surface, and / or the one or more side surfaces are in contact with the carrier conduction layer.

18. At least 50% of the absorbent area is 1×10 １６ cm －３ 15. The photodetector device of claim 14, wherein the photodetector device is doped with a doping concentration of the first dopant of at least 1000 .mu.m.

19. 15. The photodetector device of claim 14, further comprising a second doped region in the carrier conduction layer in contact with the absorption region, the second doped region having the same conductivity type as the first conductivity type and doped with a fourth dopant having a fourth peak doping concentration higher than the first peak doping concentration, and the electrode electrically coupled to the second doped region.

20. 15. The photodetector device of claim 14, wherein the first conductivity type of the first dopant and the second conductivity type of the second dopant are different, and a ratio between a doping concentration of the absorbing region and a doping concentration of the carrier conduction layer at the at least one heterointerface is 10 or greater.

Images