Photo-detecting apparatus

Abstract

This application provides a photodetector. In one embodiment, the photodetector includes a substrate, an absorption region supported by the substrate and configured to receive an optical signal and generate photocarriers in response to the optical signal, and multiple sets of switches including a first group and a second group. The substrate includes a first material, and the absorption region includes a second material. The absorption region is disposed between the first group and the second group of switches. Each set of switches individually includes a control region and a readout region. The control region of the multiple sets of switches is configured to receive a control signal, and the individual readout regions of the multiple sets of switches are configured to provide one or more electrical signals, one or more electrical signals representing first set information, for acquiring time-of-flight information related to the optical signal.

Description

Technical Field

[0001] This application relates primarily to a detection device. Specifically, this application provides a light detection device. Prior Technology

[0002] Optical detectors are used to detect optical signals and convert them into electrical signals that can be processed by other circuit systems. Optical detectors can be used in consumer electronics, proximity sensing, biometric sensing, image sensing, 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

[0003] The various forms and advantages of the embodiments of this application will be known and understood through the following description or by implementing the embodiments of this application.

[0004] This application describes systems, devices, apparatuses, methods, and techniques for optical detection.

[0005] One embodiment of this application provides a photodetector, comprising: a substrate including a first material; an absorption region including a second material, wherein the absorption region is supported by the substrate and configured to receive an optical signal and generate photocarriers in response to the optical signal; and a plurality of readout electrodes electrically connected to the same readout circuit. The absorption region is disposed between at least two of the plurality of readout electrodes.

[0006] Another embodiment of this application provides a photodetector, comprising: a substrate including a first material; an absorption region including a second material, wherein the absorption region is supported by the substrate and configured to receive an optical signal and generate photocarriers in response to the optical signal; and a plurality of switches, including a first group and a second group. The absorption region is disposed between the first group and the second group of switches. Each of the plurality of switches includes a control area and a readout area. The control areas of the plurality of switches are configured to receive the same control signal, and the readout areas of the plurality of switches are configured to provide one or more electrical signals representing first set information for acquiring time-of-flight information related to the optical signal.

[0007] In some embodiments, the photodetector further includes one or more carrier guiding regions at least partially formed in the substrate and in contact with the absorption region, and each of the one or more carrier guiding regions is electrically coupled to a corresponding set of switches in a plurality of sets of switches. Each of the one or more carrier guiding regions may be n-type doped.

[0008] In some embodiments, the absorption region is doped with a gradient doping distribution. The absorption region may include a first surface and a second surface located between the first surface of the absorption region and the substrate surface, and the gradient doping distribution of the absorption region may gradually decrease along the direction from the second surface of the absorption region to the first surface of the absorption region.

[0009] In some embodiments, the absorption region further includes a plurality of carrier output regions, each contacting a corresponding carrier guiding region in one or more carrier guiding regions.

[0010] In some embodiments, the absorption region belongs to a first conduction type, one or more carrier guiding regions belong to a second conduction type different from the first conduction type, the substrate belongs to the first conduction type, each control region includes a carrier control region belonging to the first conduction type, each readout region includes a carrier acquisition region belonging to the second conduction type, and one or more carrier guiding regions are separate from the carrier control region and the carrier acquisition region. The substrate may also include an anti-doped region that at least partially overlaps with one of the carrier control regions, and the anti-doped region may belong to the second conduction type.

[0011] Another embodiment of this application provides a photodetector, comprising: a substrate including a first surface and a second surface opposite to the first surface; an absorption region supported by the substrate and configured to receive an optical signal and generate photocarriers in response to the optical signal; and N sets of switches electrically coupled to the absorption region, wherein each set of switches includes a first switch and a second switch, wherein each first switch and second switch includes a control electrode disposed on the first surface and a readout electrode, and wherein N≥2. The absorption region is disposed between two sets of switches in the N sets of switches. The first switch in the N sets of switches is configured to be controlled by a first control signal to operate as a first single switch. The second switch in the N sets of switches is configured to be controlled by a second control signal different from the first control signal to operate as a second single switch.

[0012] In some embodiments, the photodetector further includes one or N carrier guiding regions at least partially formed in the substrate and in contact with the absorption region, and each of the one or N carrier guiding regions is electrically coupled to a corresponding group of switches in N groups of switches.

[0013] In some embodiments, the absorption region belongs to a first conduction type, and one or N carrier guiding regions each belong to a second conduction type different from the first conduction type. In some embodiments, the absorption region is doped with a gradient doping distribution. The absorption region may include a first surface and a second surface, wherein the second surface is located between the first surface of the absorption region and the second surface of the substrate, and the gradient doping distribution of the absorption region may gradually decrease along the direction from the second surface of the absorption region to the first surface of the absorption region. The absorption region may also include a plurality of carrier output regions in contact with the corresponding carrier guiding regions of one or N carrier guiding regions.

[0014] One or N carrier guiding regions can each be n-type doped. The substrate material can be different from the absorber material. The absorber region can contain M sides, and N sets of switches can each be respectively set on one of the corresponding sides of the M sides of the absorber region, where M≥N.

[0015] In some embodiments, the absorption region belongs to a first conduction type, one or N carrier guiding regions belong to a second conduction type different from the first conduction type, and the substrate belongs to the first conduction type. The first switch and the second switch may each include a carrier control region belonging to the first conduction type and a carrier acquisition region belonging to the second conduction type. In some embodiments, each carrier control region is located under a corresponding control electrode, each carrier acquisition region is located under a corresponding readout electrode, and one or N carrier guiding regions are separate from each carrier control region and each carrier acquisition region.

[0016] In some embodiments, the substrate further includes anti-doped regions, each anti-doped region at least partially overlapping a corresponding carrier control region, wherein the anti-doped regions belong to a second conduction type. The anti-doped regions may be separate from one or N carrier guiding regions.

[0017] In some embodiments, the depth of one or N carrier guiding regions is less than the depth of the absorption region. In some embodiments, the absorption region is located between one or N carrier guiding regions.

[0018] In some embodiments, the individual readout electrodes of the plurality of switches are configured to provide one or more electrical signals representing information of a first set for acquiring time-of-flight information related to the optical signal.

[0019] Another embodiment of this application provides a photodetector, comprising: a substrate having a first surface and a second surface opposite to the first surface; an absorption region supported by the substrate and configured to receive optical signals and generate photocarriers in response to optical signals, wherein the absorption region and the substrate belong to a first conduction type; one or more photocarrier guiding regions, at least partially formed in the substrate and in contact with the absorption region, wherein the one or more photocarrier guiding regions belong to a second conduction type different from the first conduction type; and one or more sets of switches electrically coupled to the absorption region, wherein each set of switches in the one or more sets of switches includes a first switch and a second switch. Each of the first and second switches includes a control electrode and a readout electrode disposed on the first surface. Each of the first and second switches includes a photocarrier acquisition region located under a corresponding readout electrode and a control electrode located under a corresponding photocarrier control region, and the one or more photocarrier guiding regions are separate from each photocarrier acquisition region and each photocarrier control region.

[0020] In some embodiments, the substrate further includes anti-doped regions, each at least partially overlapping the corresponding carrier control region, and the anti-doped regions are of a second conduction type. The anti-doped regions may be separate from one or more carrier guiding regions.

[0021] In some implementations, the depth of one or more carrier guiding regions is less than the depth of the absorption region.

[0022] In some embodiments, the absorption region is doped with a gradient doping distribution. The absorption region includes a first surface and a second surface, wherein the second surface is located between the first surface of the absorption region and a second surface of the substrate, and the gradient doping distribution of the absorption region gradually decreases along the direction from the second surface of the absorption region to the first surface of the absorption region. The absorption region may also include a plurality of carrier output regions, each contacting a corresponding carrier guiding region in one or more carrier guiding regions.

[0023] In some embodiments, the substrate material differs from the material of the absorption region. In some embodiments, the individual readout electrodes of the plurality of switches are configured to provide one or more electrical signals representing first set information for acquiring time-of-flight information associated with the optical signal.

[0024] Another embodiment of this application provides a photodetector, comprising: a substrate including a first surface and a second surface opposite to the first surface; an absorption region supported by the substrate and configured to receive an optical signal and generate one or more photocarriers in response to the optical signal, wherein the absorption region belongs to a first conduction type; a first contact region electrically coupled to the absorption region; and N sets of gain components, each including: a plurality of second contact regions, each of the first conduction type and formed in the substrate, and a plurality of third contact regions, each having a second conduction type different from the first conduction type and formed in the substrate. At least two of the N sets of gain components are respectively disposed on two opposite sides of the absorption region. The plurality of second contact regions are configured to be applied to a first voltage, and the plurality of third contact regions are configured to be applied to a second voltage.

[0025] In some embodiments, the photodetector further includes a plurality of multiplication regions formed between a respective second contact region and a respective third contact region, which are capable of generating one or more additional charge carriers upon receiving one or more photocarriers generated by the absorption region. At least two of the plurality of multiplication regions may be formed on opposite sides of the absorption region.

[0026] In some embodiments, the absorption region is doped with a gradient doping distribution. The absorption region includes a first surface and a second surface, wherein the second surface is located between the first surface of the absorption region and the second surface of the substrate, and the gradient doping distribution of the absorption region may gradually decrease along the direction from the second surface of the absorption region to the first surface of the absorption region.

[0027] In some embodiments, the photodetector further includes one or more carrier guiding regions formed in the substrate and in contact with the absorption region, and each of the one or more carrier guiding regions is electrically coupled to a corresponding group of N groups of gain components.

[0028] In some embodiments, the absorption region further includes one or more carrier output regions, each contacting a corresponding carrier guiding region in one or more carrier guiding regions, and the one or more carrier output regions are doped with the lowest doping concentration in the absorption region.

[0029] In some embodiments, the substrate material differs from the material of the absorption region. In some embodiments, the third contact region is configured to provide one or more electrical signals representing information from the first set for acquiring time-of-flight information related to the optical signal.

[0030] Another embodiment of this application provides a photodetector, comprising: a substrate having a first surface and a second surface opposite to the first surface; an absorption region supported by the substrate and configured to receive optical signals and generate photocarriers in response to optical signals, wherein the absorption region and the substrate belong to a first conduction type; one or more carrier guiding regions, at least partially formed in the substrate and in contact with the absorption region, wherein the one or more carrier guiding regions belong to a second conduction type different from the first conduction type; and one or more sets of switches electrically coupled to the absorption region, wherein each set of switches individually includes a control electrode and a readout electrode disposed on the first surface, a carrier acquisition region located under the corresponding readout electrode, and an individual carrier control region located under the corresponding control electrode, wherein the one or more carrier guiding regions are separate from each carrier acquisition region and each carrier control region.

[0031] Another embodiment of this application provides a sensing module, including a transmitter unit, a receiver unit, and a signal processor electrically communicating with the receiver unit; and a controller electrically communicating with the processor and the transmitter unit; wherein the receiver unit includes one or more photodetectors as described in this application. In some embodiments, the sensing module may be a proximity sensing module or a Time-of-Flight (TOF) sensing module.

[0032] Details of one or more disclosed embodiments are set forth in the accompanying drawings and the following description. Other features, features, and advantages will become apparent from the description, drawings, and claims. Simple Explanation of the Diagram

[0033] The following detailed description, together with the accompanying drawings, will enable the reader to more easily understand and comprehend the above-mentioned features and the many advantages of this application, as shown in the drawings: Figure 1A is a top view depicting a light detection device according to one or more embodiments of this application; Figure 1B is a cross-sectional view along line A-A' in Figure 1A according to one or more embodiments of this application; Figure 1C is a top view depicting a light detection device according to one or more embodiments of this application; Figure 1D is a top view depicting a light detection device according to one or more embodiments of this application; Figure 1E is a cross-sectional view along line A-A' in Figure 1D according to one or more embodiments of this application; Figure 1F depicts a gradient doping distribution along the C-C' line in Figure 1E according to one or more embodiments of this application; Figure 1G is a cross-sectional view along line C-C' in Figure 1E according to one or more embodiments of this application; Figure 2A is a top view depicting a light detection device according to one or more embodiments of this application; Figure 2B is a cross-sectional view along line A-A' in Figure 2A according to one or more embodiments of this application; Figure 2C is a cross-sectional view along line B-B' in Figure 2A according to one or more embodiments of this application; Figure 2D is a top view depicting a light detection device according to one or more embodiments of this application; Figure 2E is a top view depicting a light detection device according to one or more embodiments of this application; Figure 2F is a cross-sectional view along line B-B' in Figure 2E according to one or more embodiments of this application; Figure 2G is a top view depicting a light detection device according to one or more embodiments of this application; Figure 2H is a top view depicting a light detection device according to one or more embodiments of this application; Figure 2I is a top view depicting a light detection device according to one or more embodiments of this application; Figure 3A is a top view depicting a light detection device according to one or more embodiments of this application; Figure 3B is a cross-sectional view along line A-A' in Figure 3A according to one or more embodiments of this application; Figure 4A is a top view depicting a light detection device according to one or more embodiments of this application; Figure 4B is a cross-sectional view along line A-A' in Figure 4A according to one or more embodiments of this application; Figure 4C is a top view depicting a light detection device according to one or more embodiments of this application; Figure 4D is a cross-sectional view along line A-A' in Figure 4C according to one or more embodiments of this application; Figure 4E is a top view depicting a light detection device according to one or more embodiments of this application; Figure 4F is a cross-sectional view along line A-A' in Figure 4E according to one or more embodiments of this application; Figures 5A-5C are partial cross-sectional views depicting a photodetector according to one or more embodiments of this application; Figures 6A-6D show examples of control areas C1a, C1b, C1c, C1d, C2a, C2b, C2c, and C2d of a photodetector according to one or more embodiments of this application; Figure 7A is a block diagram of an exemplary embodiment of an imaging system according to one or more embodiments of this application; and Figure 7B is a block diagram showing an exemplary receiver unit or controller according to one or more embodiments of this application. Similar components are represented using similar reference numerals and names. Implementation

[0034] The benefit claimed in this application is based on U.S. Provisional Patent Application No. 63 / 163,057, filed on March 19, 2021, the entire contents of which are incorporated herein by reference.

[0035] In this document, terms such as "first," "second," "third," "fourth," and "fifth" may describe various elements, components, regions, layers, and / or parts, which should not be limited to these terms. These terms may only be used to distinguish different elements, components, regions, layers, or parts. Unless the context otherwise indicates, the use of terms such as "first," "second," "third," "fourth," and "fifth" in this document does not indicate a specific order or sequence. Terms such as "light detection," "light sensing," "ray beam detection," and any other similar terms may be used interchangeably.

[0036] Spatial descriptions, such as "above," "top," and "bottom," etc., unless otherwise specified, indicate orientation with respect to what is shown in the figures. It should be understood that the spatial descriptions used herein are for illustrative purposes only, and actual implementations of the structures described herein may be arranged in different orientations or arrangements in space, as long as the advantages of the embodiments of this application do not depart from such arrangement.

[0037] In this article, "essence" means that the semiconductor material has not been intentionally doped.

[0038] Figure 1A depicts a top view of the light detection device 100a according to one or more embodiments. Figure 1B depicts a cross-sectional view along line A-A' in Figure 1A according to one or more embodiments.

[0039] The photodetector 100a includes a substrate 20 having a first material and an absorption region 10 having a second material, the absorption region 10 being supported by the substrate 20. In some embodiments, the absorption region 10 includes an optical signal receiving region AR, defined by a light shield (not shown) having an optical window. The optical signal receiving region AR is a virtual area that receives incident optical signals passing through the optical window. The absorption region 10 is configured to receive optical signals and generate photocarriers in response to the optical signals.

[0040] In some embodiments, the substrate 20 includes a first surface 21 and a second surface 22 opposite to the first surface 21. In some embodiments, the absorption region 10 includes a first surface 11, a second surface 12, and one or more side surfaces 13. The second surface 12 of the absorption region 10 is located between the first surface 11 of the absorption region 10 and the second surface 22 of the substrate 20. At least one of the first surface 11, the second surface 12, and the one or more side surfaces 13 of the absorption region 10 is at least partially in direct contact with the substrate 20, thus forming a heterogeneous interface between the absorption region 10 and the substrate 20.

[0041] In some embodiments, as shown in FIG1A, the photodetector 100a has multiple sets of switches, including a first set of switches 102a and a second set of switches 102b, and the absorption region 10 is disposed between the first set of switches 102a and the second set of switches 102b. The first set of switches 102a and the second set of switches 102b each include a control region C1a, C1b and a readout region R1a, R1b.

[0042] In some embodiments, readout regions R1a and R1b each include readout electrodes 330a and 330b disposed on the first surface 21 of the substrate 20. In some embodiments, as shown in FIG1B, readout regions R1a and R1b each also include carrier acquisition regions 302a and 302b located below the respective readout electrodes 330a and 330b.

[0043] In some embodiments, as shown in FIG1B, the control regions C1a and C1b of the first group of switches 102a and the second group of switches 102b in the plurality of switches are coupled to the control unit 110 and configured to receive the same control signal from the control unit 110. In some embodiments, as shown in FIG1A and 1B, the control regions C1a and C1b each include control electrodes 340a and 340b disposed on the first surface 21 of the substrate 20 and electrically coupled to the control unit 110. That is, the plurality of switches (e.g., the first group of switches 102a and the second group of switches 102b) controlled by the same control signal from the control unit 110 operate together as a single switch. The single switch is electrically connected to the same absorption region 10 or the same optical signal receiving region AR, thereby controlling the flow direction of photocarriers from the same absorption region 10 or the same optical signal receiving region AR and collecting photocarriers from the same absorption region 10 or the same optical signal receiving region AR.

[0044] By placing the absorption region 10 between a first set of switches 102a and a second set of switches 102b, which are controlled by the same control signal from the control unit 110, the photocarriers generated in the absorption region 10 can be collected by one of the readout electrodes 330a and 330b of the readout regions R1a and R1b, which are closer to the photocarriers to be collected in the absorption region 10. In this way, the travel distance of the photocarriers can be shortened, thereby increasing the speed of the photodetector 100a.

[0045] In some embodiments, as shown in FIG1B, the readout regions R1a, R1b of the first group of switches 102a and the second group of switches 102b are coupled to a readout circuit 112 and configured to provide one or more electrical signals to the readout circuit 112. The one or more electrical signals may represent a first set of information for obtaining time-of-flight (TOF) information related to the optical signal.

[0046] In some embodiments, the readout circuit 112 may employ a tri-transistor configuration having a reset gate, a source follower, and a selection gate, or a quad-transistor configuration, including a transmission gate, or any suitable circuitry capable of processing the charge collected in the readout region. In some embodiments, multiple sets of switches are electrically coupled to the same readout circuit 112 and jointly output a single signal; for example, the first set of switches 102a and the second set of switches 102b may jointly output a single overall output signal.

[0047] In some embodiments, the photodetector 100a further includes one or more carrier guiding regions 201a and 201b, at least partially formed in the substrate 20 and in contact with the absorption region 10. Each carrier guiding region 201a, 201b is electrically coupled to a corresponding group of switches in a plurality of groups of switches. For example, referring to FIG1A, carrier guiding region 201a is electrically coupled to a first group of switches 102a, and carrier guiding region 201b is electrically coupled to a second group of switches 102b.

[0048] In some embodiments, the absorption region 10 is doped with a first conduction type (e.g., p-doped), and the carrier guiding regions 201a and 201b are doped with a second dopant, which is different from the first conduction type and belongs to a second conduction type (e.g., n-type doped). In some embodiments, the substrate 20 is doped with a first conduction type dopant. The carrier guiding regions 201a and 201b may be configured to restrict the path of photocarriers generated from the same absorption region 10 or the same optical signal receiving region AR toward the first set of switches 102a and / or the second set of switches 102b. In some embodiments, the peak doping concentrations of the carrier guiding regions 201a and 201b are both between 1 x 10¹² cm⁻³ and 1 x 10¹⁸ cm⁻³.

[0049] In some embodiments, at the heterojunction between one or more carrier guiding regions 201a, 201b and absorption region 10, the ratio of the doping concentration of the first dopant in absorption region 10 to the doping concentration of the second dopant in one or more carrier guiding regions 201a, 201b is equal to or greater than 10, thereby enabling the photodetector 100a to achieve good quantum efficiency while reducing dark current on the heterojunction.

[0050] In some embodiments, such as shown in FIG. 1B, the photodetector 100a further includes a first contact region 108 located in and near the first surface 11 of the absorption region 10. The first contact region 108 is doped with the same conduction type as the absorption region 10 (e.g., p-type doping). In some embodiments, the peak doping concentration in the first contact region 108 is higher than the peak doping concentration in the absorption region 10. For example, the peak doping concentration of the first contact region 108 may be between 1 x 10¹⁸ cm⁻³ and 5 x 10²⁰ cm⁻³. The carriers collected by the first contact region 108 are different from those collected by the carrier collection regions 302a and 302b. For example, if the carrier collection region 302a is n-type doped for collecting electrons, then the first contact region 108 is p-type doped for collecting holes.

[0051] In some embodiments, such as shown in FIG1B, the photodetector 100a further includes a first electrode 60 electrically coupled to the first contact region 108. Depending on the material of the first electrode 60 and the peak doping concentration of the first contact region 108, an ohmic contact may be formed between the first electrode 60 and the first contact region 108. The first electrode 60 is disposed on the first surface 11 of the absorption region 10.

[0052] In some embodiments, the first contact area 108 may be formed in the substrate 20 and in contact with the absorption area 10, while the first electrode 60 is disposed on the first surface 21 of the substrate 20. For details, please refer to Figures 2E and 2I simultaneously.

[0053] Figure 1C depicts a top view of the light detection device 100c according to one or more embodiments of the present application. According to one or more embodiments of the present application, the cross-sectional view along line A-A' in Figure 1C is similar to that in Figure 1B. Elements similar to those described above are indicated using similar reference numerals and names. Differences are explained below.

[0054] Compared to the photodetector 100a with two sets of switches in Figures 1A-1B, the photodetector 100c includes four sets of switches. As shown in Figure 1C, the absorption region 10 is disposed between the four sets of switches. All four sets of switches are controlled by the same control signal from the control unit 110. The four sets of switches are electrically coupled to the same readout circuit 112 and jointly output a single signal, for example, all four sets of switches jointly output a single overall output signal. In some embodiments, the number of sets of switches in the photodetector is not limited to two or four sets. The number of sets can be a positive integer not less than 2.

[0055] Figure 1D depicts a top view of the photodetector 100d according to one or more embodiments of the present application. Figure 1E depicts a cross-sectional view along line A-A' in Figure 1D according to one or more embodiments of the present application. Figure 1F depicts a gradient doping distribution along line C-C' in Figure 1E according to one or more embodiments of the present application. Similar elements to those described above are indicated using similar reference numerals and names. Differences are explained below.

[0056] In some embodiments, the absorption region 10 is doped with a gradient doping distribution such that at least a portion of the absorption region 10 in contact with one or more carrier guiding regions 201a, 201b along the horizontal direction has the lowest doping concentration in the absorption region 10. The horizontal direction is substantially parallel to the first surface 21 of the substrate 20. In some embodiments, the gradient doping distribution of the absorption region 10 gradually decreases along the direction from the second surface 12 of the absorption region 10 to the first surface 11 of the absorption region 10. In some embodiments, the absorption region 10 is completely embedded in the substrate 20. For example, referring to Figures 1E and 1F, the absorption region 10 may comprise multiple layers, such as, but not limited to, three layers 101, 102, and 103, each with different peak doping concentrations A, B, and C. Layer 102 is located between layers 101 and 103. Peak doping concentration A is higher than peak doping concentration B, and peak doping concentration B is higher than peak doping concentration C. Referring to Figure 1F, the gradient doping distribution may be a step-like concentration distribution. In another example, referring to Figure 1G, the gradient doping distribution can be a gradient distribution. Since the gradient doping distribution of the absorption region 10 gradually decreases along the direction from the second surface 12 of the absorption region 10 to the first surface 11 of the absorption region 10, the carriers to be collected (e.g., electrons, when the carrier guiding regions 201a, 201b are n-type doped) can be driven to move toward one or more carrier guiding regions 201a, 201b that are close to the first surface 11 of the absorption region 10.

[0057] In some embodiments, as shown in Figures 1D and 1E, the absorption region 10 further includes a plurality of carrier output regions 104a and 104b, each contacting a corresponding carrier guiding region 201a and 201b. In some embodiments, the peak doping concentration of the carrier output regions 104a and 104b is lower than the peak doping concentration C of the bulk absorption region 10. The carrier output regions 104a and 104b further promote carrier migration from the absorption region 10 to the carrier guiding regions 201a and 201b.

[0058] Figure 2A depicts a top view of the light detection device 200a according to one or more embodiments of the present application. Figure 2B depicts a cross-sectional view along line A-A' in Figure 2A according to one or more embodiments of the present application. Figure 2C depicts a cross-sectional view along line B-B' in Figure 2A according to one or more embodiments of the present application. In some embodiments, the cross-sectional view along line C-C' in Figure 2A is similar to the cross-sectional view in Figure 2B, but the reference numerals may differ. Similar elements are denoted using similar reference numerals and names. The light detection device 200a of the present application will now be described in detail.

[0059] In some embodiments, the photodetector 200a includes multiple sets of switches 102a, 102b. The absorption region 10 is supported by the substrate 20 and configured to receive optical signals and generate photocarriers in response to optical signals. In some embodiments, the photodetector 200a includes N sets (N≥2) of switches electrically coupled to the absorption region 10, wherein each set of switches 102a, 102b individually includes a first switch S1a, S1b and a second switch S2a, S2b. The first switch S1a, S1b and the second switch S2a, S2b each include a control electrode 340a, 340b, 360a, 360b and a readout electrode 330a, 330b, 370a, 370b disposed on the first surface 21. For example, the first set of switches 102a includes the first switch S1a and the second switch S2a, and the second set of switches 102b includes the first switch S1b and the second switch S2b. The first switch S1a may include a control electrode 340a and a readout electrode 330a. The second switch S2a may include a control electrode 360a and a readout electrode 370a. The first switch S1b may include a control electrode 340b and a readout electrode 330b. The second switch S2b may include a control electrode 360b and a readout electrode 370b.

[0060] Absorption region 10 can be disposed between two groups of N switches, such as the two groups of switches 102a and 102b in Figure 2A. For example, referring to Figure 2A, absorption region 10 is disposed between two groups of switches 102a and 102b. The first switches S1a and S1b of the N groups of switches are controlled by a first control signal and can operate together as a single switch, for example, a first single switch. The second switches S2a and S2b of the N groups of switches are controlled by a second control signal different from the first control signal and can operate together as another single switch, for example, a second single switch. The first single switch and the second single switch are electrically connected to the same absorption region 10 or the same optical signal receiving region AR, thereby controlling the flow direction of photocarriers from the same absorption region 10 or the same optical signal receiving region AR and collecting photocarriers from the same absorption region 10 or the same optical signal receiving region AR.

[0061] By placing the absorption region 10 between at least two of the N sets of switches, where the first switches S1a and S1b of the two sets of switches are controlled by the same first control signal, and the second switches S2a and S2b of the two sets of switches are controlled by the same second control signal, when the first switches S1a and S1b are open, the photocarriers generated by the absorption region 10 can be collected by the one closer to the photocarriers to be collected in the absorption region 10 among the readout electrodes 330a and 330b of the first switches S1a and S1b. When the second switches S2a and S2b are open, the photocarriers generated by the absorption region 10 can be collected by the one closer to the photocarriers to be collected in the absorption region 10 among the readout electrodes 370a and 370b of the second switches S2a and S2b. In this way, the travel distance of the photocarriers is shortened, and the speed of the photodetector 200a can be increased. The photocarriers collected by all the first switches S1a and S1b can be processed together to operate as a single switch, and the photocarriers collected by all the second switches S2a and S2b can be processed together to operate as another single switch. Although not shown in the figures, the multiple sets of switches depicted in Figures 2A to 2C can also be implemented using more than two switches.

[0062] In some embodiments, the photodetector 200a includes one or more carrier guiding regions 201a, 201b, which are at least partially formed in the substrate 20 and in contact with the absorption region 10. Each of the one or more carrier guiding regions 201a, 201b is electrically coupled to a corresponding group switch 102a, 102b in the N groups of switches.

[0063] In some embodiments, the photodetector 200a further includes one or more readout circuits electrically connected to individual switches (e.g., the first readout circuit 112a and the second readout circuit 112b of FIG. 2B). In some embodiments, photocarriers collected by the first switches S1a and S1b of the N sets of switches can be processed together by the first readout circuit, and photocarriers collected by the second switches S2a and S2b of the N sets of switches can be processed together by the second readout circuit. In some embodiments, the first or second readout circuit may employ a three-transistor configuration having a reset gate, a source follower, and a selection gate, or a four-transistor configuration, including a transmission gate, or any suitable circuit system capable of processing the collected charges.

[0064] In some embodiments, the first control signal and the second control signal respectively control the control regions C1a and C1b of the first switches S1a and S1b and the control regions C2a and C2b of the second switches S2a and S2b, to control the movement direction of electrons or holes generated by photons absorbed in the absorption region 10. In some embodiments, the first control signal and the second control signal are different. For example, when different voltages are provided using the control signals to generate a bias voltage, an electric field will be generated between the two parts directly below the control electrodes of individual switches. For example, an electric field will be generated between the two parts directly below the control electrodes 340a and 340b of the first switches S1a and S1b and the two parts directly below the control electrodes 360a and 360b of the second switches S2a and S2b, as well as in the absorption region 10. Free carriers within the absorption region 10 drift towards the portion directly below one of the readout electrodes 330a, 330b, 370a, 370b, depending on the direction and distance of the electric field, and are then collected by the readout electrodes 330a, 330b, 370a, 370b. For example, when a bias voltage is generated by providing different voltages using a control signal, the first switches S1a and S1b are turned on, thereby generating an electric field that drives the photocarriers in the absorption region 10 to flow towards the readout electrodes 330a and 340a. The photocarriers are then collected by the readout electrode 330a and 340a that is closer to the photocarriers to be collected in the absorption region 10. The collected photocarriers are then further processed by the same readout circuit (e.g., the first readout circuit 112a) electrically coupled to the readout electrodes 330a and 340a. Therefore, the travel distance of the photocarriers is shortened, which can increase the speed of the photodetector 200a.

[0065] In some embodiments, the first control signal includes a first control phase, and the second control signal includes a second control phase, wherein the first control phase does not overlap with the second control phase. In some embodiments, the first control signal is fixed at a voltage value V, and the second control signal alternates between voltage values ​​V ± ΔV. In some embodiments, ΔV is generated by a varying voltage signal, such as a sinusoidal signal, clock signal, or pulse signal operating between 0V and 3V. The drift direction of the carriers generated in the absorption region 10 depends on the bias voltage direction. In some embodiments, the control signal is a modulation signal.

[0066] Referring to FIG2C, in some embodiments, the absorption region 10 is at least partially embedded in the substrate 20. In some embodiments, the depth d1 of one or more carrier guiding regions 201a, 201b in the substrate 20 is less than the depth d2 of the absorption region 10 in the substrate 20. Since the depth d1 of one or more carrier guiding regions 201a, 201b is less than the depth d2 of the absorption region 10, the interface area between the carrier guiding region 201a and the absorption region 10 is reduced, thereby reducing the dark current of the photodetector 200a.

[0067] Figure 2D depicts a top view of a photodetector 200d according to one or more embodiments of this application. The photodetector 200d may be similar to the photodetector 200a of Figures 2A-2C. However, unlike the photodetector 200a, the photodetector 200d includes an absorption region 10 using a gradient doping distribution, as shown in Figures 1D, 1E, 1F, or 1G. For example, similar to the absorption region 10 of the photodetector 100d in Figures 1D and 1E, in the photodetector 200d, the absorption region 10 may include a plurality of carrier output regions 104a, 104b, each contacting a corresponding carrier guiding region 201a, 201b. In some embodiments, the peak doping concentration of the carrier output regions 104a, 104b is lower than the peak doping concentration C of the absorption region 10 body. The carrier output regions 104a and 104b further promote the movement of carriers from the absorption region 10 to the carrier guiding regions 201a and 201b.

[0068] Figure 2E depicts a top view of the photodetector 200e according to one or more embodiments of the present application. Figure 2F depicts a cross-sectional view along line B-B' in Figure 2E according to one or more embodiments of the present application. The photodetector 200e may be similar to the photodetector 200a of Figures 2A-2C. The cross-sectional views along lines A-A' and C-C' in Figure 2E may be similar to the cross-sectional views in Figure 2B, but the reference numerals may differ. Similar elements to those described above are indicated using similar reference numerals and names. The differences are explained below.

[0069] Compared to the photodetector 200a, which has a first contact area 108 formed in the absorption region 10, the photodetector 200e, as shown in FIG2E, may include multiple first contact areas 108 formed in the substrate 20 and in contact with the absorption region 10. Multiple first electrodes 60 may be disposed on the first surface 21 of the substrate 20 and electrically coupled to the corresponding first contact areas 108. Since the first electrodes 60, readout electrodes 330a, 330b, 370a, 370b, and control electrodes 340a, 340b, 360a, 360b can be formed on the same first surface 21 of the substrate 20, the height difference between the electrodes can be reduced.

[0070] Figure 2G depicts a top view of a light detection device 200g according to one or more embodiments of this application. The light detection device 200g may be similar to the light detection device 200a of Figures 2A-2C. Similar elements are indicated by similar reference numerals and names. The differences are explained below.

[0071] In some embodiments, the absorption region 10 includes M sides, and N sets of switches are each disposed on one side of the absorption region 10, where M and N are integers and M ≥ N. For example, referring to FIG2G, the absorption region 10 includes four sides. Four sets of switches 102a, 102b, 102c, and 102d are each disposed on one of these four sides. In some embodiments, the absorption region 10 is located between the carrier guiding regions 201a, 201b, 201c, and 201d.

[0072] There are four groups of switches 102a, 102b, 102c, and 102d, and four carrier guidance regions 201a, 201b, 201c, and 201d. In some embodiments, the number of switch groups is not limited to two or four. The number of groups is a positive integer and ≥2.

[0073] As shown in Figure 2G, the first set of switches 102a includes: a first switch S1a having a first control region C1a containing a control electrode 340a and a first readout region R1a containing a readout electrode 330a; and a second switch S2a having a second control region C2a containing a control electrode 360a and a second readout region R2a containing a readout electrode 370a. The second set of switches 102b includes: a first switch S1b having a first control region C1b containing a control electrode 340b and a first readout region R1b containing a readout electrode 330b; and a second switch S2b having a second control region C2b containing a control electrode 360b and a second readout region R2b containing a readout electrode 370b. The third set of switches 102c includes: a first switch S1c having a first control region C1c including a control electrode 340c and a first readout region R1c including a readout electrode 330c; and a second switch S2c having a second control region C2b including a control electrode 360c and a second readout region R2c including a readout electrode 370c. The fourth set of switches 102d includes: a first switch S1d having a first control region C1d including a control electrode 340d and a first readout region R1d including a readout electrode 330d; and a second switch S2d having a second control region C2d including a control electrode 360d and a second readout region R2d including a readout electrode 370d.

[0074] In some embodiments, a first control signal controls the control regions C1a, C1b, C1c, and C1d of the first switches S1a, S1b, S1c, and S1d, and a second control signal controls the control regions C2a, C2b, C2c, and C2d of the second switches S2a, S2b, S2c, and S2d, to control the direction of movement of electrons or holes generated by photons absorbed in the absorption region 10. For example, when the first switches S1a, S1b, S1c, and S1d of the four sets of switches 102a, 102b, 102c, and 102d are turned on, photocarriers are collected by the readout electrode 330a, 330b, 330c, and 330d that is closest to the photocarriers to be collected in the absorption region 10.

[0075] Figure 2H depicts a top view of a light detection device 200h according to one or more embodiments of this application. The light detection device 200h is similar to the light detection device 200g of Figure 2G. Similar elements are indicated using similar reference numerals and names.

[0076] In the photodetector 200g, the absorption region 10 is located between four carrier guiding regions 201a, 201b, 201c, and 201d, and four sets of switches 102a, 102b, 102c, and 102d are electrically coupled to their respective carrier guiding regions 201a, 201b, 201c, and 201d. In contrast, in the photodetector 200h, the four sets of switches 102a, 102b, 102c, and 102d are electrically coupled to the same carrier guiding region 201, and the absorption region 10 is surrounded by the carrier guiding region 201.

[0077] Figure 2I depicts a top view of a light detection device 200i according to one or more embodiments of this application. The light detection device 200i is similar to the light detection device 200g of Figure 2G. Similar elements are indicated using similar reference numerals and names. The differences are explained below.

[0078] In the photodetector 200g, the first contact area 108 is formed in the absorption area 10. In contrast, in the photodetector 200i, as shown in FIG2I, multiple first contact areas 108 can be formed in the substrate 20, located outside the absorption area 10, but in contact with the absorption area 10. Multiple first electrodes 60 are disposed on the first surface 21 of the substrate 20 and electrically coupled to the corresponding first contact areas 108. Since the first electrodes 60, readout electrodes 330a, 330b, 330c, 330d, 370a, 370b, 370c, 370d, and control electrodes 340a, 340b, 340c, 340d, 360a, 360b, 360c, 360d can be formed on the same first surface 21 of the substrate 20, the height difference between the electrodes can be reduced.

[0079] Figure 3A depicts a top view of the photodetector 300a according to one or more embodiments of the present application. Figure 3B depicts a cross-sectional view along line A-A' in Figure 3A according to one or more embodiments of the present application. Similar elements to those described above are indicated using similar reference numerals and names.

[0080] The photodetector 300a includes: a substrate 20 having a first surface 21 and a second surface 22 opposite to the first surface 21; and an absorption region 10 supported by the substrate 20 and configured to receive optical signals and generate photocarriers in response to optical signals. The absorption region 10 may be doped with a dopant of a first conduction type (e.g., p-type doping).

[0081] The photodetector 300a further includes a first contact region 108 electrically coupled to the absorption region 10 and potentially doped with a first conduction type dopant. The photodetector 300a may also include N sets of gain elements 105a and 105b, each including multiple second contact regions 202a and 202b, each belonging to the first conduction type and formed in the substrate 20, and multiple third contact regions 203a and 203b, each belonging to a second conduction type different from the first conduction type (e.g., n-type doping), and formed in the substrate 20. At least two sets of gain elements 105a and 105b are respectively disposed on opposite sides of the absorption region 10, wherein the multiple second contact regions 202a and 202b are configured to be applied to a first voltage, and the multiple third contact regions 203a and 203b are configured to be applied to a second voltage.

[0082] In some embodiments, the photodetector 300a functions as an avalanche photocell. In some embodiments, the photodetector 300a further includes multiple multiplication regions Ma and Mb respectively formed between corresponding second contact regions 202a, 202b and corresponding third contact regions 203a, 203b. The multiplication regions Ma and Mb are capable of generating one or more additional charge carriers upon receiving one or more photocarriers generated by the absorption region 10. In some embodiments, at least two of the multiple multiplication regions Ma and Mb are formed on opposite sides of the absorption region 10.

[0083] By providing at least two sets of gain components 105a and 105b on opposite sides of the absorption region 10, the photocarriers generated from the absorption region 10 can be swept to the one of the multiplication regions Ma and Mb that is closer to the photocarriers in the absorption region 10, and then the photocarriers can be amplified in the multiplication regions Ma and Mb. This shortens the travel distance of the photocarriers and increases the speed of the photodetector 300a.

[0084] In some embodiments, the photodetector 300a further includes one or more carrier guiding regions 201a, 201b formed in the substrate 20 and in contact with the absorption region 10, wherein the one or more carrier guiding regions 201a, 201b are each electrically coupled to a corresponding group of N groups of gain components 105a, 105b to guide carriers to move to multiple multiplication regions Ma, Mb.

[0085] In some embodiments, the third contact areas 203a and 203b are configured to provide one or more electrical signals representing information of the first set for acquiring time-of-flight information related to the optical signal.

[0086] Figure 4A depicts a top view of the photodetector 400a according to one or more embodiments of the present application. Figure 4B depicts a cross-sectional view along line A-A' in Figure 4A according to one or more embodiments of the present application. Similar elements to those described above are indicated using similar reference numerals and names. Detailed description follows.

[0087] As shown in Figures 4A-4B, the photodetector 400a includes a control region C1a having a control electrode 340a and a readout region R1a including a readout electrode 330a located on one side of the absorption region 10. In some embodiments, the control region C1a includes a carrier control region 304a belonging to a first conduction type (e.g., p-type doping). A detailed description of the carrier control region 304a is given in Figures 6B and 6D. The photodetector 400a also includes a carrier guiding region 201 at least partially formed in the substrate 20 and in contact with the absorption region 10.

[0088] In some embodiments, the substrate 20 may further include an anti-doped region 350a that at least partially overlaps with or surrounds the carrier control region 304a, and the anti-doped region 350a may be of a second conduction type (e.g., n-type doping), which is different from the conduction type of the substrate 20. The anti-doped region 350a and the carrier guiding region 201 may have the same conduction type. In some examples, the absorption region 10 may be p-type doped, the carrier control region 304a may be p-type doped, the carrier acquisition region 302a may be n-type doped, the anti-doped region 350a may be n-type doped, and the substrate 20 may be p-type doped.

[0089] In some embodiments, at least a portion of the anti-doped region 350a is located between the carrier control region 304a and the carrier guiding region 201. In some embodiments, the anti-doped region 350a is separated from the carrier guiding region 201. By separating the carrier guiding region 201 from the carrier control region 304a, the carrier acquisition region 302a, and the anti-doped region 350a, it is easier to drive photocarriers toward the carrier control region 304a. Specifically, a high-resistivity interface can be formed between the anti-doped region 350a and the substrate 20, and photocarriers (e.g., electrons) passing through the carrier guiding region 201 can be attracted and move toward the anti-doped region 350a, and thus be demodulated by the carrier control region 304a. In some embodiments, the peak doping concentration of the anti-doped region 350a is between 1 x 10¹² cm⁻³ and 1 x 10¹⁸ cm⁻³.

[0090] Figure 4C depicts a top view of the photodetector 400c according to one or more embodiments of the present application. Figure 4D depicts a cross-sectional view along line A-A' in Figure 4C according to one or more embodiments of the present application. Similar elements are designated using similar reference numerals and names. Detailed embodiments are described below.

[0091] The photodetector 400c includes one or more carrier guiding regions 201a, 201b that are at least partially formed in the substrate 20 and contact the absorption region 10. In some embodiments, the one or more carrier guiding regions 201a, 201b belong to a second conduction type (e.g., n-type doping) that is different from the first conduction type of the absorption region 10.

[0092] In some embodiments, the photodetector 400c includes one or more sets of switches 102a, 102b electrically coupled to the absorption region 10, wherein each set of switches individually includes a control electrode 340a, 340b and a readout electrode 330a, 330b disposed on the first surface 21. Each switch 102a, 102b also includes a carrier acquisition region 302a, 302b located below the respective readout electrode 330a, 330b and a carrier control region 304a, 304b located below the respective individual control electrode 340a, 340b.

[0093] In some embodiments, one or more carrier guidance regions 201a, 201b are separated from carrier acquisition regions 302a, 302b and carrier control regions 304a, 304b.

[0094] By separating the carrier guiding regions 201a and 201b from the carrier control regions 304a and 304b and the carrier collection regions 302a and 302b, a strong electric field can be formed between each carrier collection region 302a and 302b and the substrate 20, thereby driving photocarriers to move toward the carrier control regions 304a and 304b and be collected by the carrier collection regions 302a and 302b.

[0095] Figure 4E depicts a top view of the light detection device 400e according to one or more embodiments of the present application. Figure 4F depicts a cross-sectional view of Figure 4E along line A-A' according to one or more embodiments of the present application. The cross-sectional view along line C-C' in Figure 4E may be similar to the cross-sectional view of Figure 4F, but the reference numerals may differ. The light detection device 400e is similar to the light detection device 400c of Figures 4C-4D. Unlike the light detection device 400c, which includes one switch in each of multiple sets of switches, the light detection device 400e includes multiple sets of switches, each including a first switch (e.g., S1a, S1b, S1c, or S1d) and a second switch (e.g., S2a, S2b, S2c, or S2d), as shown in Figures 2A-2I.

[0096] In some embodiments, the sectional view drawn along line C-C' in FIG4E according to one or more embodiments is similar to the sectional view in FIG4F, but the reference numerals may differ. Elements similar to those described above are denoted using similar reference numerals and names, such as those in FIG2A.

[0097] In some embodiments, as depicted in Figures 4E and 4F, the photodetector 400e includes two sets of switches 102a and 102b. The first set of switches 102a includes a first switch S1a and a second switch S2a, and the second set of switches 102b includes a first switch S1b and a second switch S2b. Each of the first switch S1a and the second switch S2a includes carrier acquisition regions 302a and 305a located below the corresponding readout electrodes 330a and 370a, and carrier control regions 304a and 306a located below the corresponding control electrodes 340a and 360a. Similarly, each of the first switch S1b and the second switch S2b may include a carrier acquisition region located below the corresponding readout electrodes 330b and 370b, and a carrier control region located below the corresponding control electrodes 340b and 360b.

[0098] The photodetector 400e includes one or more carrier guiding regions 201a, 201b, at least partially formed in the substrate 20 and in contact with the absorption region 10. The one or more carrier guiding regions 201a, 201b are separated from the carrier acquisition regions (e.g., 302a, 305a) and the carrier control regions (e.g., 304a, 306a). By separating the carrier guiding regions 201a, 201b from the carrier control regions and the carrier acquisition regions, a stronger electric field can be formed between the carrier acquisition region and the substrate 20, mitigating the coupling problem between the carrier acquisition regions (e.g., 302a, 305a) of the same group of switches (e.g., 102a) located on the same side of the absorption region 10.

[0099] In some embodiments, the substrate 20 further includes anti-doped regions 350a, 350b, 380a, and 380b, each at least partially overlapping the corresponding carrier control regions 304a and 306a, wherein the anti-doped regions 350a, 350b, 380a, and 380b belong to a second conduction type (e.g., n-type). In some embodiments, the anti-doped regions 350a, 350b, 380a, and 380b are separated from one or more carrier guiding regions 201a and 201b. In some embodiments, the carrier control regions 304a and 306a may completely overlap the corresponding anti-doped regions 350a and 380a.

[0100] By separating the carrier guiding regions 201a and 201b from the carrier control regions 304a and 306a, and by at least partially overlapping the carrier acquisition regions 302a and 305a and the anti-doped regions 350a, 350b, 380a, and 380b with the corresponding carrier control regions 304a and 306a, it is easier to drive electrons toward the carrier control regions 304a and 306a. Specifically, a high-resistivity interface can be formed between the anti-doped regions 350a, 350b, 380a, and 380b and the substrate 20. Carriers, such as electrons, moving through the carrier guiding regions 201a and 201b can be attracted and move toward the anti-doped regions 350a, 350b, 380a, and 380b, and then demodulated by the carrier control regions 304a and 306a based on the first control signal and the second control signal.

[0101] In some embodiments, photodetectors, such as 100a, 100c, 100d, 200a, 200d, 200e, 200g, 200h, 200i, 300a, 400a, 400c, or 400e, can be applied to direct or indirect TOF systems. In some embodiments, photodetectors, such as 100a, can be applied to direct TOF systems. For example, the readout electrodes of a plurality of switches (e.g., 330a, 330b, 370a, 370b in FIG. 1A) are configured to provide one or more electrical signals representing first set information for acquiring time-of-flight information related to the optical signal to be received by absorption region 10.

[0102] It should be understood that the elements mentioned herein can be combined in any manner and in any number to produce further embodiments. For example, the absorption region 10 of the photodetectors 200a, 200d, 200e, 200g, 200h, 200i, 300a, 400a, 400c, or 400e can also be doped in a gradient doping distribution, as described in Figures 1D to 1G. As another example, the absorption region 10 of the photodetectors 200a, 200d, 200e, 200g, 200h, 200i, 300a, 400a, 400c, or 400e can also include a plurality of carrier output regions 104a, 104b, as described in Figures 1D and 1E.

[0103] Figures 5A-5C show cross-sectional views of different portions of a photodetector according to one or more embodiments of this application. Each photodetector may include structures 500a, 500b, 500c, which are substantially the same as any of the above embodiments, such as 100a, 100c, 100d, 200a, 200d, 200e, 200g, 200h, 200i, 300a, 400a, 400c, or 400e.

[0104] In some embodiments, as shown in FIG. 5A, the absorption region 10 may be entirely on the first surface 21 of the substrate 20. In some embodiments, as shown in FIG. 5B, the absorption region 10 may be partially embedded in the substrate 20. In other words, a portion of the side surface of the absorption region 10 is in contact with the substrate 20. In some embodiments, as shown in FIG. 5C, the absorption region 10 may be completely embedded in the substrate 20. In other words, the side surface of the absorption region 10 is completely in contact with the substrate 20.

[0105] Figures 6A-6D show the control areas (e.g., C1a, C1b, C1c, C1d, C2a, C2b, C2c, C2d) of a photodetector according to one or more embodiments of this application. The photodetector may include a structure substantially the same as any of the above embodiments, such as 100a, 100c, 100d, 200a, 200d, 200e, 200g, 200h, 200i, 300a, 400a, 400c, or 400e.

[0106] In some embodiments, as shown in FIG6A, the control electrode 340 may be on the first surface 21 of the substrate 20 and have an intrinsic region below it. Depending on factors such as the material of the substrate 20, the material of a passivation layer on the first surface 21, and / or the material of the control electrode 340, and / or the degree of doping or defects in the substrate 20 or the passivation layer, the control electrode 340 may form a Schottky contact, an ohmic contact, or a combination of intermediate characteristics between the two. The control electrode 340 may be any of control electrodes 340a, 340b, 340c, 340d, 360a, 360b, 360c, and 360d.

[0107] As shown in Figure 6B, in some embodiments, the control region of the switch further includes a carrier control region 303 (e.g., 304a, 304b, or 306a) below the control electrode 340 and in the substrate 20. In some embodiments, the carrier control region 303 has a different conduction type than the carrier acquisition regions 302a and 302b. In some embodiments, the carrier control region 303 includes a dopant and a doping distribution. The peak doping concentration of the carrier control region 303 depends on the material of the control electrode 340, and / or the material of the substrate 20, and / or the degree of doping or defects in the substrate 20, for example, between 1 x 10¹⁷ cm⁻³ and 5 x 10²⁰ cm⁻³. The carrier control region 303 may form a Schottky contact, an ohmic contact, or a combination thereof with the control electrode 340. The carrier control region 303 is used to demodulate the carriers generated in the absorption region 10 according to the control signal. The control electrode 340 can be any one of the control electrodes 340a, 340b, 340c, 340d, 360a, 360b, 360c, and 360d.

[0108] As shown in Figure 6C, in some embodiments, the control region of the switch is further included in a dielectric layer 342 between the substrate 20 and the control electrode 340. The dielectric layer 342 prevents direct current conduction from the control electrode 340 to the substrate 20, but allows an electric field to be generated in the substrate 20 in response to a voltage applied to the control electrode 340. The electric field generated in the two control regions (e.g., in control regions C1, C2) can attract or repel charge carriers in the substrate 20. The control electrode 340 can be any of control electrodes 340a, 340b, 340c, 340d, 360a, 360b, 360c, and 360d.

[0109] As shown in Figure 6D, in some embodiments, the control region of the switch is contained within a carrier control region 303 below the control electrode 340 and within the substrate 20, and is also contained within a dielectric layer 342 between the substrate 20 and the control electrode 340. The control electrode 340 may be any one of control electrodes 340a, 340b, 340c, 340d, 360a, 360b, 360c, and 360d.

[0110] In some embodiments, dielectric layer 342 may comprise, but is not limited to, silicon dioxide (SiO2). In some embodiments, dielectric layer 342 may comprise high dielectric constant materials including, but not limited to, silicon nitride (Si3N4), silicon oxynitride (SiON), silicon nitride (SiNx), silicon oxide (SiOx), germanium oxide (GeOx), aluminum oxide (Al2O3), yttrium oxide (Y2O3), titanium dioxide (TiO2), hafnium dioxide (HfO2), or zirconium dioxide (ZrO2). In some embodiments, dielectric layer 342 may comprise semiconductor materials, but is not limited to, amorphous silicon, polycrystalline silicon, crystalline silicon, germanium silicide, or combinations thereof.

[0111] Figure 7A is a block diagram of one embodiment of an imaging system 700. The imaging system 700 may include a sensing module 710 and a software module 720, the software module 720 being configured to reconstruct a 3D model 730 of a detected object. The imaging system 700 or the sensing module 710 may be implemented in a mobile device (e.g., a smartphone, a tablet, a car, a drone, etc.), used as an auxiliary device of a mobile device (e.g., a wearable device), in a computing system in a car or in a fixed facility (e.g., a factory), a robotic system, a monitoring system, or any suitable device and / or system.

[0112] The sensing module 710 includes a transmitter unit 714, a receiver unit 716, and a controller 712. In operation, the transmitter unit 714 emits a emitted light 703 toward a target object 702. The receiver unit 716 receives reflected light 705 reflected from the target object 702. The controller 712 can drive at least the transmitter unit 714 and the receiver unit 716. In some embodiments, the receiver unit 716 and the controller 712 are implemented on a single semiconductor chip, such as a system-on-a-chip (SoC). In some embodiments, the transmitter unit 714 is implemented on two different semiconductor chips, such as a laser emitter chip on a III-V substrate and a silicon laser driver chip on a silicon substrate.

[0113] The emitter unit 714 may include one or more light sources, control circuitry for controlling one or more light sources, and / or optical structures for manipulating light emitted from one or more light sources. In some embodiments, the light source may include one or more light-emitting diodes (LEDs) or vertical cavity surface-emitting lasers (VCSELs), whose emitted light can be absorbed by an absorption region in a photodetector. For example, one or more LEDs or VCSELs may emit light with a peak wavelength in the visible light range (e.g., a wavelength visible to the human eye), such as 570 nm, 670 nm, or any other suitable wavelength. Alternatively, one or more LEDs or VCSELs may emit light with a peak wavelength above the visible light range, such as 850 nm, 940 nm, 1050 nm, 1064 nm, 1310 nm, 1350 nm, 1550 nm, or any other suitable wavelength.

[0114] In some implementations, the emitted light from the light source can be aligned by one or more optical structures. For example, the optical structure may include one or more alignment lenses.

[0115] Receiver unit 716 may include one or more photodetectors according to any of the embodiments described above, such as 100a, 100c, 100d, 200a, 200d, 200e, 200g, 200h, 200i, 300a, 400c, or 400e. Receiver unit 716 may further include control circuitry for controlling the circuitry and / or optical structure to direct light reflected from the target object toward one or more photodetectors. In some embodiments, the optical structure includes one or more lenses that receive an alignment light and focus the alignment light toward one or more photodetectors.

[0116] In some embodiments, the controller 712 includes a timing generator (e.g., 772 shown in FIG. 7B) and a processing unit. The timing generator 772 receives a reference clock signal and provides a timing signal to the transmitter unit 714 to modulate the emitted light 703. The timing signal is also provided to the receiver unit 716 to control the collection of photocarriers. The processing unit processes the photocarriers generated and collected by the receiver unit 716 and determines the raw data of the target object 702. The processing unit may include control circuitry for processing information output from the photodetector, one or more signal processors 758, and / or computer storage media, which may store instructions for determining the raw data of the target object 702 or store the raw data of the target object 702. As an example, in an indirect time-of-flight (i-ToF) sensor, the controller 712 determines the distance between two points by using the phase difference between the light emitted by the transmitter unit 714 and the light received by the receiver unit 716.

[0117] The software module 720 can be implemented to perform applications such as facial recognition, eye tracking, gesture recognition, 3D module scanning / video recording, motion tracking, self-driving cars, and / or augmented / virtual reality.

[0118] Figure 7B shows a block diagram of an exemplary device 750, which may be a receiver unit (e.g., 716) or a controller (e.g., 712). Here, an image sensor array 752 (e.g., a 240 x 180 pixel array) may be implemented using any of the aforementioned embodiments of the light detection device (e.g., 100a, 100c, 100d, 200a, 200d, 200e, 200g, 200h, 200i, 300a, 400c, or 400e). A phase-locked loop (PLL) circuit 770 (e.g., an integer-N PLL) can generate a clock signal (e.g., a four-phase system clock) for modulation and demodulation. Before being sent to the image sensor array 752 and the external illumination driver 780, these clock signals can be gated and / or modulated by a timing generator 772 to a preset integration time and different operating modes. A programmable delay line 768 can be added to the illumination driver 780 path to delay the clock signal.

[0119] A voltage regulator 762 may be used to control the operating voltage of one of the image sensor arrays 752. For example, an N-voltage domain may be used in an image sensor. A temperature sensor 764 may be implemented to utilize depth calibration and power control, and an integrated circuit (IC) controller 766 may obtain temperature information from the temperature sensor 764.

[0120] The readout circuit 754 of the detection device bridges each photodetector of the image sensor array 752 to a row of analog-to-digital converters (ADCs) 756, wherein the output of the ADC 756 can be further processed and integrated in the digital domain by a signal processor 758 before reaching the output interface 774. The output interface 774 is coupled to a timing generator 772. In some embodiments, the readout circuit 754 may be a tri-transistor configuration having a reset gate, a source follower, and a selection gate, or a quad-transistor configuration, often including a transmission gate, or any suitable circuitry capable of processing the charge collected in each readout region.

[0121] A memory 760 may be used to store the output of the signal processor 758. In some embodiments, the output interface 774 may utilize a 2-lane, 1.2 Gb / s D-PHY mobile industry processor interface (MIPI) transmitter, or for low-speed / low-cost systems, a CMOS output may be used. Digital data further modulated by the signal processor 758 is transmitted via the MIPI interface 776 for further processing.

[0122] An integrated circuit bus (I2C) interface can be used to access all the functional blocks described herein.

[0123] In some embodiments, the bandgap of the substrate 20 is larger than the bandgap of the absorption region 10. In some embodiments, the absorption region 10 comprises or is composed of a semiconductor material. In some embodiments, the substrate 20 comprises or is composed of a semiconductor material. In some embodiments, the absorption region 10 comprises or is composed of a group III-V semiconductor material. In some embodiments, the substrate 20 comprises or is composed of a group III-V semiconductor material. The group III-V semiconductor material may include, but is not limited to, gallium arsenide / aluminum arsenide (GaAs / AlAs), indium phosphide / indium gallium arsenide (InP / InGaAs), gallium antimonide / indium arsenide (GaSb / InAs), or indium antimonide (InSb). For example, in some embodiments, the absorption region 10 comprises or is composed of InGaAs, and the substrate 20 comprises or is composed of InP. In some embodiments, the absorption region 10 comprises or is composed of a semiconductor material containing a group IV element. For example, germanium (Ge), silicon (Si), or tin (Sn). In some embodiments, the absorption region 10 comprises or is composed of Si xGe ySn 1-xy, where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1. In some embodiments, the absorption region 10 comprises or is composed of Ge 1-aSn a, where 0 ≦ a ≦ 0.1. In some embodiments, the absorption region 10 comprises or is composed of Ge xSi 1-x, where 0 ≦ x ≦ 1. In some embodiments, the absorption region 10 is composed of p-type intrinsic germanium, the p-type being due to material defects formed during the formation of the absorption region, wherein the defect density is from 1 x 10¹⁴ cm⁻³ to 1 x 10¹⁶ cm⁻³. In some embodiments, the carrier guiding regions 201, 201a, 201b, 201c, 201d comprise or are composed of semiconductor materials containing group IV elements. For example, germanium (Ge), silicon (Si), or tin (Sn). In some embodiments, the substrate 20 comprises or is composed of Si xGe ySn 1-xy, where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1. In some embodiments, the substrate 20 comprises or is composed of Ge 1-aSn a, where 0 ≦ a ≦ 0.1. In some embodiments, the substrate 20 comprises or is composed of Ge xSi 1-x, where 0 ≦ x ≦ 1. For example, in some embodiments, the absorption region 10 is composed of germanium, and the substrate 20 comprises or is composed of silicon.

[0124] In some embodiments, the photodetector disclosed herein further includes an optical element (not shown) on a pixel. In some embodiments, the photodetector disclosed herein further includes N optical elements (not shown) on N pixels. The optical elements converge an incoming light signal to direct it into a light-absorbing area. In some embodiments, the optical elements include a plurality of lenses.

[0125] 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.

[0126] In this disclosure, unless otherwise specified, the absorption region is configured to absorb photons having a peak wavelength in an invisible wavelength range equal to or greater than 800 nm (e.g., 850 nm, 940 nm, 1050 nm, 1064 nm, 1310 nm, 1350 nm, or 1550 nm, or any suitable wavelength range). In some embodiments, the absorption region receives an optical signal and converts the optical signal into an electrical signal. The absorption region can be of any suitable shape, such as, but not limited to, cylindrical or rectangular prism.

[0127] In this disclosure, unless otherwise specified, the absorption region has a thickness that depends on the wavelength of the photon to be detected and the material of the absorption region. In some embodiments, when the absorption region comprises germanium and is designed to absorb photons with a wavelength equal to or greater than 800 nm, the absorption region has a thickness equal to or greater than 0.1 μm. In some embodiments, the absorption region comprises germanium and is designed to absorb photons with a wavelength between 800 nm and 2000 nm, and 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 to achieve higher quantum efficiency. In some embodiments, the absorption region may be grown using a blanket epitaxy, a selective epitaxy, or other suitable techniques.

[0128] In this disclosure, unless otherwise specified, the light mask has an optical window for defining the position of the light signal receiving area within the absorption region. In other words, the optical window is used to allow incident optical signals to enter the absorption region and to define the light signal receiving area. In some embodiments, when incident light enters the absorption region from a second surface of the substrate remote from the absorption region, the light mask is situated on the second surface of the substrate. In some embodiments, as shown in a top view, the shape of the optical window may be elliptical, circular, rectangular, square, rhomboid, octagonal, or any other suitable shape.

[0129] In this disclosure, unless otherwise specified, in the same primitive, the type of photocarriers collected by the carrier acquisition region of one of the multiple switches is the same as the type of photocarriers collected by the carrier acquisition region of the other multiple switches. 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 carrier acquisition region of the first switch collects electrons of photocarriers generated by the absorption region, and when the second switch is turned on and the first switch is turned off, the carrier acquisition region of the second switch also collects electrons of photocarriers generated by the absorption region.

[0130] In this disclosure, unless otherwise specified, the term "electrode" includes metals or alloys. For example, the first electrode, the second electrode, the readout electrode, and the control electrode include aluminum, copper, tungsten, titanium, tantalum-tantalum nitride-copper stack, or titanium-titanium nitride-tungsten stack.

[0131] In some embodiments, unless otherwise specified, the cross-sectional view shown in this disclosure may be a cross-sectional view along any possible cross-sectional line of a light detection device.

[0132] Unless otherwise defined, the terms "substantially" and "approximately" are used to describe and narrate small changes. When combined with an event or situation, the term may include the exact moment the event or situation occurred, or an approximate point in time. For example, when combined with a numerical value, the term may include a range of variation less than or equal to ±10% of the value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%.

[0133] While the above description is based on preferred embodiments, it should be understood that these preferred embodiments do not constitute a limitation on this application. Rather, this application should cover various modifications and similar arrangements and processes, and therefore the scope of the appended claims should be interpreted in the broadest sense to encompass all modifications and similar arrangements and processes.

[0134] 10: Absorption Region 100a: Light detection device 100c: Light detection device 100d: Light Detection Device 102a: First group of switches / switch 102b: Second group of switches / switch 102c: Third group of switches / switch 102d: Fourth group of switches / switch 104a: Carrier Output Region 104b: Carrier Output Region 105a: Gain Component 105b: Gain Component 108: First Contact Zone 101: Layers 102: Layers 103: Layers 11: First Surface 110: Control Unit 112: Readout Circuit 112a: First readout circuit 112b: Second readout circuit 12: Second Surface 13: Side surface 20: Base 200a: Light Detection Device 200d: Light Detection Device 200e: Light Detection Device 200g: Light detection device 200h: Light detection device 200i: Light Detection Device 201: Carrier Guidance Region 201a: Carrier Guidance Region 201b: Carrier Guidance Region 201c: Carrier Guidance Region 201d: Carrier Guidance Region 202a: Second contact area 202b: Second Contact Zone 203a: Third contact area 203b: Third Contact Zone 21: First Surface 22: Second Surface 300a: Light Detection Device 302a: Carrier Acquisition Area 302b: Carrier Acquisition Area 303: Carrier Control Region 304a: Carrier Control Region 304b: Carrier Control Region 305a: Carrier Acquisition Area 305b: Carrier Acquisition Area 306a: Carrier Control Region 330a: Readout electrode 330b: Readout electrode 330c: Readout Electrode 330d: Readout electrode 370a: Readout electrode 370b: Readout Electrode 370c: Readout Electrode 370d: Readout electrode 350a: Anti-doped region 350b: Anti-doped region 380a: Anti-doped region 380b: Anti-doped region 340: Control electrode 340a: Control electrode 340b: Control electrode 340c: Control electrode 340d: Control electrode 360a: Control electrode 360b: Control electrode 360c: Control electrode 360d: Control Electrode 342: Dielectric layer 400a: Light Detection Device 400c: Light Detection Device 400e: Light Detection Device 500a: Structure 500b: Structure 500c: Structure 60: First electrode 700: Imaging System 702: Target object 703: Emitting light 705: Reflected light 710: Sensor Module 712: Controller 714: Transmitter Unit 716: Receiver Unit 720: Software Module 730: 3D Model 750: Equipment 752: Image Sensor Array 754: Readout Circuit 756: Analog-to-Digital Converter (ADC) 758: Signal Processor 760: Memory 762: Voltage Regulator 764: Temperature Sensor 766: Integrated Circuit (IC) Controller 768: Programmable Delay Line 770: Phase-locked loop circuit 772: Timing Generator 774: Output Interface 776: MIPI Interface 780: Lighting Driver A: Peak doping concentration B: Peak doping concentration C: Peak doping concentration AR: Optical signal receiving area C1: Control Area C1a: Control Area C1b: Control Area C1c: Control Area C1d: Control Area C2: Control Area C2a: Control Area C2b: Control Area C2c: Control Area C2d: Control Area Ma: Doubling Zone Mb: Doubling Zone R1a: Readout area R1b: Readout area R1c: Readout area R1d: Readout area R2a: Second readout area R2b: Second readout area R2c: Second readout zone R2d: Second readout area S1a: First switch S1b: First switch S1c: First switch S1d: First switch S2a: Second switch S2b: Second switch S2c: Second switch S2d: Second switch

Claims

1. A photodetector comprising: a substrate including a first material; an absorption region including a second material, wherein the absorption region is supported by the substrate and wherein the absorption region is configured to receive an optical signal and generate photocarriers in response to the optical signal; and a plurality of switches, including a first set and a second set, wherein... The absorption region is disposed between the first group and the second group. The first group includes a first control region and a second control region, as well as a first readout region and a second readout region. The second group includes a third control region and a fourth control region, as well as a third readout region and a fourth readout region. The first control region and the third control region are coupled to a first control signal, and the second control region and the fourth control region are coupled to a second control signal. The first readout region and the third readout region are coupled to a first readout circuit, and the second readout region and the fourth readout region are coupled to a second readout circuit.

2. The photodetector as claimed in claim 1, further comprising one or more carrier guiding regions at least partially formed within the substrate and in contact with the absorption region, wherein, Each of the one or more carrier guidance regions is electrically coupled to a corresponding group switch in the plurality of groups of switches.

3. The light detection device as described in claim 2, wherein, Each of the one or more carrier guiding regions is n-type doped.

4. The light detection device as described in claim 2, wherein, The absorption region also includes a plurality of carrier output regions, each of which individually contacts a corresponding carrier guiding region in one or more carrier guiding regions.

5. The light detection device as described in claim 2, wherein: The absorption region belongs to a first conduction type, the one or more carrier guiding regions belong to a second conduction type different from the first conduction type, the substrate belongs to the first conduction type, each of the control regions in each group includes a carrier control region belonging to the first conduction type, each of the readout regions in each group includes a carrier acquisition region belonging to the second conduction type, and the one or more carrier guiding regions are separate from the carrier control regions of the control region and the carrier acquisition regions of the readout region.

6. The light detection device as described in claim 5, wherein, The substrate further includes an anti-doped region that at least partially overlaps with one of the carrier control regions, wherein the anti-doped region belongs to the second conduction type.

7. The light detection device as described in claim 1, wherein, The absorption region is doped with a gradient doping distribution.

8. The light detection device as described in claim 7, wherein, The absorption region includes a first surface and a second surface, wherein the second surface is located between the first surface of the absorption region and a surface of the substrate, and wherein the gradient doping distribution of the absorption region gradually decreases along the direction from the second surface of the absorption region to the first surface of the absorption region.

9. The light detection device as described in claim 1, wherein, The absorption region is at least partially embedded in the substrate.

10. The light detection device as described in claim 1, wherein, The multiple sets of switches further include a third set and a fourth set, wherein the absorption region is disposed between the third set and the fourth set. The third set includes a fifth control region and a sixth control region, as well as a fifth readout region and a sixth readout region. The fourth set includes a seventh control region and an eighth control region, as well as a seventh readout region and an eighth readout region. The fifth control region and the seventh control region are coupled to the first control signal, and the sixth control region and the eighth control region are coupled to the second control signal. The fifth readout region and the seventh readout region are coupled to the first readout circuit, and the sixth readout region and the eighth readout region are coupled to the second readout circuit.

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