Photo-detecting apparatus and imaging system thereof

Abstract

This application provides an apparatus and imaging system for photosensing. In one embodiment, a photosensing apparatus includes: a pixel whose absorption region is configured to receive an optical signal and generate photocarriers in response to the optical signal; a substrate supporting the absorption region; and at least one additional region formed in the substrate. The absorption region includes a first material, the substrate includes a second material different from the first material, and the at least one additional region includes a third material different from the second material. The total area of ​​the absorption region and the at least one additional region is at least 20% of the pixel area.

Description

[Technical Field]

[0001] This application relates primarily to a detector. Specifically, this application provides a light detection device and its imaging system. [Previous Technology]

[0002] A photodetector can be used to detect optical signals and convert them into electrical signals that can be processed by other circuit systems. Photodetectors 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, components, apparatus, methods and techniques for optical detection.

[0005] One embodiment of this application provides a photodetector including a pixel, wherein an absorption region of the pixel is configured to receive an optical signal and generate photocarriers in response to the optical signal, wherein the absorption region includes a first material. The photodetector also includes a substrate supporting the absorption region, the substrate including a second material different from the first material. The photodetector also includes an additional region formed in the substrate, the additional region including a third material different from the second material. The total area of ​​the absorption region and the additional region is at least 20% of the pixel area.

[0006] One embodiment of this application provides a photodetector, including a pixel, wherein an absorption region of the pixel is configured to receive an optical signal and generate photocarriers in response to the optical signal, wherein the absorption region includes a first material. The photodetector further includes a substrate supporting the absorption region, the substrate including a second material different from the first material. The photodetector further includes an additional region formed in the substrate, the additional region including a third material different from the second material. The photodetector further includes a light shield including an optical window corresponding to the absorption region. The light shield blocks the optical signal from entering the additional region.

[0007] In some embodiments, the photodetector further includes an isolation region formed in the substrate.

[0008] In some embodiments, the isolation region surrounds the absorption region and is located between the absorption region and the additional region.

[0009] In some embodiments, the isolation region surrounds the absorption region and the additional region.

[0010] In some embodiments, the first material is the same as the third material.

[0011] In some embodiments, the third material includes a metal.

[0012] In some embodiments, the third material includes an insulating material.

[0013] In some embodiments, each pixel includes two switches electrically coupled to the corresponding absorption region.

[0014] In some embodiments, the absorption region is doped with a first dopant belonging to a first conduction type.

[0015] In some embodiments, the additional region is doped with a first conduction type.

[0016] In some embodiments, the photodetector further includes a blocking layer surrounding the additional region.

[0017] In some embodiments, the photodetector further includes a low barrier region that is in contact with the absorption region and separate from the additional region.

[0018] In some embodiments, the photodetector further includes a plurality of switches electrically coupled to the absorption region. Each of the plurality of switches includes a readout electrode. The plurality of readout electrodes are located on the same side of the absorption region.

[0019] One embodiment of this application provides a photodetector including a pixel, wherein an absorption region of the pixel is configured to receive an optical signal and generate photocarriers in response to the optical signal, wherein the absorption region includes a first material. The photodetector also includes a substrate supporting the absorption region, the substrate including a second material different from the first material. The photodetector also includes an additional region formed in the substrate, the additional region including a third material different from the second material. The photodetector also includes a low barrier region formed in the substrate, which is in contact with the absorption region and separated from the additional region.

[0020] In some embodiments, the absorption region is doped with a first dopant belonging to a first conduction type. The low barrier region is doped with another dopant belonging to a second conduction type. The first conduction type is different from the second conduction type.

[0021] Another embodiment of this application is a photodetector, including two adjacent pixels, each having an absorption region configured to receive an optical signal and generate photocarriers in response to the optical signal, wherein the absorption region includes a first material. The photodetector also includes a substrate supporting the two adjacent pixels, the substrate including a second material different from the first material. The photodetector also includes an additional region of one bit between the absorption regions of the two adjacent pixels, the additional region including a third material different from the second material. The photodetector also includes two isolation regions, each surrounding a corresponding absorption region in the absorption regions of the two adjacent pixels.

[0022] In some embodiments, in each of two adjacent pixels, the total area of ​​the absorption region and the additional region is at least 20% of the pixel area.

[0023] In some embodiments, the first material is the same as the third material.

[0024] In some embodiments, the third material includes metal.

[0025] In some embodiments, the third material includes an insulating material.

[0026] In some embodiments, an isolation region surrounds an additional region and a corresponding absorption region.

[0027] Another embodiment of this application is an imaging system, comprising: a transmitter; a receiver; a signal processor electrically communicating with the receiver; and a controller electrically communicating with the signal processor and the transmitter. The receiver includes one or more photodetectors. Each of the one or more photodetectors includes: a pixel including an absorption region configured to receive an optical signal and generate photocarriers in response to the optical signal; a substrate supporting the absorption region; and an additional region formed in the substrate. The absorption region includes a first material, the substrate includes a second material different from the first material, and the additional region includes a third material different from the second material. The total area of ​​the absorption region and the additional region is at least 20% of the area of ​​a pixel.

[0028] In some embodiments, the imaging system further includes an isolation region formed in the substrate. The isolation region may surround the absorption region and may be located between the absorption region and the additional region.

[0029] In some embodiments, the isolation region surrounds the absorption region and the additional region.

[0030] In some embodiments, the first material is the same as the third material.

[0031] In some embodiments, the absorption region is doped with a first dopant belonging to a first conduction type.

[0032] In some embodiments, the additional region is doped with a first conduction type.

[0033] Another embodiment of this application is a photodetector, comprising: a substrate including a first material; an absorption region supported by the substrate and configured to receive an optical signal and generate photocarriers in response to the optical signal; a density compensation region supported by the substrate and separated from the absorption region; and a first electrode formed on a first surface of the density compensation region and electrically coupled to the density compensation region and the absorption region to collect a first portion of the photocarriers generated by the absorption region. The absorption region includes a second material different from the first material, and the absorption region is doped with a first dopant belonging to a first conduction type. The density compensation region includes a second material, and the density compensation region is doped with a second dopant belonging to a second conduction type opposite to the first conduction type.

[0034] In some embodiments, the photodetector further includes: a second electrode formed on the first surface of the substrate or the first surface of the absorption region, and electrically coupled to the absorption region. The second electrode is configured to collect a second portion of photocarriers generated by the absorption region. In some embodiments, the first portion and the second portion of the photocarriers have different polarities.

[0035] In some embodiments, the absorption region has a first peak doping concentration, the substrate includes a low barrier region, and the low barrier region of the substrate or the substrate in contact with the absorption region is doped with a third dopant belonging to a second conduction type and having a second peak doping concentration. In some embodiments, the ratio between the first peak doping concentration of the absorption region and the second peak doping concentration of the substrate or the low barrier region is equal to or greater than 10. In some embodiments, at least a portion of the low barrier region is disposed between the absorption region and the density compensation region. In some embodiments, the third peak doping concentration of the density compensation region is higher than the second peak doping concentration of the substrate or the low barrier region.

[0036] In some embodiments, at least a portion of the absorption region or at least a portion of the density compensation region is embedded in the substrate.

[0037] In some embodiments, the substrate is made of silicon, the absorption region is made of germanium, and the density compensation region is made of germanium.

[0038] In some embodiments, the substrate further includes a high barrier region of the contact absorption region, and the high barrier region is doped with a fourth dopant belonging to the first conduction type.

[0039] Another aspect of this application provides a photodetector, comprising: a substrate including a first material; an absorption region supported by the substrate and configured to receive an optical signal and generate photocarriers in response to the optical signal; one or more density compensation regions supported by the substrate and separated from the absorption region; and one or more switches electrically coupled to the absorption region and partially formed in the substrate. The absorption region includes a second material different from the first material, and the absorption region is doped with a first dopant belonging to a first conduction type. The one or more density compensation regions include a second material, and the one or more density compensation regions are doped with a second dopant belonging to a second conduction type opposite to the first conduction type. Each of the one or more switches includes a control electrode and a readout electrode, wherein each readout electrode is formed on a first surface of a corresponding density compensation region in the one or more density compensation regions, and each readout electrode is configured to collect a first portion of the photocarriers generated by the absorption region.

[0040] In some embodiments, one or more control electrodes are each formed above a first surface of the substrate and separated from the absorption region.

[0041] In some embodiments, the absorption region has a first peak doping concentration, the substrate includes one or more low barrier regions, and the substrate or one or more low barrier regions in contact with the absorption region are doped with a third dopant belonging to a second conduction type and having a second peak doping concentration. In some embodiments, the ratio between the first peak doping concentration of the absorption region and the second peak doping concentration of the substrate or one or more low barrier regions is equal to or greater than 10. In some embodiments, at least a portion of the one or more low barrier regions is disposed between the absorption region and one or more density compensation regions. In some embodiments, the third peak doping concentration of the one or more density compensation regions is higher than the second peak doping concentration of the substrate or one or more low barrier regions.

[0042] In some embodiments, at least a portion of the absorption region or at least a portion of one or more density compensation regions are embedded in the substrate.

[0043] In some embodiments, the substrate is made of silicon, the absorption region is made of germanium, and one or more density compensation regions are made of germanium.

[0044] In some embodiments, the substrate further includes a high barrier region of the contact absorption region, and the high barrier region is doped with a fourth dopant belonging to the first conduction type.

[0045] In some embodiments, one or more readout electrodes and one or more control electrodes are disposed on the same side of the absorption region.

[0046] Another embodiment of this application is an imaging system, comprising: a transmitter; a receiver; a signal processor electrically communicating with the receiver; and a controller electrically communicating with the signal processor and the transmitter. The receiver includes any or more of the photodetectors described in this application.

[0047] 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.

Implementation Method

[0049] FIG1A depicts a top view of an exemplary light detection device 100 according to one or more embodiments of the present application. FIG1B depicts a cross-sectional view of the light detection device 100 in FIG1A along line A-A' according to one or more embodiments of the present application.

[0050] As shown in FIG1B, the photodetector 100 includes one or more pixels 180, each pixel 180 having an absorption region 110. The photodetector 100 also includes a substrate 120 providing support for the absorption region 110. In some embodiments, the substrate 120 includes one or more trenches or recesses, wherein at least a portion of the absorption region 110 is formed in the trenches or recesses. In some embodiments, an output electrical signal is determined by photocarriers generated by the absorption region 110. The absorption region 110 is configured to receive an optical signal and generate photocarriers in response to the optical signal. The substrate 120 includes a first material (e.g., silicon), and the absorption region 110 includes a second material (e.g., germanium) different from the first material. In some embodiments, the absorption region 110 is doped with a first dopant (e.g., boron) belonging to a first conduction type (e.g., p-type). In some embodiments, the substrate 120 is made of silicon, and the absorption region 110 is made of germanium.

[0051] In some embodiments, one or more pixels 180 each include one or more additional regions 150, which are supported by the substrate 120 and separated from the absorption region 110. In some embodiments, at least a portion of the one or more additional regions 150 are formed in one or more trenches or recesses of the substrate 120. For example, as shown in FIG1A, the photodetector 100 includes four additional regions 150 arranged on the four sides of the absorption region 110. The shape, size, and position of the additional regions 150 are not limited to the examples shown in the figures. For example, the additional regions 150 may be annular around the absorption region 110. The number of additional regions may be 2N, where N is a positive integer, for example, but not limited to 1 or 2.

[0052] In some embodiments, the total area of ​​the absorption region 110 and the additional region 150 is at least 20% (e.g., 25% to 40%) of the area of ​​the pixel 180. In some embodiments, the distance between two adjacent pixels 180 is measured between two adjacent absorption regions 110. In some embodiments, the distance between two adjacent pixels 180 is measured between the centers of two adjacent absorption regions 110.

[0053] In some embodiments, the depth of the additional region 150 may be the same as or different from that of the absorption region 110.

[0054] In some embodiments, the additional region 150 includes a third material different from the first material of the substrate 120, such as SiOx, SiOxNy, or InGaAsP. In some examples, the third material includes a metal, such as Al or Cu, so that the additional region 150 can confine scattered light within the photodetector 100. In some examples, the third material includes an insulating material. In some examples, the third material is the same as the second material, such as pure germanium or SixGe1-x. In some embodiments, the additional region 150 may include a composite layer, such as, but not limited to, two or three layers with different materials. For example, the additional region 150 may have a layer of SiO2 deposited, followed by an adhesive layer of TiNx, and then the remainder of the trench filled with metal.

[0055] In some embodiments, the additional region 150 may also absorb scattered light, and photocarriers not collected by the electrode (e.g., the first electrode 130) may recombine within the additional region 150, rather than generating electrical noise as in the substrate without the additional region 150. For example, if the second material of the substrate 320 is Si, the second material may not be able to absorb long-wavelength light, such as, but not limited to, light with a peak wavelength greater than 800 nm. Therefore, if the third material of the additional region 350 is different from the second material, such as germanium, the additional region 150 may absorb scattered light and can be used to reduce optical crosstalk. In some embodiments, a doped region may be added within the additional region 150 or an electrode may be added to the additional region 150. In some embodiments, the additional region 150 may include a photodiode or be used for correction purposes.

[0056] In some embodiments, at least one additional region 150 is a density compensation region, for example, used to increase the material density of a material different from that of the substrate 120 in the same pixel, thereby improving the quality of the absorption region 110. That is, the additional region 150 can achieve a more ideal distribution of material formed in or on the trenches or recesses of the substrate and different from that of the substrate (e.g., more uniform pattern density, higher overall density, center / edge compensation, etc.), thereby improving the device yield on the entire wafer. In some embodiments, when the third material is the same as the second material, the additional region 150 can achieve a more ideal distribution of light-absorbing material on the substrate (e.g., more uniform pattern density, higher overall density, center / edge compensation, etc.), thereby improving the device yield on the entire wafer.

[0057] The additional region 150 can improve the growth quality of the absorption region 110, thereby improving pixel performance and process yield. In some embodiments, the additional region 150 may be an isolation structure used to reduce or prevent signal crosstalk between adjacent pixels 180.

[0058] In some embodiments, the absorption region 110 includes a light signal receiving region AR, defined by a light shield (not shown) having an optical window. The light signal receiving region (AR) can receive optical signals entering from the optical window. In some embodiments, optical signals incident from the light shield side are blocked by the light shield and cannot enter the additional region 150 in a predetermined manner.

[0059] In some embodiments, the photodetector 100 includes a first doped region 104 formed in the substrate 120 and separated from the absorption region 110. In some embodiments, the first doped region 104 is separated from the additional region 150. The first doped region 104 may be doped with a second dopant (e.g., phosphorus) belonging to a second conductivity type (e.g., n-type), which is the opposite of the first conductivity type (e.g., p-type).

[0060] In some embodiments, the absorption region 110 is doped with a first dopant belonging to a first conduction type (e.g., p-type) and having a first peak doping concentration. In some embodiments, at least a portion of the substrate 120, such as the low barrier region 106 which will be detailed below, or the entire substrate 120, is substantially doped with a third dopant (e.g., phosphorus) belonging to a second conduction type (e.g., n-type) and having a second peak doping concentration. The ratio of the first peak doping concentration to the second peak doping concentration may be equal to or greater than a threshold ratio (e.g., 10) capable of reducing the dark current of the photodetector 100. In some embodiments, the range of the first peak doping concentration is 1 x 10¹⁶ cm⁻³ to 1 x 10²⁰ cm⁻³. The range of the second peak doping concentration is 1 x 10¹⁵ cm⁻³ to 1 x 10¹⁷ cm⁻³.

[0061] In some embodiments, the additional region 150 may be doped with a dopant of the first conduction type (e.g., p-type) in the same way as the absorption region 110. In some embodiments, the peak doping concentration of the dopant in the additional region 150 is in the range of 1 x 10¹⁶ cm⁻³ to 1 x 10¹⁹ cm⁻³, which can increase the recombination rate of carriers in the additional region 150, thereby reducing the dark current of the photodetector 100.

[0062] The photodetector 100 may further include a first electrode 130, which is formed above the first doped region 104 and electrically coupled to the first doped region 104 and the absorption region 110, for collecting a first portion (e.g., electrons) of a first type of photocarrier generated by the absorption region 110.

[0063] In some embodiments, the photodetector 100 includes a second doped region 108 formed in the absorption region 110 and adjacent to the first surface 111 of the absorption region 110. The second doped region 108 may be doped with a first conduction type (e.g., p-type). In some embodiments, the second doped region 108 is doped with a dopant (e.g., boron) whose peak doping concentration is higher than the first peak doping concentration of the absorption region 110.

[0064] In some embodiments, the photodetector 100 further includes a second electrode 160 which may be formed above the second doped region 108 and electrically coupled to the absorption region 110. The second electrode 160 is configured to collect a second portion (e.g., a hole) of photocarriers generated by the absorption region 110.

[0065] In some embodiments, the first portion of photocarriers collected by the first electrode 130, such as electrons, is different from the second portion of photocarriers collected by the second electrode 160, such as holes. The collected photocarriers can be processed by different circuit systems, such as readout circuit systems (e.g., readout circuit 1054 of FIG. 10B).

[0066] In some embodiments, the photodetector 100 includes a low barrier region 106 formed in a substrate 120. The low barrier region 106 may be in contact with the absorption region 110. In some embodiments, at least a portion of the low barrier region 106 is located between the absorption region 110 and the first doped region 104. In some embodiments, the low barrier region 106 is separated from the additional region 150. In some embodiments, the low barrier region 106 is doped with a third dopant (e.g., phosphorus) of a second conduction type (e.g., n-type) and having a second peak doping concentration. The low barrier region 106 may be configured to guide a first portion (e.g., electrons) of photocarriers generated by the absorption region 110 to move in a confined region, such that the first portion (e.g., electrons) of photocarriers can flow from the absorption region 110 through the low barrier region 106 to the first doped region 104, and then be collected by the first electrode 130.

[0067] In some embodiments, the first doped region 104 is doped with a second dopant belonging to a second conduction type (e.g., n-type) and having a third peak doping concentration. The third peak doping concentration may be higher than the second peak doping concentration to attract a first portion of photocarriers (e.g., electrons) to the first doped region 104 and then collect them by the first electrode 130.

[0068] In some embodiments, as shown in FIG1A and 1B, the photodetector 100 includes one or more isolation regions 102 formed in the substrate 120. In some embodiments, the isolation region 102 may be formed via implantation. In some embodiments, the isolation region 102 may be a doped region. In some embodiments, the isolation region 102 belongs to a second conduction type, such as n-type.

[0069] In some embodiments, the isolation region 102 includes a semiconductor material different from the second material of the substrate 120. The interface between the two semiconductor materials formed between the substrate 120 and the isolation region 102 can create an energy barrier due to bandgap shift, preventing current from passing through the isolation region 102 and improving electrical insulation between adjacent pixels 180. In some embodiments, the isolation region 102 may be annular or square surrounding the absorption region 110. In some embodiments, the isolation region 102 may include two separate regions disposed on opposite sides of the absorption region 110.

[0070] In some embodiments, the isolation region 102 is a trench filled with a dielectric material or an insulating material, forming a high-resistance region between two adjacent pixels 180, preventing current from passing through the isolation region 102 and improving the electrical insulation between adjacent pixels 180. The dielectric material or insulating material may include, but is not limited to, oxide materials including SiO2, or nitride materials including Si3N4, or silicon materials including amorphous silicon, polycrystalline silicon, monocrystalline silicon, or epitaxial silicon. In some embodiments, the isolation region 102 extends from the first surface (e.g., the top surface) 121 of the substrate 120 to a predetermined depth below the first surface 121.

[0071] In some embodiments, as shown in FIG1A and 1B, the isolation region 102 surrounds the absorption region 110 and the additional region 150. In some embodiments, the isolation region 102 surrounds the absorption region 110, and the isolation region 102 may be located between the absorption region 110 and the additional region 150.

[0072] In some embodiments, the isolation region 102 defines the boundary of the pixel 180. As shown in Figures 1A and 1B, the pixel 180 may include the isolation region 102, the absorption region 110, and the supplementary region 150. In some embodiments, the supplementary region 150 may be another isolation structure besides the isolation region. Therefore, by combining the supplementary region 150 with the isolation region 102, signal crosstalk between adjacent pixels 180 can be further reduced.

[0073] FIG2A depicts a top view of an example of a light detection device 200 according to one or more embodiments of the present application. FIG2B depicts a cross-sectional view of the light detection device 200 in FIG2A along line A-A' according to one or more embodiments of the present application.

[0074] The light detection device 200 includes a plurality of pixels 280 separated from each other by one or more additional regions 250. The light detection device 200 includes a first isolation region 202 and / or an additional second isolation region 240 formed in a substrate 220 (e.g., substrate 120 of FIG. 1A-1B). As shown in FIG. 2B, the first isolation region 202 and the second isolation region 240 may be opposite to each other in a direction perpendicular to a first surface 221 or a second surface 222 of the substrate 220.

[0075] Each pixel 280 includes an absorption region 210. The absorption region 210 may be substantially the same as the absorption region 110 of FIG. 1A-1B or the absorption region 310 of FIG. 3A-3C, which will be detailed below. The absorption region 210 is supported by a substrate 220 and surrounded by a first isolation region 202 and / or a second isolation region 240. The first isolation region 202 and / or the second isolation region 240 are substantially separated from the absorption region 210. In some embodiments, the distance between two adjacent pixels 280 is measured between two adjacent absorption regions 210. In some embodiments, the distance between two adjacent pixels 280 is measured between the centers of two adjacent absorption regions 210.

[0076] Unlike the photodetector 100 in Figures 1A-1B, where the additional region 150 is surrounded by the isolation region 102, in the photodetector 200, the additional region 250 is located outside the first isolation region 202 and / or the second isolation region 240. In some embodiments, as shown in Figures 2A-2B, each absorption region 210 is surrounded by four adjacent additional regions 250.

[0077] The materials and functions of the first isolation zone 202 and / or the second isolation zone 240 are similar to or the same as those of the isolation zone 102 described above. In some embodiments, the second isolation zone 240 may be formed by back side deep trench isolation (BDTI).

[0078] In some embodiments, the first isolation region 202 extends from a first surface (e.g., top surface) 221 of the substrate 220 to a predetermined depth below the first surface 221. In some embodiments, the second isolation region 240 extends from a second surface (e.g., bottom surface) 222 of the substrate 220 opposite to the first surface 221 to a predetermined depth on the second surface 222. In some embodiments, the isolation region penetrates the substrate 220 from the first surface 221 to the second surface 222. That is, the first isolation region 202 and the second isolation region 240 can be a single, integrated isolation region.

[0079] In some embodiments, the photodetector 200 includes a blocking layer 204 surrounding at least a portion of the absorption region 210. In some embodiments, the conduction type of the blocking layer 204 is the same as the first conduction type of the absorption region 210. The blocking layer 204 can prevent light-generated charges in the absorption region 210 from reaching the substrate 220, thereby improving the photogenerated carrier collection efficiency of the photodetector 200. The blocking layer 204 can also prevent light-generated charges in the substrate 220 from reaching the absorption region 210, thereby improving the photogenerated carrier velocity of the photodetector 200.

[0080] The material of the barrier layer 204 may be the same as, different from, the material of the absorption region 210, the substrate 220, or the combined material of the absorption region 210 and the substrate 220. In some embodiments, the barrier layer 204 may be annular, but is not limited thereto. In some embodiments, the barrier layer 204 may reach the first surface 221 of the substrate 220. In some embodiments, the barrier layer 204 includes dopants, and the peak concentration of the dopants is in the range of 1 × 10¹⁵ cm⁻³ to 1 × 10²⁰ cm⁻³. The barrier layer 204 may reduce crosstalk between two adjacent pixels 280.

[0081] In some embodiments, the interface layer 205 is deposited along the trench sidewalls and trench bottom of the substrate 220, and then selectively grown over it in the absorption region 210. In some embodiments, the additional region 250 may also include the interface layer 205. In some embodiments, the interface layer 205 may include monocrystalline silicon to improve the growth quality of subsequently grown layers.

[0082] In some embodiments, the photodetector 200 further includes a passivation layer 207 disposed on a first surface 221 of the absorption region 210. In some embodiments, the passivation layer 207 may also cover a portion of the first surface 221 of the substrate 220. In some embodiments, the absorption region 210 protrudes at least partially from the first surface 221 of the substrate 220, and the passivation layer 207 also covers the sidewalls of the absorption region 210 exposed outside the substrate 220. The passivation layer 207 may include amorphous silicon, polycrystalline silicon, epitaxial silicon, alumina (e.g., AlxOy), silicon oxide (e.g., SixOy), germanium oxide (e.g., GexOy), germanium silicon (e.g., GeSi), silicon nitride families (e.g., SixNy), high-k materials (e.g., HfOx, ZnOx, LaOx, LaSiOx), and any combination of the above materials. The included passivation layer 207 can provide a variety of benefits. For example, passivation layer 207 can be used as a surface passivation layer for absorption region 210 to help reduce dark current or leakage current caused by defects on the exposed surface of absorption region 210.

[0083] Additional area 250 may be substantially the same as additional area 150 of Figures 1A-1B.

[0084] In some embodiments, the additional region 250 may include a photodiode or an output electrical signal from the absorption region 110 for calibration purposes. That is, a portion of the additional region 250 may be an additional absorption region 206 with bits between the interface layer 205 and the passivation layer 207. In these embodiments, the light shield may include an optical window corresponding to the additional region 250.

[0085] FIG2C depicts a cross-sectional view of the photodetector in FIG2A along line A-A' according to one or more embodiments of the present application. In some embodiments, the photodetector 200 may include additional blocking layers 204 surrounding the corresponding additional region 150 to further reduce the dark current of the photodetector 200.

[0086] Figures 3A-3C depict an example light detection device 300. The light detection device 300 includes a plurality of pixels 380 arranged in an array.

[0087] Similar to pixel 180 in FIG1A-1B, pixel 380 of the light detection device 300 includes an absorption region 310 and one or more additional regions 350 formed on a substrate 320 (e.g., 120 in FIG1B or 220 in FIG2B). A first isolation region 302 (e.g., 102 in FIG1A-1B or 202 in FIG2A-2B) and / or a second isolation region 340 (e.g., second isolation region 240 in FIG2A-2B) defines the boundary of pixel 380.

[0088] Adjacent pixels 380 are separated or isolated from each other by the first isolation region 302 and / or the second isolation region 340. Unlike the photodetector 200 where the additional region 250 is disposed outside the first isolation region 202 and the second isolation region 240, in the photodetector 300, the additional region 350 is surrounded by the first isolation region 302 and / or the second isolation region 340. As shown in Figures 3A-3B, the additional region 350 is located between the absorption region 310 and the first isolation region 302 and / or the second isolation region 340.

[0089] In some embodiments, each pixel 380 of the photodetector 300 includes two switches S1, S2 electrically coupled to the absorption region 310. The switches S1, S2 may be the switches S1, S2 detailed in Figures 3C, 7A-7E. Each switch S1, S2 includes a corresponding control region C1, C2 and a corresponding readout region R1, R2. The control regions C1, C2 are each coupled to a corresponding control signal (e.g., a first control signal or a second control signal), and the readout regions R1, R2 are each coupled to a readout circuit (e.g., 1054 in Figure 10B, wherein the readout circuit 1054 may include a first sub-readout circuit and a second readout circuit respectively coupled to the readout regions R1, R2).

[0090] In some embodiments, readout regions R1 and R2 each include a corresponding carrier output region 311 belonging to a conduction type (e.g., n-type). In some embodiments, control regions C1 and C2 each include a carrier control region 312 belonging to a conduction type (e.g., p-type). In some embodiments, carrier output regions 311 and carrier control regions 312 are formed in absorption region 310. In some embodiments, carrier output regions 311 and carrier control regions 312 are formed in substrate 320. In some embodiments, readout regions R1 and R2 each include a readout electrode (730a, 730b detailed in Figures 7A-7E) disposed on absorption region 310 or substrate 320, depending on the location of carrier output region 311 and carrier control region 312. Control regions C1 and C2 each include control electrodes (740a and 740b as detailed in Figures 7A-7E) disposed on the absorption region 310 or the substrate 320, depending on the positions of the carrier output region 311 and the carrier control region 312.

[0091] In some embodiments, a first control signal and a second control signal control the control regions C1 and C2 of the switch S1 and S2, respectively, to control the movement direction of electrons or holes generated by absorbed photons in the absorption region 310. 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 is generated between the two portions directly below the control electrode and in the absorption region 310 or the substrate 320. Depending on the direction of the electric field, photocarriers in the absorption region 310 drift towards one of the portions directly below the readout electrode. In some embodiments, the first control signal has a first phase and the second control signal has a second phase, and the first control phase and the second control phase do not overlap. 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 variable voltage signal, such as a sinusoidal signal operating between 0V and 3V, a time pulse signal, or a pulse signal. The drift direction of the carriers generated from the absorption region 310 depends on the direction of the bias voltage value. The control signal is a modulation signal.

[0092] In some embodiments, the first isolation region 302 and / or the second isolation region 340 are doped regions, and their conduction type may be different from or the same as that of the carrier output region 311 in the readout regions R1 and R2. The materials and functions of the first isolation region 302 and / or the second isolation region 340 are similar to or the same as those of the isolation region 102 described above.

[0093] In some embodiments, the carrier output region 311 and the carrier control region 312 are formed in the substrate 320 and located outside the absorption region 310 to reduce the dark current of the photodetector 300. In some embodiments, the carrier output region 311 and the carrier control region 312 may or may not be provided in the additional region 350.

[0094] The material and / or properties of the additional region 350 are similar to or the same as those described above. For example, each additional region 350 may also include an additional absorption region 306 (e.g., 206 in Figure 2B) located between the interface layer 305 (e.g., 205 in Figure 2B) and the passivation layer 307 (e.g., 207 in Figure 2B) for correction purposes.

[0095] FIG4A depicts a top view of a light detection device 400 according to one or more embodiments of the present application. FIG4B depicts a cross-sectional view of the light detection device 400 in FIG4A along line A-A' according to one or more embodiments of the present application.

[0096] The photodetector 400 includes an absorption region 410 supported by a substrate 420 and one or more additional regions 450 formed in or on the substrate 420. In some embodiments, as shown in FIG4A, the absorption region 410 is located between two additional regions 450 disposed on opposite sides of the absorption region 410.

[0097] The same elements as described above are identified by the same reference numerals and names in Figures 4A and 4B. For example, the absorption region 410 may be similar to the absorption region 110 of Figures 1A-1B, 210 of Figures 2A-2B, or 310 of Figures 3A-3C. The substrate 420 may be similar to the substrate 120 of Figure 1B, 220 of Figure 2B, or 320 of Figure 3B. The additional region 450 may be similar to the additional region 150 of Figures 1A-1B, 250 of Figures 2A-2B, or 350 of Figures 3A-3B.

[0098] In some embodiments, the photodetector 400 includes a doped region 408 formed in a substrate 420 and in contact with the absorption region 410. An electrode 460 may be formed above a first surface of the substrate 420. The doped region 408 may be doped with a first conduction type (e.g., p-type) for collecting a second portion (e.g., a hole) of photocarriers generated by the absorption region 410. In some embodiments, the doped region 408 is doped with a dopant (e.g., boron) with a peak doping concentration higher than the first peak doping concentration of the absorption region 410.

[0099] The photodetector 400 may be a dual-switch photodetector. As shown in FIG4A, the photodetector 400 includes two switches S1 and S2 electrically coupled to the absorption region 410 and partially formed in the substrate 420. The switches S1 and S2 may be similar to the switches S1 and S2 of FIG3A-3C or the switches S1 and S2 detailed in FIG7A-7D. The switches S1 and S2 are located on the same side of the absorption region 410.

[0100] Each of the two switches S1 and S2 includes readout electrodes 430a and 430b and control regions C1 and C2 having control electrodes 440a and 440b. The two readout electrodes 430a and 430b may each be formed above a first surface of the substrate 420 and electrically coupled to the absorption region 410, for collecting a first portion (e.g., electrons) of the photocarriers generated by the absorption region 410. In some embodiments, the control electrodes 440a and 440b are formed above the first surface of the substrate 420 and are separated from the absorption region 410.

[0101] In some embodiments, as shown in FIG4B, the photodetector 400 includes a low barrier region 470 (e.g., low barrier region 610 detailed in FIG6A-6E) in the substrate 420 and in contact with the absorption region 410.

[0102] In some embodiments, as shown in FIG4A, the first switch S1 includes a carrier output region 402a below the readout electrode 430a, and the second switch S2 includes a carrier output region 402b below the readout electrode 430b. In some embodiments, the carrier output regions 402a and 402b are of a two-conduction type (e.g., n-type). In some embodiments, the carrier output regions 402a and 402b are doped with a dopant (e.g., phosphorus) at a peak doping concentration.

[0103] Since the doped region 408 is formed within the substrate 420 rather than within the absorption region 410, the electrodes 460, readout electrodes 430a, 430b, and control electrodes 440a, 440b can all be formed coplanarly above the first surface of the substrate 420. Therefore, the height difference between the electrode 460 and any two of the readout electrodes 430a, 430b and control electrodes 440a, 440b can be reduced, thus benefiting subsequent processes. Furthermore, the area of ​​the absorption region 410 that absorbs optical signals can also be larger.

[0104] FIG5A depicts a cross-sectional view of a photodetector 500a according to one or more embodiments of the present application. The photodetector 500a may be a photodiode and may be configured for any suitable application.

[0105] In some embodiments, as shown in FIG5A, the photodetector 500a includes an absorption region 510 (e.g., absorption region 110 of FIG1A-1B, 210 of FIG2A-2B, 310 of FIG3A-3C, and 410 of FIG4A-4B) and a substrate 520 supporting the absorption region 510 (e.g., substrate 120 of FIG1B, 220 of FIG2B, 320 of FIG3A-3B, or 420 of FIG4A-4B). The absorption region 510 is configured to receive an optical signal and generate photocarriers in response to the optical signal. In some embodiments, an output electrical signal is determined by the photocarriers generated by the absorption region 510. The substrate 520 includes a first material (e.g., silicon), and the absorption region 510 includes a second material (e.g., germanium) different from the first material. In some embodiments, the absorption region 510 is doped with a first dopant (e.g., boron) belonging to a first conduction type (e.g., p-type).

[0106] The photodetector 500a may further include a density compensation region 540 supported by the substrate 520 and separated from the absorption region 510. The density compensation region 540 may include a second material (e.g., germanium) and may be doped with a second dopant (e.g., phosphorus) belonging to a second conductivity type (e.g., n-type) opposite to the first conductivity type (e.g., p-type) of the absorption region 510. In some embodiments, the substrate 520 is made of silicon, the absorption region 510 is made of germanium, and the density compensation region 540 is made of germanium. In some embodiments, at least one of the absorption region 510 or the density compensation region 540 is partially or completely embedded in the substrate 520 (e.g., as shown in FIG. 8B or 8C).

[0107] The photodetector 500a may further include a first electrode 530 (e.g., the first electrode 130 in FIG1A-1B) formed above the first surface 541 of the density compensation region 540 and electrically coupled to the density compensation region 540 and the absorption region 510, for collecting a first portion (e.g., electrons) of the photocarriers generated by the absorption region 510.

[0108] The density compensation region 540 can improve pixel performance and process yield. From a process point of view, the density compensation region 540 can be a density compensation (e.g., a simulated region). That is, to achieve a more ideal distribution of material (e.g., more uniform pattern density, higher overall density, center / edge compensation, etc.) formed in or on the substrate in trenches or recesses of the substrate, and which is different from the material of the substrate, thereby improving the device yield of the entire wafer. In some embodiments, when the third material is the same as the second material, the density compensation region 540 can achieve a more ideal distribution of light-absorbing material on the substrate (e.g., more uniform pattern density, higher overall density, center / edge compensation, etc.), thereby improving the device yield of the entire wafer. However, if the density compensation region 540 is only used as a simulated region, the overall usable area of ​​the device will be reduced. By coupling an electrode (e.g., the first electrode 530) to the density compensation region 540 and doping the density compensation region 540 with a dopant different from that of the absorption region 510, the density compensation region 540 can be made into a usable area (e.g., for reading out photocarriers detected by the absorption region 510). This can improve the process yield of the device without sacrificing the usable wafer area.

[0109] In some embodiments, the photodetector 500a further includes a second electrode 560 (e.g., 160 in FIG. 1A-1B or 460 in FIG. 4A-4B) that may be formed on the first surface 521 of the substrate 520 or the first surface 511 of the absorption region 510 and electrically coupled to the absorption region 510. The second electrode 560 is configured to collect a second portion (e.g., a hole) of photocarriers generated by the absorption region 510.

[0110] In some embodiments, a first portion of the photocarriers collected by the first electrode 530, such as electrons, is different from a second portion of the photocarriers collected by the second electrode 560, such as holes. The collected photocarriers may be processed by different circuit systems, such as readout circuit systems (e.g., readout circuit 1054 of FIG. 10B).

[0111] In some embodiments, the absorption region 510 includes a first surface 511, a second surface 512, and one or more side surfaces 513. The second surface 512 is located between the first surface 511 of the absorption region 510 and the second surface 512 of the substrate 520. The side surfaces 513 are located between the first surface 511 and the second surface 512. In some embodiments, at least a portion of at least one of the first surface 511, the second surface 512, or the side surfaces 513 of the absorption region 510 is in direct contact with the substrate 520, thus forming a heterogeneous interface between the absorption region 510 and the substrate 520.

[0112] In some embodiments, the absorption region 510 is doped with a first dopant belonging to a first conduction type (e.g., p-type) and having a first peak doping concentration, and at least a portion of the substrate 520 (e.g., the low barrier region 610 described below) or the entire substrate 120 is substantially doped with a third dopant (e.g., phosphorus) belonging to a second conduction type (e.g., n-type) and having a second peak doping concentration. The ratio between the first peak doping concentration and the second peak doping concentration may be equal to or greater than a threshold ratio (e.g., 10). The third dopant may be the same as the second dopant in the density compensation region 540.

[0113] In some embodiments, the density compensation region 540 is doped with a second dopant belonging to a second conduction type (e.g., n-type) and having a third peak doping concentration. The third peak doping concentration may be higher than the second peak doping concentration of the substrate 520 or the low barrier region 610, so as to attract a first portion of photocarriers (e.g., electrons) to flow to the density compensation region 540 and then be collected by the first electrode 530.

[0114] In some embodiments, the photodetector 500a includes a first doped region 502 formed in the density compensation region 540. A first electrode 530 may be located above the first doped region 502. The first doped region 502 is doped with a dopant (e.g., phosphorus) belonging to a second conduction type (e.g., n-type) and having a fourth peak doping concentration. In some embodiments, the fourth peak doping concentration of the first doped region 502 is higher than the third peak doping concentration of the density compensation region 540.

[0115] In some embodiments, the photodetector 500a includes a second doped region 508 formed in the absorption region 510 and adjacent to the first surface 511 of the absorption region 510. A second electrode 560 may be located above the second doped region 508. The second doped region 508 may be doped with a first conductivity type (e.g., p-type). In some embodiments, the second doped region 508 is doped with a dopant (e.g., boron) whose peak doping concentration is higher than the first peak doping concentration of the absorption region 510.

[0116] FIG. 5B depicts a cross-sectional view of another photodetector 500b according to one or more embodiments of the present application. The photodetector 500b includes substantially the same structure as the photodetector 500a of FIG. 5A. However, unlike the photodetector 500a of FIG. 5A, the photodetector 500b includes a second doped region 508 formed outside the absorption region 510. A second electrode 560 is formed on a first surface 521 of a substrate 520. In some embodiments, as shown in FIG. 5B, the second doped region 508 is formed in the substrate 520, close to the first surface 521 of the substrate 520, and in contact with the absorption region 510 (e.g., the side surface 513 of the absorption region 510). Since the second doped region 508 is formed in the substrate 520 rather than within the absorption region 510, the area of ​​the absorption region 510 used to absorb optical signals can be larger.

[0117] FIG6A depicts a top view of a light detection device 600a according to one or more embodiments of the present application. FIG6B depicts a cross-sectional view of the light detection device 600a in FIG6A along line A-A'.

[0118] The photodetector 600a includes a structure substantially the same as that of the photodetector 500a of FIG. 5A. However, unlike the photodetector 500a, as shown in FIG. 6A-6B, the photodetector 600a includes a low barrier region 610 on the substrate 520. The low barrier region 610 may contact the absorption region 510. In some embodiments, at least a portion of the low barrier region 610 is located between the absorption region 510 and the density compensation region 540. In some embodiments, the low barrier region 610 is doped with a second conduction type (e.g., n-type) and its second peak doping concentration is lower than the third peak doping concentration of the density compensation region 540.

[0119] In some embodiments, in the photodetector 600a, as shown in FIG6A, the substrate 520 further includes a high barrier region (or a blocking region) 620, which is at least a portion of the contact absorption region 510. In some embodiments, the high barrier region 620 is doped with a fourth dopant (e.g., boron) belonging to a first conduction type (e.g., p-type). In some embodiments, the high barrier region 620 is formed in or partially within the substrate 520 and partially within the absorption region 510. The high barrier region 620 is configured to block or guide the flow of photocarriers.

[0120] In some embodiments, the substrate 520 may be uniformly doped with a third dopant (e.g., phosphorus). In some embodiments, the substrate 520 may be regionally doped with a third dopant (e.g., phosphorus) to form a low barrier region 610. The low barrier region 610 may be configured to guide a first portion (e.g., electrons) of photocarriers generated by the absorption region 510 to move in a confined region. Since the third peak doping concentration of the density compensation region 540 is higher than the second peak doping concentration of the low barrier region 610, the first portion (e.g., electrons) of photocarriers may flow from the absorption region 510 through the low barrier region 610 to the density compensation region 540, and then be collected by the first electrode 530. In some embodiments, the low barrier region 610 is in contact with both the absorption region 510 and the density compensation region 540 to facilitate carrier transport between the absorption region 510 and the first doped region 502 formed within the density compensation region 540.

[0121] Other portions of the substrate 520 not doped with the second dopant can serve as high barrier region 620. In some embodiments, high barrier region 620 can be an intrinsic material and can be doped with a second dopant whose peak concentration is lower than that of low barrier region 610, or with a dopant whose conduction type is different from that of the second dopant. In some examples, the dopant in the first doped region 502 is n-type, the dopant in the density compensation region 540 is n-type, the dopant in the absorption region 510 is p-type, the dopant in the high barrier region 620 is p-type, and the dopant in the low barrier region 610 is n-type.

[0122] In some embodiments, if the first electrode 530 is used to collect electrons, the energy level barrier in the high barrier region 620 is higher than that in the low barrier region 610 for electrons. Therefore, electrons can be directed and collected by the first electrode 530. In some embodiments, the area of ​​the high barrier region 620 is larger than the area of ​​the low barrier region 610, which can restrict the path of carriers and guide the self-absorption region 510 away from the confinement region of carriers on the heterojunction, thereby reducing the dark current of the photodetector 600a.

[0123] In some embodiments, if the photodetector 600a is configured to collect electrons, the dopant in the high barrier region 620 is p-type, and the dopant in the density compensation region 540 is n-type. After photocarriers are generated in the absorption region 510, holes can be collected by the second electrode 560, while electrons can be blocked by the high barrier region 620 and move from the absorption region 510 through the low barrier region 610 to the density compensation region 540, without flowing out from the entire heterojunction between the absorption region 510 and the substrate 520, thereby reducing the dark current of the photodetector 600a.

[0124] FIG. 6C depicts a top view of another photodetector 600b according to one or more embodiments of the present application. The photodetector 600b includes a structure substantially the same as that of the photodetector 600a shown in FIG. 6A-6B. However, unlike the high barrier region 620 of the photodetector 600a in FIG. 6A-6B, the high barrier region 620 of the photodetector 600b extends and covers two or more sides of the absorption region 510 to further restrict carriers from flowing through the low barrier region 610 without escaping from the other sides of the absorption region 510. The peak doping concentration of the high barrier region 620 may be higher or lower than the peak doping concentration of the second doped region 508. In some embodiments, the high barrier region 620 and the second doped region 508 are formed by two different process steps, such as using different photomasks.

[0125] In some embodiments, the first peak doping concentration of the absorption region 510 may be in the range of 1x10¹⁶ cm⁻³ to 1x10²⁰ cm⁻³. In some embodiments, the peak doping concentration of the high barrier region 620 may be equal to or greater than 1x10¹⁶ cm⁻³.

[0126] In some embodiments, the ratio between the first peak doping concentration and the second peak doping concentration of the substrate 520 or the low barrier region 610 is equal to or greater than 10, thus the photodetector, such as 500a, 500b, 600a, or 600b, can further reduce dark current. In some embodiments, the ratio of the first peak doping concentration to the second peak doping concentration is equal to or greater than 100, thus the photodetector can further reduce dark current while simultaneously improving quantum efficiency.

[0127] FIG6D depicts a top view of another light detection device 600c according to one or more embodiments of the present application. FIG6E depicts a cross-sectional view of the light detection device 600c in FIG6D along line A-A'.

[0128] The photodetector 600c includes a structure substantially the same as that of the photodetector 600b of FIG. 6C, and may include a low barrier region 610 and a high barrier region 620 substantially the same as those in the photodetector 600c. The photodetector 600c is also similar to the photodetector 500b of FIG. 5B, and includes a second doped region 508 formed outside the absorption region 510, wherein the second doped region 508 is similar to the second doped region 508 of the photodetector 500b. In some embodiments, as shown in FIG. 6E, the second doped region 508 is formed in the substrate 520, close to the first surface 521 of the substrate 520, and in contact with the absorption region 510 (e.g., the side surface 513 of the absorption region 510).

[0129] The optical detection device may include one or more switches. As described below, Figures 7A-7D depict dual-switch optical detection devices with different configurations, while Figure 7E depicts a single-switch optical detection device.

[0130] FIG7A depicts a top view of the dual-switcher photodetector 700a according to one or more embodiments of the present application. FIG7B depicts a cross-sectional view of the dual-switcher photodetector 700a in FIG7A along line A-A' according to one or more embodiments of the present application.

[0131] The dual-switcher photodetector 700a can be a pixel in an i-ToF (Time-of-Flight) sensor. The photodetector 700a includes a substrate 520 (e.g., substrate 120 of FIG. 1B, 220 of FIG. 2B, 320 of FIG. 3B, 420 of FIG. 4A-4B, or 520 of FIG. 5A-5B and 6A-6E) and an absorption region 510 supported by the substrate 520 (e.g., absorption region 110 of FIG. 1A-1B, 210 of FIG. 2A-2B, 310 of FIG. 3A-3C, 410 of FIG. 4A-4B, or 510 of FIG. 5A-5B and 6A-6E). The absorption region 510 is configured to receive an optical signal and generate photocarriers in response to the optical signal. The substrate 520 includes a first material (e.g., silicon), and the absorption region 510 includes a second material (e.g., germanium) different from the first material. The absorption region 510 may be doped with a first dopant (e.g., boron) belonging to the first conductivity type (e.g., p-type).

[0132] The photodetector 700a further includes one or more density compensation regions 540a, 540b supported by the substrate 520 and separated from the absorption region 510. Each density compensation region 540a, 540b may be the density compensation region 540 of Figures 5A-5B or 6A-6E. In some embodiments, at least a portion of the absorption region 510 or at least a portion of one or more density compensation regions 540a, 540b is embedded in the substrate 520.

[0133] Each density compensation region 540a, 540b may include a second material and be doped with a second dopant (e.g., phosphorus) belonging to a second conductivity type opposite to the first conductivity type (e.g., n-type). In some embodiments, the substrate 520 is made of silicon, the absorption region 510 is made of germanium, and one or more density compensation regions 540a, 540b are made of germanium.

[0134] As shown in FIG7B, the photodetector 700a includes two switches S1 and S2 electrically coupled to the absorption region 510 and partially formed in the substrate 520. Each of the two switches S1 and S2 includes readout electrodes 730a and 730b (e.g., the first electrode 530 in FIG5A-5B, 6B, or 6E) and a control region C1 and C2 provided with control electrodes 740a and 740b. Each readout electrode 730a and 730b is formed above the first surface 541 of the corresponding density compensation region 540a and 540b and electrically coupled to the corresponding density compensation region 540a and 540b and the absorption region 510, for collecting a first portion (e.g., electrons) of the photocarriers generated by the absorption region 510. In some embodiments, the control electrodes 740a and 740b are formed above the first surface 521 of the substrate 520 and separated from the absorption region 510.

[0135] In some embodiments, the photodetector 700a includes a low barrier region 610 (e.g., the low barrier region 610 in Figures 6A-6E) located within the substrate 520 and in contact with the absorption region 510. In some embodiments, at least a portion of the low barrier region 610 is located between the absorption region 510 and one or more density compensation regions 540a, 540b. In some embodiments, the low barrier region 610 is in contact with both the absorption region 510 and the density compensation region 540.

[0136] In some embodiments, in the photodetector 700a, the absorption region 510 has a first peak doping concentration, and the substrate 520 or the low barrier region 610 is doped with a third dopant (e.g., phosphorus) belonging to a second conduction type (e.g., n-type) and having a second peak doping concentration. The ratio between the first peak doping concentration of the absorption region 510 and the second peak doping concentration of the substrate 520 may be equal to or greater than 10.

[0137] In some embodiments, similar to the density compensation regions 540 of Figures 5A-5B and 6A-6E, at least one of one or more density compensation regions 540a, 540b may have a third peak doping concentration, which is higher than the second peak doping concentration in the substrate 520 or the low barrier region 610, so as to attract a first portion of photocarriers (e.g., electrons) to flow into the density compensation regions 540a, 540b, and then be collected by the corresponding readout electrodes 730a, 730b.

[0138] In some examples, the second peak doping concentration of the substrate 520 or the low barrier region 610 is in the range of 1 x 10¹⁵ cm⁻³ to 1 x 10¹⁷ cm⁻³. In some examples, the third peak doping concentration of the density compensation regions 540a and 540b is in the range of 1 x 10¹⁷ cm⁻³ to 1 x 10¹⁸ cm⁻³.

[0139] In some embodiments, the photodetector 700a is configured to receive two control signals (e.g., a first control signal and a second control signal) to control the control regions C1 and C2 of the two switches S1 and S2 respectively, so as to control the movement direction of electrons or holes generated by absorbing photons in the absorption region 510. The control signal may be a modulation signal.

[0140] 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, an electric field is generated between the two portions directly below the control electrodes 740a and 740b and in the absorption region 510. Depending on the direction of the electric field, the free carriers in the absorption region 510 will drift toward one of the portions directly below the readout electrodes 730a and 730b. In some embodiments, the first control signal includes a first phase, and the second control signal includes a second phase, the first control phase and the second control phase do not overlap. 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, the bias value ΔV is generated by a variable voltage signal, such as a sinusoidal signal, a time pulse signal, or a pulse signal operating between 0V and 3V. The direction of the bias value ΔV determines the drift direction of the carriers generated in the absorption region 510.

[0141] In some embodiments, as shown in FIG7A and 7B, the first switch S1 includes a carrier output region 702a (e.g., carrier output region 311 in FIG3B-3C or carrier output region 402a in FIG4A) located below the readout electrode 730a, and the second switch S2 includes a carrier output region 702b (e.g., carrier output region 311 in FIG3B-3C or carrier output region 402a in FIG4A) located below the readout electrode 730b. In some embodiments, the carrier output regions 702a and 702b are formed in density compensation regions 540a and 540b, respectively. In some embodiments, the first carrier output regions 702a and 702b belong to a second conduction type (e.g., n-type). In some embodiments, the first carrier output regions 702a and 702b are doped with a dopant (e.g., phosphorus) and have a peak doping concentration. In some embodiments, the peak doping concentrations of the first carrier output regions 702a and 702b are higher than the third peak doping concentrations of the density compensation regions 540a and 540b, respectively.

[0142] In some embodiments, the peak doping concentration of the first carrier output regions 702a, 702b depends on the materials of the readout electrodes 730a, 730b and the substrate 520. The peak doping concentration may be between 5 x 10¹⁸ cm⁻³ and 5 x 10²⁰ cm⁻³. The first carrier output regions 702a, 702b are carrier collection regions used to collect a first portion (e.g., electrons) of the photocarriers generated by the absorption region 510 based on the control of two control signals.

[0143] FIG. 7C depicts a cross-sectional view of another photodetector 700b according to one or more embodiments of the present application. The photodetector 700b includes a structure substantially the same as that of the photodetector 700a in FIG. 7A-7B. However, in the photodetector 700a, the readout electrodes 730a, 730b and the control electrodes 740a, 740b are disposed on different sides of the absorption region 510. In contrast, in the photodetector 700b, as shown in FIG. 7C, the readout electrodes 730a, 730b and the control electrodes 740a, 740b are disposed on the same side of the absorption region 510 along the first direction D1. The control electrodes 740a, 740b may be arranged along a second direction perpendicular to the first direction D1.

[0144] In the photodetector 700b, the readout electrodes 730a and 730b may be arranged along a second direction perpendicular to the first direction. The control electrodes 740a and 740b may be arranged between the readout electrodes 730a and 730b and the absorption region 510.

[0145] In some embodiments, as shown in FIG7C, readout electrodes 730a and 730b on the same side of the absorption region 510 may be disposed on top of the density compensation region 540. At least a portion of the low barrier region 610 is located between the absorption region 510 and the density compensation region 540 to facilitate carrier transport.

[0146] FIG. 7D depicts a cross-sectional view of another photodetector 700c according to one or more embodiments of the present application. The photodetector 700c includes a structure substantially the same as that of the photodetector 700b in FIG. 7C. However, unlike the photodetector 700b, which has readout electrodes 730a, 730b disposed on top of the same density compensation region 540, the photodetector 700c includes two readout electrodes 730a, 730b disposed on corresponding two density compensation regions 540a, 540b. In some embodiments, at least a portion of the low barrier region 610 is located between the absorption region 510 and the density compensation region 540 to facilitate carrier transport.

[0147] FIG. 7E depicts an exemplary single-switcher photodetector 700d. The single-switcher photodetector 700d has a substantially identical structure to the dual-switcher photodetectors 700a, 700b, or 700c, except that the single-switcher photodetector 700d has only a single switch S (e.g., S1 or S2 in FIG. 7A-7D), which includes a readout electrode 730 (e.g., 730a or 730b in FIG. 7A-7D) disposed on top of the density compensation region 540 (e.g., 540, 540a, or 540b in FIG. 7A-7D) and a control region C (e.g., C1 or C2 in FIG. 7A-7D) provided with a control electrode 740 (e.g., 740a or 740b in FIG. 7A-7D). In some embodiments, at least a portion of the low barrier region 610 is located between the absorption region 510 and the density compensation region 540 to facilitate carrier transport.

[0148] 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 second doped region 508 in Figures 7A to 7E may be formed in the substrate 520, as shown in Figure 6D. The second electrode 560 may be located on the first surface 521 of the substrate 520. As another example, the photodetectors 700b, 700c, 700d may further include a high barrier region (e.g., the high barrier region 620 in Figures 6A-6E) that contacts the absorption region 510. In some embodiments, the high barrier region may contact at least the portion of the absorption region 510 that does not contact the low barrier region 610, thereby blocking and further limiting the flow of carriers through the low barrier region 610 to the readout electrodes (e.g., readout electrodes 730a, 730b, 730) disposed on the side of the low barrier region 610. As another example, the photodetector 100 may also include a barrier layer 204 surrounding the additional region 150. The second doped region 108 of the photodetector 100 may be formed in the substrate 120 in a manner similar to that described in FIG. 4A. In some embodiments, unless otherwise stated, the cross-sectional views shown in this application may be cross-sectional views of the photodetector in any possible cross-sectional direction.

[0149] Figures 8A-8C are cross-sectional views depicting portions 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. The photodetector includes an absorption region 810 (e.g., absorption region 110 of Figures 1A-1B, 210 of Figures 2A-2B, 310 of Figures 3A-3C, 410 of Figures 4A-4B, or 510 of any of Figures 5A-5B, 6A-6E, or 7A-7E) and a substrate 820 (e.g., substrate 120 of Figure B1, 220 of Figure 2B, 320 of Figure 3B, 420 of Figures 4A-4B, or 520 of any of Figures 5A-5B, 6A-6E, or 7A-7E). The substrate 820 has a surface 801 (e.g., surface 521 of any of Figures 5A-5B).

[0150] In some embodiments, as shown in FIG8A, the absorption region 810 is entirely on the surface 801 of the substrate 820. In some embodiments, as shown in FIG8B, the absorption region 810 is partially embedded in the substrate 820. That is, a portion of each side of the absorption region 810 (e.g., side 513 of FIG5A or 5B) is in contact with the substrate 820. In some embodiments, as shown in FIG8C, the absorption region 810 is completely embedded within the substrate 820. That is, the entire side of the absorption region 810 is in contact with the substrate 820.

[0151] Figures 9A-9D depict exemplary arrangements of the control area of ​​a switcher in 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 400 in Figures 4A-4B, 700a, 700b, 700c, or 700d in Figures 7A-7E. The switcher may be switch S1 or S2 in Figures 4A-4B or 7A-7E. The control area may be control area C1, C2, or C in Figures 4A-4B or 7A-7E. The control area may include a control electrode 940 (e.g., control electrodes 440a, 440b in Figures 4A-4B or 740a, 740b, or 740 in Figures 7A-7E).

[0152] In some embodiments, as shown in FIG9A, the control electrode 940 may be disposed above a first surface 901 of a structure 910, the structure 910 having an essential region with bits directly below the control electrode 940. The structure 910 may be a substrate (e.g., substrate 120 of FIG. B1, 220 of FIG. 2B, 320 of FIG. 3B, 420 of FIG. 4A-4B, or 520 of any of FIG. 5A-5B, 6A-6E, 7A-7E, or 8A-8C) or an absorption region (e.g., absorption region 110 of FIG. 1A-1B, 210 of FIG. 2A-2B, 310 of FIG. 3A-3C, 410 of FIG. 4A-4B, or 510 of any of FIG. 5A-5B, 6A-6E, 7A-7E, or 8A-8C). The control electrode 940 forms a Schottky contact, an Ohmic contact, or a combination of intermediate characteristics, depending on various factors including the substrate material, the absorption region material, the passivation layer material (e.g., passivation layer 207 of Figure 2B or 3B), and / or the control electrode 940 material, and / or the degree of defects or dopants in the substrate, absorption region, or passivation layer.

[0153] In some embodiments, as shown in FIG9B, the control region of the switch further includes a doped region 903 (e.g., carrier control region 312 of FIG3B) located below the control electrode 940 and within the structure 910 (e.g., substrate or absorption region). In some embodiments, the doped region 903 may be of a different conduction type than the carrier collection region (e.g., the first carrier output regions 702a, 702b of FIG7A-7B). In some embodiments, the doped region 903 includes dopants and a range of dopant concentrations. The peak dopant concentration of the doped region 903 depends on the material of the control electrode 940 and / or the material of the structure 910, and / or the degree of doping or defects in the structure 910 (e.g., substrate). The peak dopant concentration may be, for example, in the range of 1 x 10¹⁷ cm⁻³ to 5 x 10²⁰ cm⁻³. The doped region 903 may form a Schottky or ohmic contact or a combination thereof with the control electrode 940. The doped region 903 is used to demodulate the carriers generated by the absorption region based on the control signal.

[0154] In some embodiments, as shown in FIG9C, the control region of the switch further includes a dielectric layer 950 that may be formed between the structure 910 (e.g., a substrate or absorption region) and the control electrode 940. The dielectric layer 950 prevents direct current conduction from the control electrode 940 to the structure 910, but allows an electric field to be established in the structure 910 when a voltage is applied to the control electrode 940. The establishment of an electric field between the two control regions, for example between control regions C1 and C2, can attract or repel charge carriers within the structure 910.

[0155] In some embodiments, as shown in FIG9D, the control region of the switch simultaneously has a doped region 903 and a dielectric layer 950. The doped region 903 may be a carrier control region located below the control electrode 940 and in the structure 910 (e.g., carrier control region 312 of FIG3B). The dielectric layer 950 may be located between the doped region 903 and the control electrode 940.

[0156] In some embodiments, the dielectric layer 950 may include, but is not limited to, SiO2. In some embodiments, the dielectric layer 950 may include a high-k material, including but not limited to, Si3N4, SiON, SiNx, SiOx, GeOx, Al2O3, Y2O3, TiO2, HfO2, or ZrO2. In some embodiments, the dielectric layer 950 may include semiconductor materials, but are not limited to, amorphous silicon, polycrystalline silicon, crystalline silicon, germanium silicon, or combinations thereof.

[0157] Figure 10A is a block diagram of an exemplary embodiment of an imaging system 1000. The imaging system 1000 may include an imaging module 1010 and a software module 1020 for reconstructing a three-dimensional (3D) model 1030 of a detected target object 1002. The imaging system 1000 or the imaging module 1010 may be implemented in mobile devices (e.g., smartphones, tablets, vehicles, drones, etc.), auxiliary devices of mobile devices (e.g., wearable devices), automotive or fixed facility (e.g., factory) computing systems, robotic systems, monitoring systems, or any other suitable devices and / or systems.

[0158] The imaging module 1010 includes a transmitter unit 1014, a receiver unit 1016, and a controller 1012. In operation, the transmitter unit 1014 emits emitted light 1003 towards a target object 1002. The receiver unit 1016 receives reflected light 1005 reflected back from the target object 1002. The controller 1012 can drive at least the transmitter unit 1014 and the receiver unit 1016. In some embodiments, the receiver unit 1016 and the controller 1012 are implemented on a single semiconductor wafer, such as a system-on-a-chip (SoC). In some cases, the transmitter unit 1014 is implemented using two different semiconductor wafers, such as a laser emitter wafer on a group III-V substrate and a silicon laser driver wafer on a silicon substrate.

[0159] The transmitter unit 1014 may include one or more light sources, a control circuit system for controlling one or more light sources, and / or an optical structure for operating the light emitted by 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 peak wavelengths in the visible wavelength range (e.g., wavelengths 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 peak wavelengths above the visible wavelength range, such as 850 nm, 940 nm, 1050 nm, 1064 nm, 1310 nm, 1350 nm, 1550 nm, or any other suitable wavelength.

[0160] In some embodiments, the light emitted from the light source may be collimated by one or more optical structures. For example, one or more optical structures may include one or more collimating lenses.

[0161] The receiver unit 1016 may include one or more photodetectors according to any of the above embodiments. The receiver unit 1016 may also include a control circuit system for controlling the control circuit system and / or optical structure to manipulate light reflected from the target object 1002 toward one or more photodetectors. In some embodiments, the optical structure includes one or more lenses capable of receiving parallel light and focusing it toward one or more photodetectors.

[0162] In some embodiments, the controller 1012 includes a timing generator and a processing unit. The timing generator receives a reference clock signal and provides a timing signal to the transmitter unit 1014 to modulate the emitted light. The timing signal is also provided to the receiver unit 1016 to control the collection of photocarriers. The processing unit processes the photocarriers generated and collected by the receiver unit 1016 to determine the raw data of the target object 1002. The processing unit may include a control circuit system, one or more signal processors for processing the information output of the photodetector, and / or a computer storage medium, which may store instructions for determining the raw data of the target object 1002, or store the raw data of the target object 1002. For example, the controller in an i-ToF sensor uses the phase difference between the light emitted by the transmitter unit 1014 and the light received by the receiver unit 1016 to determine a distance between two points.

[0163] The software module 1020 can be used to perform functions such as face recognition, eye tracking, gesture recognition, 3D model scanning / recording, motion tracking, autonomous vehicles, and / or augmented reality / virtual reality.

[0164] Figure 10B shows a block diagram of an exemplary device 1050, such as receiver unit 1016 or controller 1012. Here, an image sensor array 1052 (e.g., a 240 x 620 pixel array) can be implemented using a light detection device that implements this application. A phase-locked loop (PLL) circuit 1070 (e.g., an integer-N PLL) can generate a time pulse signal (e.g., a four-phase system clock) for modulation and demodulation. These time pulse signals can be gated and / or regulated by a timing generator 1072 to preset integration times and various operating modes before being sent to the image sensor array 1052 and the external illumination driver 1080. A programmable delay line 1068 can be added to the path of the illumination driver 1080 to delay the time pulse signals.

[0165] A voltage regulator 1062 can be used to control the operating voltage of the image sensor. For example, an image sensor can use N voltage domains. A temperature sensor 1064 can be used for depth correction and power control, and the temperature sensor 1064 can be controlled by an integrated circuit (IC) controller 1066.

[0166] The readout circuit 1054 of the photodetector bridges the photodetector of the image sensor array 1052 to a line analog-to-digital converter (ADC) 1056, wherein the ADC output may be further processed and integrated in the digital domain by a signal processor 1058 before reaching the output interface 1074. In some embodiments, the readout circuit 1054 may employ a tri-transistor configuration, including a reset gate, a source follower, and a selection gate, or a quad-transistor configuration, adding a transmission gate, or any suitable circuitry capable of processing the collected charge.

[0167] Memory 1060 can be used to store the output of signal processor 1058. In some embodiments, output interface 1074 can be implemented using a two-wire 1.2 Gb / s D-PHY Mobile Industrial Processor Interface (MIPI) transmitter coupled to a MIPI interface, or using complementary metal-oxide-semiconductor (CMOS) output, forming a low-speed / low-cost system. Digital data further modulated by signal processor 1058 is transmitted through the MIPI interface for further processing.

[0168] All functional blocks described herein can be accessed via an integrated circuit bus (I2C) interface.

[0169] In some embodiments, the band gap of the substrate (e.g., any one of 120, 220, 320, 420, 520 in FIG. 1A-1B, FIG. 2A-2C, FIG. 3A-3C, FIG. 4A-4B, FIG. 5A-5B, 6A-6E, or 7A-7E, 820 in FIG. 8A-8C, or 910 in FIG. 9A-9D) is greater than the band gap of the absorption region (e.g., 110, 210, 310, 410, 510 in FIG. 1A-1B, 2A-2C, 3A-3C, 4A-4B, 5A-5B, 6A-6E, or 7A-7E, 810 in FIG. 8A-8C, or 910 in FIG. 9A-9D). In some embodiments, the absorption region comprises or is made of a semiconductor material. In some embodiments, the substrate comprises or is made of a semiconductor material. In some embodiments, the absorption region comprises or is made of a group III-V semiconductor material. In some embodiments, the substrate comprises or is made of a group III-V semiconductor material. Group III-V semiconductor materials may include, but are not limited to, GaAs / AlAs, InP / InGaAs, GaSb / InAs, or InSb. For example, in some embodiments, the absorption region comprises or is made of InGaAs, and the substrate comprises or is made of InP. In some embodiments, the absorption region comprises or is made of a semiconductor material comprising group IV elements, such as Ge, Si, or Sn. In some embodiments, the absorption region comprises or is made of SixGeySn1-xy, where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1. In some embodiments, the absorption region comprises or is made of Ge1-aSna, where 0 ≦ a ≦ 0.1. In some embodiments, the absorption region comprises or is made of GexSi1-x, where 0 ≦ x ≦ 1. In some embodiments, the absorption region formed by intrinsic germanium is p-type due to material defects formed during the fabrication of the absorption region, wherein the defect density is 1 x 10¹⁴ cm⁻³ to 1 x 10¹⁶ cm⁻³. In some embodiments, the substrate comprises or is composed of a semiconductor material comprising group IV elements, such as Ge, Si, or Sn. In some embodiments, the substrate comprises or is composed of SixGeySn¹-xy, wherein 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1. In some embodiments, the substrate comprises or is composed of Ge¹-aSna, wherein 0 ≦ a ≦ 0.1. In some embodiments, the substrate comprises or is composed of GexSi¹-x, wherein 0 ≦ x ≦ 1. For example, in some embodiments, the absorption region comprises or is composed of Ge, and the substrate comprises or is composed of Si.

[0170] In some embodiments, the absorption region is doped with a gradient doping distribution. In some embodiments, the maximum concentration of the gradient doping distribution is higher than the second peak doping concentration of the substrate or low barrier region (e.g., 610 of any of Figures 6A-6E or 7A, 7C-7E). In some embodiments, the minimum concentration of the gradient doping distribution is higher than the second peak doping concentration of the second dopant. In some embodiments, the gradient doping distribution may vary from the first surface of the absorption region or from the second doped region (e.g., 508 of any of Figures 5A-5B, 6A-6E, or 7A-7E) to the second surface of the absorption region. In some embodiments, the gradient doping distribution may increase / decrease gradually or in steps, depending on the carrier movement direction. In some embodiments, the concentration of the gradient doping distribution increases / decreases gradually from the first surface or the second doped region of the absorption region to the second surface of the absorption region, depending on the carrier movement direction. In some embodiments, the concentration of the gradient doping distribution gradually increases / decreases radially from the center of the first or second doped region of the absorption region toward the second surface and laterally, depending on the carrier movement direction. For example, if the absorption region is entirely formed on the substrate, carriers of the first type, such as electrons, move substantially from the first surface to the second surface within the absorption region when the first doped region is n-type. The concentration of the gradient doping distribution of the first dopant (e.g., boron) gradually decreases from the first surface of the absorption region or from the second doped region toward the second surface. In some embodiments, the concentration of the gradient doping distribution gradually increases / decreases laterally from the edge of the first or second doped region toward the side of the absorption region, depending on the photocarrier movement direction.

[0171] In some embodiments, the light detection device of this application further includes an optical element (not shown) on a pixel. In some embodiments, the light detection device of this application further includes N optical elements (not shown) on N pixels. The optical elements focus the incoming optical signal light into the absorption region. In some embodiments, the optical elements are packages or lenses.

[0172] In some embodiments, the p-type dopant includes a group III element. In some embodiments, the p-type dopant is boron. In some embodiments, the n-type dopant includes a group V element. In some embodiments, the n-type dopant is phosphorus.

[0173] In this application, unless otherwise stated, the absorption region is configured to absorb photons with peak wavelengths equal to or greater than 800 nm in an invisible wavelength range, such as 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 optical signals and converts the optical signals into electrical signals. The absorption region can be of any suitable shape, such as, but not limited to, a cylinder or a rectangular prism.

[0174] In this application, unless otherwise stated, the thickness of the absorption region depends on the wavelength of the photon to be detected and the material of the absorption region. In some embodiments, when the absorption region contains germanium and is designed to absorb photons with wavelengths equal to or greater than 800 nm, the thickness of the absorption region is equal to or greater than 0.1 μm. In some embodiments, if the absorption region contains germanium and is designed to absorb photons with wavelengths between 800 nm and 2000 nm, the thickness of the absorption region is between 0.1 μm and 2.5 μm. In some embodiments, the thickness of the absorption region is between 1 μm and 2.5 μm to improve quantum efficiency. In some embodiments, the absorption region may be grown using blanket epitaxy, selective epitaxy, or other suitable techniques.

[0175] In some embodiments, when the incident light enters the absorption region from the second surface of the substrate, the light shield is located on the second surface of the substrate away from the absorption region. In some embodiments, the shape of the optical window may be elliptical, circular, rectangular, square, rhomboid, octagonal, or any other suitable shape as shown in the top view of the optical window.

[0176] In this application, unless otherwise specified, the type of carriers collected by the carrier collection area of ​​one switch is the same as the type of carriers collected by the carrier collection area of ​​another switch within the same pixel. For example, if the photodetector is used to collect electrons, when the first switch is turned on and the second switch is turned off, the carrier collection area in the first switch collects electrons of photocarriers generated by the absorption area, and when the second switch is turned on and the first switch is turned off, the carrier collection area in the second switch also collects electrons of photocarriers generated by the absorption area.

[0177] In this application, unless otherwise stated, the term "electrode" includes metals or alloys. For example, a first electrode, a second electrode, a readout electrode, or a control electrode may comprise an Al, Cu, W, Ti, Ta-TaN-Cu stack, or a Ti-TiN-W stack.

[0178] In this document, terms such as "first," "second," "third," "fourth," and "fifth" may describe various elements, objects, regions, layers, and / or parts, which should not be limited to these terms. These terms may only be used to distinguish different elements, objects, 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. "Light detection," "light sensing," "ray detection," and any other similar terms may be used interchangeably.

[0179] Spatial descriptions, such as "above," "top," and "bottom," etc., unless otherwise specified, are used to indicate orientation with respect to the figures shown. 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.

[0180] In this article, "essence" means that the semiconductor material has not been intentionally doped.

[0181] In this document, unless otherwise defined, terms such as "substantially" and "approximately" are used to describe and indicate minor variations. When used with respect to events or situations, these terms may include instances where the event or situation occurs precisely at the present moment, or instances where the event or situation occurs to a point close to an approximate point. For example, when used with numerical values, these terms may include a range of variation less than or equal to ±10% of the numerical 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%.

[0182] Although the above description is based on preferred embodiments, it should be understood that these preferred embodiments do not constitute a limitation on the present application. On the contrary, the present 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 include all modifications and similar arrangements and processes.

[0183] Those skilled in the art should be able to easily make various modifications and variations to the equipment and methods without departing from the teachings of this application. Accordingly, the interpretation of this application should not be limited to the scope defined in the appended claims.

[0184] While the preferred embodiments of this application have been described above by way of example, it should be understood that this application is not limited thereto. Rather, it is intended to cover various modifications and similar arrangements and programs, and therefore the scope of the claims should be interpreted in the broadest sense to include all such modifications and similar arrangements and programs. [Simplified Explanation of the Diagram]

[0048] The following detailed description, together with the accompanying drawings, will enable the reader to more easily understand and comprehend the above-described features and the many advantages of this application, in which: FIG1A is a top view of an exemplary photodetector device depicted according to one or more embodiments of this application; FIG1B is a cross-sectional view along line A-A' in FIG1A depicted according to one or more embodiments of this application; FIG2A is a top view of an exemplary photodetector device depicted according to one or more embodiments of this application; FIG2B is a cross-sectional view along line A-A' in FIG2A depicted according to one or more embodiments of this application; FIG2C is a cross-sectional view along line A-A' in FIG2A depicted according to one or more embodiments of this application; FIG3A is a top view of an exemplary photodetector device depicted according to one or more embodiments of this application; FIG3B is a cross-sectional view along line A-A' in FIG3A depicted according to one or more embodiments of this application; FIG3C is another top view of the photodetector device in FIG3A depicted according to one or more embodiments of this application; Figure 4A is a top view of a photodetector according to one or more embodiments of the present application; Figure 4B is a cross-sectional view along line A-A' of the photodetector in Figure 4A according to one or more embodiments of the present application; Figure 5A is a cross-sectional view of a photodetector according to one or more embodiments of the present application; Figure 5B is a cross-sectional view of another photodetector according to one or more embodiments of the present application; Figure 6A is a top view of a photodetector according to one or more embodiments of the present application; Figure 6B is a cross-sectional view along line A-A' of the photodetector in Figure 6A according to one or more embodiments of the present application; Figure 6C is a top view of a photodetector according to one or more embodiments of the present application; Figure 6D is a top view of a photodetector according to one or more embodiments of the present application; Figure 6E is a cross-sectional view along line A-A' of the photodetector in Figure 6D according to one or more embodiments of the present application; Figure 7A is a top view of a dual-switch photodetector according to one or more embodiments of the present application. Figure 7B is a cross-sectional view along line A-A' of the dual-switch photodetector in Figure 7A, depicting one or more embodiments of the present application; Figure 7C is a top view of another dual-switch photodetector, depicting one or more embodiments of the present application; Figure 7D is a top view of another dual-switch photodetector, depicting one or more embodiments of the present application; Figure 7E is a top view of a single-switch photodetector, depicting one or more embodiments of the present application; Figures 8A-8C are partial cross-sectional views of a photodetector, depicting one or more embodiments of the present application; Figures 9A-9D are examples of the control area of ​​a photodetector, depicting one or more embodiments of the present application; Figure 10A is a block diagram of an exemplary embodiment of an imaging system; and Figure 10B is a block diagram of an exemplary receiver unit or controller. Similar elements are designated using similar reference numerals and names.

Claims

1. A photodetector comprising: a pixel including an absorption region configured to receive an optical signal and generate photocarriers in response to the optical signal, wherein the absorption region includes a first material; a substrate supporting the absorption region, wherein the substrate includes a second material different from the first material; and at least one additional region formed in the substrate, wherein... The at least one additional region includes a third material different from the second material, wherein the total area of ​​the absorbing region and the at least one additional region is at least 20% of the pixel area; and an isolation region formed in the substrate, the isolation region surrounding the absorbing region and the isolation region being between the absorbing region and the at least one additional region.

2. The light detection device as described in claim 1, wherein, The first material is the same as the third material.

3. The light detection device as described in claim 1, wherein, The third material includes a metal or an insulating material.

4. The light detection device as described in claim 1, wherein, The at least one additional zone includes multiple additional zones arranged around the absorption zone.

5. The light detection device as described in claim 1, wherein, The absorption region is doped with a first dopant belonging to a first conduction type, and the at least one additional region is doped with a second dopant belonging to the first conduction type.

6. The light detection device as claimed in claim 1 further includes a blocking layer surrounding the at least one additional region.

7. A photodetector comprising: two adjacent pixels, each including an absorption region configured to receive an optical signal and generate photocarriers in response to the optical signal, wherein... The absorption region includes a first material; a substrate supporting the two adjacent pixels, wherein the substrate includes a second material different from the first material; at least one additional region, bits between the absorption regions of the two adjacent pixels, wherein the at least one additional region includes a third material different from the second material; and two isolation regions, each surrounding a corresponding absorption region in the absorption regions of the two adjacent pixels, each isolation region being between the corresponding absorption region and the at least one additional region.

8. The light detection device as described in claim 7, wherein, For each of the two adjacent pixels, the total area of ​​the absorption region and the at least one additional region is at least 20% of the pixel area.

9. The light detection device as described in claim 7, wherein, The first material is the same as the third material.

10. The light detection device as described in claim 7, wherein, The third material includes a metal or an insulating material.

11. The light detection device as described in claim 7, wherein, The absorption region is doped with a first dopant belonging to a first conduction type, and the at least one additional region is doped with a second dopant belonging to the first conduction type.

12. An imaging system comprising: a transmitter; a receiver; a signal processor electrically communicating with the receiver; and a controller electrically communicating with the signal processor and the transmitter; wherein, The receiver includes one or more photodetectors, each of which includes: a pixel including an absorption region configured to receive an optical signal and generate photocarriers in response to the optical signal, wherein the absorption region includes a first material; a substrate supporting the absorption region, wherein the substrate includes a second material different from the first material; and at least one additional region formed in the substrate, wherein the at least one additional region includes a third material different from the second material; and an isolation region formed in the substrate, the isolation region surrounding the absorption region and the isolation region being located between the absorption region and the at least one additional region, wherein the total area of ​​the absorption region and the at least one additional region is at least 20% of the pixel area.

13. The imaging system as described in claim 12, wherein, One of the one or more photodetectors further includes an isolation region formed in the substrate, wherein the isolation region surrounds the absorption region and the at least one additional region.

14. The imaging system as described in claim 12, wherein, The first material is the same as the third material.

15. The imaging system as described in claim 12, wherein, The absorption region is doped with a first dopant belonging to a first conduction type, and the at least one additional region is doped with a second dopant belonging to the first conduction type.

Images