Photoelectric detector and preparation method thereof

Abstract

The invention discloses a photoelectric detection device and a preparation method thereof, and the photoelectric detection device comprises a photoelectric detection unit which comprises a multiplication region; the first ohmic contact region and the second ohmic contact region are respectively arranged on two opposite sides of the multiplication region; the expanded charge region, the absorption region and the third ohmic contact region are sequentially stacked on the surface between the two sides of the multiplication region; the width between the two sides of the multiplication region is larger than the width of the charge expansion region in the same direction, and the charge expansion region is used for connecting the absorption region with the multiplication region and limiting the electric field in the multiplication region. The cascaded silicon-based germanium photoelectric detector with high sensitivity and high gain effects can be provided, the problem of poor detection effect caused by large dark current and large noise of a traditional silicon-based germanium photoelectric detector can be solved, and the sensitivity and the performance level of the photoelectric detector are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of optoelectronic devices, and in particular to a photoelectric detection device with high sensitivity and high gain effect and a preparation method thereof. Background Art

[0002] With the continuous development of communication technology, weak light detection in the near-infrared communication band has become a research hotspot. Semiconductor avalanche detectors with high internal gain and external quantum efficiency are considered to be promising semiconductor detection devices for low-loss and high-efficiency weak light detection, and can be widely used in optoelectronic communications, biological detection, chemical analysis and other fields.

[0003] At present, the most widely used photodetectors are III-V materials and silicon-based CMOS devices. Although III-V materials have good absorption coefficients for near-infrared light, they have high material costs and are incompatible with CMOS. Silicon cannot absorb near-infrared light used for telecommunications and data communications due to its low absorption coefficient. Germanium avalanche photodetectors can absorb near-infrared light, but due to the large impact ionization ratio of carriers in germanium, there are problems such as small gain-bandwidth product and high noise.

[0004] Taking advantage of germanium's absorption effect on near-infrared light and silicon's low charge multiplication noise, silicon-germanium avalanche photodetectors with separate absorption and charge multiplication regions not only have good absorption effects on near-infrared light, but are also compatible with CMOS. However, traditional silicon-germanium avalanche photodetectors usually require a large electric field to obtain a large gain in the avalanche region. Due to the lattice mismatch at the germanium-silicon interface, there will be a large number of dislocations in the germanium epitaxial layer, which will induce a large dark current under the action of a large electric field, thus affecting the performance of the detector. Therefore, reducing the problem of poor detection results caused by excessive dark current and high noise is important for improving the sensitivity and detection performance of photodetectors. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned defects in the prior art and to provide a photoelectric detection device and a method for preparing the same.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] The present invention provides a photoelectric detection device, including a photoelectric detection unit, which includes:

[0008] doubling zone;

[0009] A first ohmic contact region and a second ohmic contact region are disposed at opposite sides of the multiplication region;

[0010] An extended charge region, an absorption region and a third ohmic contact region are sequentially stacked on the surface between the two sides of the multiplication region;

[0011] The width between the two sides of the multiplication region is greater than the width of the extended charge region in the same direction, and the extended charge region is used to connect the absorption region with the multiplication region and limit the electric field in the multiplication region.

[0012] Further, the multiplication region is an intrinsic first semiconductor region, the first ohmic contact region is an N-type heavily doped first semiconductor region, the second ohmic contact region is a P-type heavily doped first semiconductor region, the extended charge region is a P-type lightly doped first semiconductor region, the absorption region is an intrinsic second semiconductor region, and the third ohmic contact region is a P-type heavily doped second semiconductor region.

[0013] Furthermore, the first ohmic contact region, the multiplication region and the second ohmic contact region are formed on the intrinsic first semiconductor layer and are arranged in sequence along the surface of the first semiconductor layer to form a dual-electrode avalanche photodiode using a lateral multiplication electric field, and the extended charge region is formed on the surface of the first semiconductor layer on the multiplication region.

[0014] Further, the first semiconductor includes silicon, and / or the second semiconductor includes germanium.

[0015] Furthermore, a first electrode is disposed on the first ohmic contact region, a second electrode is disposed on the second ohmic contact region, and a third electrode is disposed on the third ohmic contact region.

[0016] Furthermore, there are one or more photodetection units; when there are multiple photodetection units, the extended charge regions of each photodetection unit are connected as a whole, the first ohmic contact regions of each photodetection unit are connected, and the second ohmic contact regions of each photodetection unit are connected and grounded, forming a single-pixel photodetection device cascaded with multiple photodetection units.

[0017] Furthermore, the photoelectric detection unit is formed on an SOI substrate, which is provided with a bottom silicon layer, a buried oxide layer and a top silicon layer in sequence, the first ohmic contact region, the multiplication region and the second ohmic contact region are formed on the top silicon layer and are arranged in sequence along the surface of the top silicon layer, and the extended charge region is formed on the surface of the top silicon layer on the multiplication region.

[0018] The present invention also provides a method for preparing a photoelectric detection device, comprising:

[0019] providing a substrate having an intrinsic first semiconductor layer;

[0020] A photodetection unit is formed on the first semiconductor layer, comprising:

[0021] defining a multiplication region on the first semiconductor layer, forming a first ohmic contact region and a second ohmic contact region on both sides of the multiplication region, and forming an extended charge region on the first semiconductor layer within the multiplication region, so that the extended charge region is separated from the first ohmic contact region and the second ohmic contact region;

[0022] An intrinsic second semiconductor layer as an absorption region and a third ohmic contact region are sequentially formed on the extended charge region.

[0023] Further, the substrate comprises an SOI substrate, and the SOI substrate comprises in sequence a bottom silicon layer, a buried oxide layer and a top silicon layer as the intrinsic first semiconductor layer;

[0024] By patterning the surface of the top silicon layer, a protruding extended charge region pattern is formed on the surface of the top silicon layer within the defined multiplication region; by performing P-type lightly doped ion implantation on the extended charge region pattern, the extended charge region is formed; by performing N-type heavily doped ion implantation and P-type heavily doped ion implantation in the top silicon layer on both sides of the multiplication region, the first ohmic contact region and the second ohmic contact region are formed correspondingly;

[0025] forming an intrinsic germanium absorption region by epitaxially growing an intrinsic germanium layer as the intrinsic second semiconductor layer on the surface of the extended charge region;

[0026] The third ohmic contact region is formed by performing P-type heavy doping ion implantation on the surface of the intrinsic germanium absorption region;

[0027] Leading out and controlling are performed by forming a first electrode on the first ohmic contact region, forming a second electrode on the second ohmic contact region, and forming a third electrode on the third ohmic contact region.

[0028] Further, it includes forming one or more photodetection units on the first semiconductor layer; when a plurality of photodetection units are formed, the extended charge regions of each photodetection unit are connected as a whole, and the first ohmic contact regions of each photodetection unit are connected through the first electrode, and the second ohmic contact regions of each photodetection unit are connected through the second electrode and grounded to form a single-pixel photodetection device cascaded with a plurality of photodetection units.

[0029] It can be seen from the above technical scheme that the present invention can form a three-electrode avalanche photodetector device by forming a photodetection unit with a double-electrode (first ohmic contact area, second ohmic contact area) avalanche photodiode with a transverse multiplication electric field and an absorption area with an electrode (third ohmic contact area); at the same time, by increasing the width of the multiplication area, the edge electric field effect of the device can be effectively reduced. In addition, by setting an extended charge area between the absorption area and the multiplication area, the internal electric field of the multiplication area can be limited, and the electric field in the absorption area can be reduced, thereby eliminating the impact ionization effect of the absorption area, and at the same time, it can prevent the absorption area material (germanium) from diffusing to the gain area and affecting the detector performance. In addition, by connecting the extended charge layers of multiple photodetection units to each other as a whole, a single-pixel photodetection device cascaded with multiple photodetection units is formed, which can form a photodetection device with a multiplication effect and avoid the problem of excessive dark current caused by the excessive area of ​​a single photodetection unit. Therefore, the present invention can provide a cascaded silicon-germanium photodetector device with high sensitivity and high gain effect, and can solve the problem of poor detection effect caused by large dark current and high noise in traditional silicon-germanium photodetectors, thereby improving the sensitivity and performance level of the photodetector device. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1-Figure 2 The figure is a schematic structural diagram of a photoelectric detection device according to a preferred embodiment of the present invention.

[0031] Figure 3-Figure 8 The figure is a schematic diagram of the process steps of a method for preparing a photoelectric detection device according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with general skills in the field to which the present invention belongs. "Including" and similar words used in this article mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0033] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0034] refer to Figure 1A photodetection device of the present invention includes a photodetection unit 10. The photodetection unit 10 includes a multiplication region 21, an extended charge region 15, an absorption region 16, a first ohmic contact region 13, a second ohmic contact region 20, and a third ohmic contact region 17.

[0035] The first ohmic contact region 13 and the second ohmic contact region 20 are disposed on two opposite sides of the multiplication region 21 , such as the left and right sides of the multiplication region 21 as shown in the figure.

[0036] The extended charge region 15, the absorption region 16 and the third ohmic contact region 17 are sequentially stacked on the upper surface of the multiplication region 21 along the vertical direction away from the surface of the multiplication region 21, and are located between the two sides of the multiplication region 21, that is, the extended charge region 15, the absorption region 16 and the third ohmic contact region 17 are located on the upper surface of the multiplication region 21 between the first ohmic contact region 13 and the second ohmic contact region 20. In addition, the lateral width of the multiplication region 21, that is, the width between the left and right sides of the multiplication region 21 (that is, the distance between the first ohmic contact region 13 and the second ohmic contact region 20) is greater than the width of the extended charge region 15 (including the absorption region 16 and the third ohmic contact region 17) in the same direction (lateral direction). By increasing the size of the multiplication region 21 here, the edge electric field effect can be eliminated to prevent the device from being broken down prematurely.

[0037] The extended charge region 15 is used to connect the absorption region 16 with the multiplication region 21 and to limit the electric field in the multiplication region 21 .

[0038] refer to Figure 1 In some embodiments, the multiplication region 21 is an intrinsic first semiconductor region, that is, the material of the multiplication region 21 is an intrinsic first semiconductor.

[0039] The first ohmic contact region 13 is an N+ type heavily doped first semiconductor region, that is, the first ohmic contact region 13 is formed by heavily doping the first semiconductor material with N+ type.

[0040] The second ohmic contact region 20 is a P+ type heavily doped first semiconductor region, that is, the second ohmic contact region 20 is formed by heavily doping the first semiconductor material with P+ type.

[0041] The extended charge region 15 is a P-type lightly doped first semiconductor region, that is, the extended charge region 15 is formed by lightly doping the first semiconductor material with P-type.

[0042] The absorption region 16 is an intrinsic second semiconductor region, that is, the material of the absorption region 16 is an intrinsic second semiconductor.

[0043] The third ohmic contact region 17 is a P+ type heavily doped second semiconductor region, that is, the third ohmic contact region 17 is formed by heavily doping the second semiconductor material with P+ type.

[0044] refer to Figure 1 In some embodiments, the photodetection unit 10 is formed on the intrinsic first semiconductor layer 12. Specifically, the first ohmic contact region 13, the multiplication region 21, and the second ohmic contact region 20 are formed on the intrinsic first semiconductor layer 12, and are sequentially arranged along the upper surface direction of the first semiconductor layer 12. The extended charge region 15 protrudes from the upper surface of the first semiconductor layer 12 on the multiplication region 21, and is separated from the first ohmic contact region 13 and the second ohmic contact region 20 on both sides by a certain distance.

[0045] Furthermore, the first semiconductor layer 12 is located on the dielectric layer 11 to isolate the photoelectric detection unit 10 .

[0046] In some embodiments, the material of the first semiconductor layer 12 is an intrinsic first semiconductor. The intrinsic first semiconductor includes intrinsic silicon (i-Si). The second semiconductor includes germanium (Ge). The material of the dielectric layer 11 includes silicon dioxide (SiO2).

[0047] In some embodiments, a first electrode 14 is disposed on the first ohmic contact region 13, a second electrode 19 is disposed on the second ohmic contact region 20, and a third electrode 18 is disposed on the third ohmic contact region 17 for electrically leading out the photodetection unit 10. The first electrode 14 to the third electrode 18 may be made of aluminum.

[0048] In this way, the N+ first ohmic contact region 13, the silicon multiplication region 21 and the P+ second ohmic contact region 20 arranged on the silicon first semiconductor layer 12 form a two-electrode silicon avalanche photodiode using a lateral multiplication electric field, and together with the germanium absorption region 16 connected through the P-extended charge region 15, form a three-electrode (including the first ohmic contact region 13 to the third ohmic contact region 17 of each electrode) silicon-based germanium avalanche photodetector device. Among them, the two-electrode silicon avalanche photodiode has the effect of low dark current and high gain, the germanium absorption region 16 is used to provide light-induced charges, and the absorption region 16 and the multiplication region 21 are connected through the P-type lightly doped extended charge region 15, and the P-type lightly doped extended charge region 15 can be used to limit the electric field in the silicon multiplication region 21.

[0049] In some embodiments, the photodetection unit 10 is formed on an SOI substrate 100. The SOI substrate 100 is provided with a bottom silicon layer (not shown), a buried oxide layer 101 and a top silicon layer 102 in order from bottom to top. Among them, the buried oxide layer 101 is used as the above-mentioned dielectric layer 11, and the top silicon layer 102 is used as the silicon first semiconductor layer 12. Thus, the first ohmic contact region 13, the multiplication region 21 and the second ohmic contact region 20 are formed on the top silicon layer 102, and are arranged in order along the upper surface of the top silicon layer 102; the extended charge region 15 is formed on the upper surface of the top silicon layer 102 on the multiplication region 21, and is higher than the upper surface of the top silicon layer 102 where the first ohmic contact region 13 and the second ohmic contact region 20 are located.

[0050] In some embodiments, the photodetection device includes one photodetection unit 10. Further, one photodetection unit 10 (photodetection device) occupies an area of ​​1 pixel.

[0051] refer to Figure 2 . In some embodiments, the photodetection device includes a plurality of photodetection units 10. Each photodetection unit 10 is arranged in parallel on the SOI substrate 100; and, the extended charge region 15 of each photodetection unit 10 is connected as a whole, and the germanium absorption region 16 of each photodetection unit 10 (and the third ohmic contact region 17 and the third electrode 18 (not shown) thereon) are separately arranged on the common extended charge region 15. At the same time, the N+ first ohmic contact regions 13 (not shown) of each photodetection unit 10 are connected together through the first electrode 14, and the P+ second ohmic contact regions 20 of each photodetection unit 10 are connected together and grounded through the second electrode 19 (not shown), forming a single-pixel photodetection device cascaded with multiple photodetection units 10, that is, all the photodetection units 10 in one photodetection device jointly occupy the area of ​​1 pixel.

[0052] In one example, two photodetection units 10 can be used to form a photodetection device of the present invention, which can improve the effective receiving area of ​​the device on the basis of ensuring the dark current of the device in a limited space. In addition, multiple photodetection units 10 of the present invention can be arranged in an array form. Alternatively, the photodetection device of the present invention can be used to form a photodetector array.

[0053] In some embodiments, the N+ first ohmic contact regions 13 of any two adjacent photodetection units 10 are merged into one and disposed on the first semiconductor layer 12 (top silicon layer 102) on one side of the multiplication region 21 between the two photodetection units 10. At the same time, the P+ second ohmic contact regions 20 of any two adjacent photodetection units 10 are also merged into one and disposed on the first semiconductor layer 12 (top silicon layer 102) on the other side of the multiplication region 21 between the two photodetection units 10. In this way, the distance between the N+ first ohmic contact region 13 and the germanium absorption region 16 in each photodetection unit 10 can be further increased, thereby more effectively eliminating the edge electric field effect and preventing the device from being broken down prematurely.

[0054] Principle description: The sensitivity of silicon-based germanium avalanche photodetector devices can be improved mainly by two aspects: one is to reduce the dark current of the device; the other is to reduce the k (ionization coefficient ratio) value of the device material. The present invention forms an extended charge region 15 by doping P-type impurities in the silicon on the multiplication region 21, so that the three-electrode silicon-based germanium avalanche photodetector device can have the effect of low dark current and high sensitivity. This is because silicon has a very low k value (0.02) and has good dark current and multiplication characteristics; and by setting the P-type extended charge region 15, the electric field inside the silicon multiplication region 21 can be limited, and the electric field in the germanium absorption region 16 can be reduced, thereby eliminating the impact ionization of germanium, and at the same time, the mutual diffusion between silicon and germanium can be reduced, preventing germanium from diffusing to the gain region so that the k value of the multiplication region 21 increases and affects the detector performance.

[0055] At the same time, the area of ​​the silicon germanium avalanche photodetector is proportional to the dark current of the device. As the area of ​​the photodetector increases, its dark current also increases. Therefore, the avalanche photodetector cannot maintain a large detection area, and it is necessary to reduce the detection area to ensure the dark current of the device to ensure that it is not broken down. However, the improvement of the detection accuracy of the photodetector depends on a large effective detection area. Therefore, how to increase the effective detection area while ensuring the dark current has an important impact on the improvement of the sensitivity of the avalanche photodetector. The present invention forms a photodetector device with a multiplication effect by connecting the extended charge regions 15 of multiple photodetection units 10 to form a cascade of multiple photodetection units 10, thereby avoiding the problem of excessive dark current caused by the large area of ​​a single detector. The electrodes on the N+ first ohmic contact region 13 and the P+ second ohmic contact region 20 of each photodetection unit 10 can be connected in parallel to apply a bias voltage to control the electric field of the silicon multiplication region 21; a voltage is applied to the third electrode 18 of the germanium absorption region 16 to achieve the current output characteristics of the control device (the second electrode 19 on the P+ second ohmic contact region 20 should be grounded after being connected in parallel).

[0056] A method for preparing a photoelectric detection device of the present invention is further described in detail below through specific implementation modes and in conjunction with the accompanying drawings.

[0057] refer to Figure 3-Figure 8 The photoelectric detection device manufacturing method of the present invention can be used to manufacture, for example Figure 1 or Figure 2 A photoelectric detection device may include the following steps:

[0058] Step S1: providing a substrate having an intrinsic first semiconductor layer 12 .

[0059] like Figure 3 As shown, a SOI substrate 100 is used to prepare a photoelectric detection device of the present invention. The SOI substrate 100 includes a bottom silicon layer (not shown), a buried oxide layer 101 (SiO2) and a top silicon layer 102 (i-Si) from bottom to top. Among them, the top silicon layer 102 of intrinsic silicon material located on the surface of the SOI substrate 100 is used as the intrinsic first semiconductor layer 12.

[0060] Step S2 : forming an extended charge region 15 and an avalanche photodiode on the first semiconductor layer 12 .

[0061] like Figure 3 As shown, first, on the top silicon layer 102 of the SOI substrate 100 as the intrinsic first semiconductor layer 12, the area 151 occupied by the extended charge region is defined by photolithography (i.e., the photoresist pattern, and removed after the extended charge region 15 is formed), so as to further prepare the device structures of the photodetection unit 10 on the top silicon layer 102, including the preparation of the extended charge region 15, the first ohmic contact region 13, the second ohmic contact region 20, the multiplication region 21, and the absorption region 16 and the third ohmic contact region 17, etc. The following is a detailed description of the formation of a photodetection unit 10 as an example.

[0062] like Figure 4 As shown, the surface of the top silicon layer 102 outside the defined extended charge region occupied region 151 is etched through an etching process, and a protruding extended charge region pattern 152 is formed on the surface of the top silicon layer 102 in the defined extended charge region occupied region 151. Thus, a new exposed surface of the top silicon layer 102 is formed outside the extended charge region pattern 152.

[0063] like Figure 5 As shown, then, by an ion implantation process, P-type lightly doped ions are implanted into the extended charge region pattern 152, so that the extended charge region pattern 152 located on the defined multiplication region occupied region 211 is formed into a P-silicon extended charge region 15 (P-Si). The thickness of the formed P-silicon extended charge region 15 is 80 to 120 nm, preferably about 100 nm.

[0064] Next, by photolithography, the area 211 occupied by the multiplication region is defined on the surface of the top silicon layer 102 (i.e., the photoresist pattern, which is removed after the first ohmic contact region 13 and the second ohmic contact region 20 are formed), the extended charge region 15 is included, and the boundary of the defined area 211 occupied by the multiplication region is kept at a certain distance from the boundary of the extended charge region 15. Then, by ion implantation, from the exposed surface of the top silicon layer 102 downward, N+ type heavily doped ion implantation and P+ type heavily doped ion implantation are respectively performed in the top silicon layer 102 on the left and right sides of the area 211 occupied by the defined multiplication region. Thus, the N+ first ohmic contact region 13 and the P+ second ohmic contact region 20 are correspondingly formed below the surface of the top silicon layer 102 on the left and right sides of the area 211 occupied by the defined multiplication region, as electrodes of the silicon avalanche photodetector device.

[0065] In this way, a lateral intrinsic silicon multiplication region 21 is formed between the first ohmic contact region 13 and the second ohmic contact region 20, and a dual-electrode avalanche photodiode structure using a lateral multiplication electric field is formed by the N+ first ohmic contact region 13, the intrinsic silicon multiplication region 21 and the P+ second ohmic contact region 20. In addition, by increasing the lateral width of the formed multiplication region 21, the extended charge region 15 is separated from the first ohmic contact region 13 and the second ohmic contact region 20.

[0066] Step S3 : forming an absorption region 16 on the extended charge region 15 .

[0067] like Figure 6 As shown, an intrinsic germanium layer is formed as an intrinsic second semiconductor layer on the upper surface of the extended charge region 15 through an epitaxial process, thereby forming an intrinsic germanium absorption region 16 connected to the intrinsic silicon multiplication region 21 through the P-silicon extended charge region 15.

[0068] like Figure 7 As shown, then, by an ion implantation process, P+ heavily doped ions are implanted into the upper surface of the germanium absorption region 16, thereby forming a third ohmic contact region 17 of P+ heavily doped germanium on the upper surface of the germanium absorption region 16, which serves as a contact layer of the germanium absorption region 16 of the detection device.

[0069] When preparing the germanium absorption region 16 , the germanium material can be grown on the determined extended charge region 15 by an epitaxial process using a high-low temperature two-step method, and the excess germanium film can be removed by thinning technology to form the germanium absorption region 16 .

[0070] Step S4 : forming an extraction electrode on the avalanche photodiode and the absorption region 16 .

[0071] like Figure 8As shown, finally, an aluminum first electrode 14 is formed on the first ohmic contact region 13 , an aluminum second electrode 19 is formed on the second ohmic contact region 20 , and an aluminum third electrode 18 is formed on the third ohmic contact region 17 to perform lead-out and control from the first ohmic contact region 13 to the third ohmic contact region 17 .

[0072] If the preparation is e.g. Figure 2 The multiple cascaded photodetection units 10 shown can integrate the extended charge regions 15 of each photodetection unit 10 into an overall region when defining the extended charge region 15, and form a total extended charge region 15 of an overall structure located on the multiplication region 21 of each photodetection unit 10 on the top silicon layer 102 through patterning and ion implantation, so that the extended charge regions 15 of each photodetection unit 10 are connected as a whole. However, the germanium absorption region 16 and the third ohmic contact region 17 of each photodetection unit 10 are still formed separately.

[0073] At the same time, you can Figure 2 As shown, a lead-out structure is formed so that two adjacent photodetection units 10 share the same N+ first ohmic contact region 13 and P+ second ohmic contact region 20, or a lead-out structure is formed so that each photodetection unit 10 uses a separate N+ first ohmic contact region 13 and P+ second ohmic contact region 20.

[0074] In addition, when forming the lead-out electrodes (first electrode 14, second electrode 19) of multiple photodetection units 10, the first ohmic contact area 13 of each photodetection unit 10 can be jointly led out by connecting with the first electrode 14, and the second ohmic contact area 20 of each photodetection unit 10 can be jointly grounded by connecting with the second electrode 19, thereby forming a single-pixel photodetection device with multiple photodetection units 10 cascaded.

[0075] In summary, the present invention forms a photodetection unit 10 by using a double-electrode (first ohmic contact region 13, second ohmic contact region 20) avalanche photodiode with a transverse multiplication electric field and an absorption region 16 with an electrode (third ohmic contact region 17), which can form a three-electrode avalanche photodetection device; at the same time, by increasing the width of the multiplication region 21, the edge electric field effect of the device can be effectively reduced. In addition, by setting an extended charge region 15 between the absorption region 16 and the multiplication region 21, the internal electric field of the multiplication region 21 can be limited, and the electric field in the absorption region 16 can be reduced, thereby eliminating the impact ionization effect of the absorption region 16, and at the same time, the absorption region 16 material (germanium) can be prevented from diffusing to the gain region and affecting the detector performance. In addition, by connecting the extended charge layers of multiple photodetection units 10 to each other as a whole, a single-pixel photodetection device cascaded with multiple photodetection units 10 is formed, which can form a photodetection device with a multiplication effect, and avoid the problem of excessive dark current caused by the excessive area of ​​a single photodetection unit 10. Therefore, the present invention can provide a cascaded silicon-germanium photodetector device with high sensitivity and high gain effect, and can solve the problem of poor detection effect caused by large dark current and high noise in traditional silicon-germanium photodetectors, thereby improving the sensitivity and performance level of the photodetector device.

[0076] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.

Claims

1. A photoelectric detection device, characterized in that: A photoelectric detection unit is included, which includes: doubling zone; A first ohmic contact region and a second ohmic contact region are disposed at opposite sides of the multiplication region; An extended charge region, an absorption region and a third ohmic contact region are sequentially stacked on the surface between the two sides of the multiplication region; The width between the two sides of the multiplication region is greater than the width of the extended charge region in the same direction, and the extended charge region is used to connect the absorption region with the multiplication region and limit the electric field in the multiplication region.

2. The photoelectric detection device according to claim 1, characterized in that: The multiplication region is an intrinsic first semiconductor region, the first ohmic contact region is an N-type heavily doped first semiconductor region, the second ohmic contact region is a P-type heavily doped first semiconductor region, the extended charge region is a P-type lightly doped first semiconductor region, the absorption region is an intrinsic second semiconductor region, and the third ohmic contact region is a P-type heavily doped second semiconductor region.

3. The photoelectric detection device according to claim 2, characterized in that: The first ohmic contact region, the multiplication region and the second ohmic contact region are formed on an intrinsic first semiconductor layer and are arranged in sequence along the surface of the first semiconductor layer to form a dual-electrode avalanche photodiode using a lateral multiplication electric field, and the extended charge region is formed on the surface of the first semiconductor layer on the multiplication region.

4. The photoelectric detection device according to claim 2, characterized in that: The first semiconductor includes silicon, and / or the second semiconductor includes germanium.

5. The photoelectric detection device according to claim 1, characterized in that: A first electrode is disposed on the first ohmic contact region, a second electrode is disposed on the second ohmic contact region, and a third electrode is disposed on the third ohmic contact region.

6. The photoelectric detection device according to claim 1, characterized in that: There are one or more photodetection units; when there are multiple photodetection units, the extended charge regions of each photodetection unit are connected as a whole, the first ohmic contact regions of each photodetection unit are connected, and the second ohmic contact regions of each photodetection unit are connected and grounded, forming a single-pixel photodetection device cascaded with multiple photodetection units.

7. The photoelectric detection device according to claim 6, characterized in that: The photoelectric detection unit is formed on an SOI substrate, which is provided with a bottom silicon layer, a buried oxide layer and a top silicon layer in sequence. The first ohmic contact region, the multiplication region and the second ohmic contact region are formed on the top silicon layer and are arranged in sequence along the surface of the top silicon layer. The extended charge region is formed on the surface of the top silicon layer on the multiplication region.

8. A method for preparing a photoelectric detection device, characterized in that: include: providing a substrate having an intrinsic first semiconductor layer; A photodetection unit is formed on the first semiconductor layer, comprising: defining a multiplication region on the first semiconductor layer, forming a first ohmic contact region and a second ohmic contact region on both sides of the multiplication region, and forming an extended charge region on the first semiconductor layer within the multiplication region, so that the extended charge region is separated from the first ohmic contact region and the second ohmic contact region; An intrinsic second semiconductor layer as an absorption region and a third ohmic contact region are sequentially formed on the extended charge region.

9. The method for preparing a photoelectric detection device according to claim 8, characterized in that: The substrate comprises an SOI substrate, and the SOI substrate comprises in sequence a bottom silicon layer, a buried oxide layer and a top silicon layer as the intrinsic first semiconductor layer; By patterning the surface of the top silicon layer, a protruding extended charge region pattern is formed on the surface of the top silicon layer within the defined multiplication region; by performing P-type lightly doped ion implantation on the extended charge region pattern, the extended charge region is formed; by performing N-type heavily doped ion implantation and P-type heavily doped ion implantation in the top silicon layer on both sides of the multiplication region, the first ohmic contact region and the second ohmic contact region are formed correspondingly; forming an intrinsic germanium absorption region by epitaxially growing an intrinsic germanium layer as the intrinsic second semiconductor layer on the surface of the extended charge region; The third ohmic contact region is formed by performing P-type heavy doping ion implantation on the surface of the intrinsic germanium absorption region; Leading out and controlling are performed by forming a first electrode on the first ohmic contact region, forming a second electrode on the second ohmic contact region, and forming a third electrode on the third ohmic contact region.

10. The method for preparing a photoelectric detection device according to claim 9, characterized in that: It includes forming one or more photodetection units on the first semiconductor layer; when forming multiple photodetection units, the extended charge regions of each photodetection unit are connected as a whole, and the first ohmic contact regions of each photodetection unit are connected through the first electrode, and the second ohmic contact regions of each photodetection unit are connected and grounded through the second electrode to form a single-pixel photodetection device cascaded with multiple photodetection units.

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