A Pocket-doped 4H-SiC-based avalanche photodiode device

Abstract

The present invention discloses a pocket-doped 4H-SiC-based avalanche photodiode device, comprising a substrate layer, a multiplication layer, a passivation layer, a PAD layer, a metal electrode region, and a photosensitive window region. By introducing a highly doped pocket region into the multiplication layer of the 4H-SiC avalanche photodiode, the electric field distribution at the edge of the multiplication layer's convex mesas is optimized, reducing the probability of mesa breakdown and increasing the available carrier concentration in the multiplication region. This increases the photocurrent while maintaining a low dark current, raising the device's threshold voltage, current gain, and signal-to-noise ratio, resulting in excellent photoelectric amplification performance.

Description

Technical Field

[0001] The present invention belongs to the field of wide bandgap semiconductor devices, and in particular relates to a pocket-doped 4H-SiC-based avalanche photodiode device. Background Art

[0002] Sunlight is the primary source of ultraviolet radiation at the Earth's surface. The intensity of solar background radiation in the 240-280nm band is virtually zero, creating the "solar-blind" ultraviolet band. Because radiation in this band is evenly distributed throughout the atmosphere, ultraviolet detectors have broad potential applications in ultraviolet communications, ultraviolet warning systems, and other ultraviolet detection technologies. Semiconductor ultraviolet photodetectors are semiconductor sensors based on the photoelectric effect.

[0003] Existing optoelectronic devices can be divided into vacuum and solid-state types based on their structure. Vacuum photomultiplier tubes (PMTs) are currently widely used in industry. For example, the commercial UV PMT model R6836 from Hamamatsu Corporation in Japan has a spectral response range of 115 to 320 nm, a dark current of the order of 0.1 nA, and a photocurrent gain greater than 105. Solid-state avalanche photodiodes (APDs), with lower dark current and greater photocurrent gain, overcome the shortcomings of PMTs, such as large size, fragility, short lifespan, operating voltages exceeding 1000 V, and quantum efficiencies below 30%. They also offer higher sensitivity detection and present broad application prospects.

[0004] Existing Si-based APDs are difficult to meet the requirements of biochemical detection, corona detection, and missile warning, where the radiation intensity is lower than pW / cm 2 Because SiC materials have a wider bandgap and higher thermal stability, and the developed 4H-SiC-based APD has single-photon detection capabilities, it has unique advantages in the field of low-intensity signal detection in extreme environments.

[0005] However, due to the limitations of APD device structure design and process conditions, the existing 4H-SiC APD still has shortcomings such as large table edge electric field and easy breakdown, uneven avalanche breakdown, small device fill factor, low single-photon detection efficiency, and high dark count value. It is necessary to optimize the structural design to improve the device's service stability and enhance its performance indicators. Summary of the Invention

[0006] The object of the present invention is to provide a pocket-doped 4H-SiC-based avalanche photodiode device to address the deficiencies of the prior art.

[0007] The object of the present invention is achieved through the following technical solutions: A pocket-doped 4H-SiC-based avalanche photodiode device, comprising: a substrate layer, a multiplication layer, a passivation layer, a PAD layer, a metal electrode region and a photosensitive window region;

[0008] The substrate layer is cylindrical and is located at the bottom layer of the pocket-doped 4H-SiC-based avalanche photodiode device;

[0009] The multiplication layer is in the form of a convex truncated cone, shares a common central axis with the substrate layer, and contacts the substrate layer along a first direction, wherein the first direction is the central axis of the substrate layer upwards;

[0010] The multiplication layer is divided into five multiplication zones along the first direction, namely the first multiplication zone, the second multiplication zone, the third multiplication zone, the fourth multiplication zone and the fifth multiplication zone. The five multiplication zones share a central axis along the first direction and are in contact with each other in sequence. The first multiplication zone is in the form of a convex frustum, and the second, third, fourth and fifth multiplication zones are in the form of frustum. The frustum of the first multiplication zone, the second, third, fourth and fifth multiplication zones have the same inclination angle.

[0011] The contact surfaces between the substrate layer and the first, second, third, fourth and fifth multiplication regions are all circular surfaces whose outer normals are along the first direction;

[0012] The passivation layer is a hollow truncated cone shell, having a common central axis with the multiplication layer and in contact with its upper surface, covering the outer surface of the multiplication layer, and the contact surface is a fan-shaped surface with the same inclination angle as the truncated cone of the multiplication layer;

[0013] The PAD layer is a hollow truncated cone shell, having a common central axis with the passivation layer and in contact with its upper surface, covering the outer surface of the passivation layer, and the contact surface is a fan-shaped surface with the same inclination angle as the truncated cone of the passivation layer;

[0014] The photosensitive window area is annular and is located on the upper surface of the fifth multiplication zone;

[0015] The metal electrode area includes an anode area and a cathode area, wherein the anode area is a cylindrical ring body, contacts the first multiplication area along the first direction, covers the upper surface of the convex cone of the first multiplication area, and the contact surface is a circular ring; the cathode area is a cylinder, shares the same central axis with the photosensitive window area and contacts along the first direction, covers the photosensitive window area, and the contact surface is a circle.

[0016] Furthermore, the substrate layer and the multiplication layer are made of the same material.

[0017] Furthermore, the band gap of the multiplication layer is greater than the band gap of the substrate layer.

[0018] Furthermore, the first multiplication region and the other multiplication regions have different doping types; the substrate layer, the second multiplication region, the third multiplication region, the fourth multiplication region and the fifth multiplication region have the same doping type.

[0019] Furthermore, the doping concentration of the third multiplication region is higher than that of the second multiplication region and the fourth multiplication region, and the second multiplication region, the third multiplication region and the fourth multiplication region adopt pocket doping.

[0020] The beneficial effects of the present invention are as follows: by introducing a Pocket high-doping region into the multiplication layer of a 4H-SiC avalanche photodiode, the electric field distribution at the edge of the convex table of the multiplication layer is optimized, the table breakdown probability is reduced, the available carrier concentration in the multiplication region is increased, the photocurrent is increased while maintaining a low dark current, the threshold voltage of the device is increased, the current gain and the signal-to-noise ratio are increased, and good photoelectric amplification performance is exhibited. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the structure of a pocket-doped 4H-SiC-based avalanche photodiode device along a first direction;

[0022] Figure 2 The following is a process flow chart for preparing a pocket-doped 4H-SiC-based avalanche photodiode device;

[0023] Figure 3 is a schematic diagram of doping concentration, where Figure 3 (a) is a schematic diagram of the doping concentration of a 4H-SiC APD device along the first direction in Comparative Example 1; Figure 3 (b) is a schematic diagram of the doping concentration of the structure of the pocket-doped 4H-SiC-based avalanche photodiode device along the first direction in Example 2;

[0024] Figure 4 is the volt-ampere characteristic curve, where Figure 4 (a) is the forward volt-ampere characteristic curve, Figure 4 (b) is the reverse volt-ampere characteristic curve;

[0025] Figure 5 is the current gain curve under 280nm monochromatic light;

[0026] Figure 6 The response spectrum is in the ultraviolet and visible light range of 200-450nm. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to illustrate the present invention, rather than to represent all embodiments. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0028] The present invention provides a pocket-doped 4H-SiC-based avalanche photodiode device, comprising a substrate layer, a multiplication layer, a passivation layer, a PAD layer, a metal electrode region and a photosensitive window region.

[0029] The substrate layer is cylindrical and is located at the bottom layer of the pocket-doped 4H-SiC-based avalanche photodiode device.

[0030] The multiplication layer is in the form of a convex frustum, shares a common central axis with the substrate layer, and contacts the substrate layer along a first direction, where the first direction is from the central axis of the substrate layer upward.

[0031] The multiplication layer is divided into five multiplication zones along a first direction, designated as the first, second, third, fourth, and fifth multiplication zones. These five multiplication zones share a common central axis and are sequentially contacted along the first direction. The first multiplication zone is convexly truncated, while the second, third, fourth, and fifth multiplication zones are truncated. The truncated cone portion of the first multiplication zone, the second, third, fourth, and fifth multiplication zones have the same inclination angle.

[0032] The contact surfaces between the substrate layer and the first, second, third, fourth and fifth multiplication regions are all circular surfaces whose outer normals are along the first direction.

[0033] The passivation layer is a hollow truncated cone shell, which has the same central axis as the multiplication layer and contacts with its upper surface, covering the outer surface of the multiplication layer. The contact surface is a fan-shaped surface with the same inclination angle as the truncated cone of the multiplication layer.

[0034] The PAD layer is a hollow truncated cone shell, sharing the same central axis with the passivation layer and contacting its upper surface, covering the outer surface of the passivation layer, and the contact surface is a fan-shaped surface with the same inclination angle as the truncated cone of the passivation layer.

[0035] The photosensitive window area is annular and is located on the upper surface of the fifth multiplication zone.

[0036] The metal electrode region includes an anode region and a cathode region. The anode region is a cylindrical ring, contacting the first multiplication region along a first direction and covering the upper surface of the convex truncated cone of the first multiplication region, with a circular contact surface. The cathode region is a cylindrical body, sharing a central axis with the photosensitive window region and contacting the photosensitive window region along a first direction, covering the photosensitive window region, and having a circular contact surface.

[0037] The substrate layer and the multiplication layer are made of the same material.

[0038] The band gap of the multiplication layer is greater than the band gap of the substrate layer.

[0039] The first multiplication region has a different doping type from the other multiplication regions, and the substrate layer, the second multiplication region, the third multiplication region, the fourth multiplication region, and the fifth multiplication region have the same doping type.

[0040] The doping concentration of the third multiplication region is higher than that of the second multiplication region and the fourth multiplication region, and the second multiplication region, the third multiplication region and the fourth multiplication region adopt pocket doping.

[0041] Example 1

[0042] Figure 1 This is a schematic diagram of the structure of a pocket-doped 4H-SiC-based avalanche photodiode device along the first direction.

[0043] like Figure 1 As shown, a pocket-doped 4H-SiC-based avalanche photodiode device includes: a substrate layer 101, a multiplication layer, a passivation layer 107, a PAD layer 108, a metal electrode region 109 and a photosensitive window region.

[0044] In this embodiment, the materials of the substrate layer 101 and the multiplication layer are both 4H-SiC. The material of the passivation layer 107 is SiN x The PAD layer 108 is a high-quality metal conductive material, and the metal electrode region 109 is a metal contact electrode.

[0045] The n-type doping uniformly adopts the element nitrogen, and the p-type doping uniformly adopts the element aluminum.

[0046] The device is grown on the substrate layer 101 by using a chemical vapor deposition (CVD) method, and the doping concentration of each layer at a specified depth is achieved by using ion implantation.

[0047] The substrate layer 101 is uniformly doped with n-type and is located at the bottom of the pocket-doped 4H-SiC-based avalanche photodiode device with a doping concentration of 1*10 19 cm -3The axis is along the 0001 crystal direction of 4H-SiC, that is, the first direction with the central axis of the cylinder of the substrate layer 101 upward; the substrate layer 101 is cylindrical with a thickness of 10 μm and a bottom diameter of 1000 μm.

[0048] The multiplication layer is in the form of a convex frustum, growing over the substrate layer 101 , sharing a common central axis with the substrate layer 101 , and in contact with the substrate layer 101 along a first direction, where the first direction is the central axis of the substrate layer 101 upward.

[0049] The multiplication layer is divided into five multiplication zones along the first direction, which are respectively recorded as the first multiplication zone 102, the second multiplication zone 103, the third multiplication zone 104, the fourth multiplication zone 105 and the fifth multiplication zone 106. The five multiplication zones share a common central axis along the first direction and are in contact with each other in sequence; the first multiplication zone 102 is a convex frustum, and the second multiplication zone 103, the third multiplication zone 104, the fourth multiplication zone 105 and the fifth multiplication zone 106 are frustum; the inclination angles of the first multiplication zone 102, the second multiplication zone 103, the third multiplication zone 104, the fourth multiplication zone 105 and the fifth multiplication zone 106 are consistent.

[0050] The first multiplication zone 102 is in the shape of a convex truncated cone with an inclination angle of 6 to 10 degrees and a thickness of 3.0 μm; the second multiplication zone 103, the third multiplication zone 104, the fourth multiplication zone 105 and the fifth multiplication zone 106 are respectively in the shape of a truncated cone with an inclination angle of 6 to 10 degrees, a thickness between 0.1 and 0.5 μm, and a diameter of the truncated cone surface of 800 μm.

[0051] The first multiplication region 102 is p-type doped, with a doping concentration between 1*10 15 ~1*10 19 cm -3 The second multiplication region 103, the third multiplication region 104 and the fourth multiplication region 105 are n-type doped, using Pocket high doping, with a doping concentration between 1*10 15 ~5*10 18 cm -3 The five-fold increase region 106 is n-type doped, with a doping concentration of 1*10 19 cm -3 .

[0052] The contact surfaces between the substrate layer 101 and the first multiplication region 102 , the second multiplication region 103 , the third multiplication region 104 , the fourth multiplication region 105 and the fifth multiplication region 106 are all circular surfaces whose outer normals are along the first direction.

[0053] The passivation layer 107 covers the upper surface of the multiplication layer and is in the shape of a hollow truncated cone shell with an inclination angle of 6 to 10 degrees and a thickness of 400 to 600 nm.

[0054] The passivation layer 107 is a hollow truncated cone shell, which shares the same central axis with the multiplication layer and contacts its upper surface, covering the outer surface of the multiplication layer. The contact surface is a fan-shaped surface with the same inclination angle as the truncated cone of the multiplication layer.

[0055] The PAD layer 108 can be made of a metal material with good conductive properties, and is grown on the upper surface of the passivation layer 107 , in the shape of a hollow truncated cone shell with an inclination angle of 6 to 10 degrees, and a thickness of 100 to 500 nm.

[0056] The PAD layer is a hollow truncated cone shell, which has the same central axis as the passivation layer 107 and contacts its upper surface, covering the outer surface of the passivation layer 107. The contact surface is a fan-shaped surface with the same inclination angle as the truncated cone of the passivation layer.

[0057] The metal electrode region 109 comprises an anode region and a cathode region. The anode region is a cylindrical ring, contacting the first multiplication region 102 along a first direction and covering the upper surface of the convex truncated cone of the first multiplication region 102, with a circular contact surface. The cathode region is a cylindrical ring, sharing a common axis with the photosensitive window region and contacting it along the first direction, covering the photosensitive window region, with a circular contact surface. The thickness ranges from 300 to 800 nm; the ring width / cylinder diameter ranges from 40 to 80 nm. The metal electrode region 109 is a Ti metal electrode.

[0058] The photosensitive window area is in a circular shape and is located on the upper surface area of ​​the truncated cone of the fifth multiplication area after the top layer of the passivation layer 107 and the PAD layer 108 is etched. The outer ring diameter is between 400 and 750 nm; the inner ring diameter is the cylindrical diameter of the cathode area of ​​the metal electrode area 109.

[0059] The preparation process of a pocket-doped 4H-SiC-based avalanche photodiode device is as follows: Figure 2 As shown, it includes five parts: layer-by-layer growth and layer-by-layer ion doping, device mesa etching, device surface passivation, photosensitive window etching, and ohmic electrode preparation.

[0060] The first multiplication region 102, the second multiplication region 103, the third multiplication region 104, the fourth multiplication region 105, the fifth multiplication region 106, the passivation layer 107, the PAD layer 108 and the metal electrode region 109 are grown in sequence on the substrate layer 101 by chemical vapor deposition; particles of specified type and concentration are implanted layer by layer by ion implantation.

[0061] Mesa etching uses photoresist reflow technology and dry cycle etching process in a variable temperature environment to prepare low-damage mesas with specified tilt angles to ensure that the electric field is evenly distributed in the depletion region when the device is operating, and effectively electrically isolates the device from adjacent devices on the integrated circuit.

[0062] Surface passivation is to pre-treat the table and then use PECVD to deposit a 200-300nm passivation layer 107. The passivation layer 107 can reduce contamination, damage, defects and electric field distribution on the surface of the device structure and prevent the device from breaking down prematurely.

[0063] PECVD deposition and a 200-300 nm PAD layer 108 are used. The PAD layer 108 connects the device pins with the external circuit while further protecting the device surface structure.

[0064] The photosensitive window etching is based on a dry-wet two-step etching process with a sacrificial layer protection method to achieve low-damage photosensitive window etching.

[0065] The metal electrode region 109 is prepared by adopting a low-resistance ohmic contact process and high-temperature annealing in a nitrogen atmosphere.

[0066] In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with the examples, but the content of the present invention is not limited to the following examples.

[0067] Comparative Example 1:

[0068] like Figure 3 (a) shows a schematic diagram of the doping concentration of a 4H-SiC APD device along the first direction. The thicknesses of the substrate layer 101, the first multiplication region 102, the second multiplication region 103, the third multiplication region 104, the fourth multiplication region 105, and the fifth multiplication region 106 are 3.0, 3.0, 0.5, 0.2, 0.5, and 0.3 μm, respectively. The first multiplication region 102 is p-type doped, and the substrate layer, the second multiplication region, the third multiplication region, the fourth multiplication region, and the fifth multiplication region are all n-type doped, with doping concentrations of 1*10 19 、-1*10 19 , 1*10 15 , 5*10 18 , 1*10 15 and 1*10 19 cm -3 (The negative sign indicates p-type doping only).

[0069] Example 2:

[0070] like Figure 3(b) shows a schematic diagram of the doping concentration of a pocket-doped 4H-SiC-based avalanche photodiode device along the first direction. The thicknesses of the substrate layer 101, the first multiplication region 102, the second multiplication region 103, the third multiplication region 104, the fourth multiplication region 105 and the fifth multiplication region 106 are 3.0, 3.0, 0.5, 0.2, 0.5 and 0.3 μm, respectively. The first multiplication region 102 is p-type doped, and the substrate layer, the second multiplication region, the third multiplication region, the fourth multiplication region and the fifth multiplication region are all n-type doped; the substrate layer 101 is uniformly doped with a doping concentration of 1*10 19 cm -3 The first multiplication region 102 is Gaussian doped, with a doping concentration from bottom to top of -1*10 19 ~-1*10 15 cm -3 Uniform decreasing distribution (negative sign indicates only p-type doping); the second multiplication region 103, the third multiplication region 104, the fourth multiplication region 105 and the fifth multiplication region 106 are Gaussian doped, and the doping concentration is 5*10 from the third multiplication region 104 to the second multiplication region 103. 18 ~1*10 15 cm -3 Evenly distributed in decreasing order, and the fourth doubling zone 105 is 5*10 18 ~1*10 15 cm -3 The fifth multiplication zone 106 is uniformly doped with a doping concentration of 1*10 19 cm -3 .

[0071] The epitaxial structure of Example 2 is exactly the same as that of Comparative Example 1, except for the doping type and doping concentration of each layer.

[0072] Figure 3 (a) and Figure 3 Compared with the device structure in (b), the advantage of Example 2 over the traditional SiCAPD device in Control Example 1 is that the introduction of the Pocket high doping concentration region makes the electric field distribution in the multiplication region more uniform, and the possibility of premature breakdown of the device surface is smaller; in addition, the Pocket high doping is more consistent with the physical doping concentration distribution formed by the ion implantation process.

[0073] The advantages of this pocket-doped 4H-SiC-based avalanche photodiode device will be further illustrated below by simulating the device electrical performance data using the Sentaurus TCAD simulation tool.

[0074] like Figure 4As shown in the figure, the spherical scatter plot represents the volt-ampere characteristic curve of the comparative example 1, and the straight line, line segment, and dotted line respectively represent the maximum doping concentration value of 5*10 in the Gaussian doping distribution of the second multiplication region 103, the third multiplication region 104, and the fourth multiplication region 105 in the embodiment 2. 18 , 1*10 18 , 1*10 17 cm -3 (The minimum doping concentration is 1*10 15 cm -3 , the same below) is the volt-ampere characteristic curve, where Figure 4 (a) is the forward voltage, Figure 4 (b) is the reverse voltage. It is obvious that the leakage current of Example 2 is smaller at 0V voltage, and the maximum doping concentration of Gaussian doping is 1*10 17 cm -3 The device has the smallest leakage current magnitude and the largest breakdown voltage. Considering the maximum doping concentration of 5*10 18 cm -3 Compared with the control example 1, the embodiment 2 has a smaller breakdown voltage, which is manifested as smaller energy loss and power consumption, and is more advantageous in actual engineering applications.

[0075] like Figure 5 As shown, the spherical scatter plot represents the current gain curve of the comparative example 1, and the straight line represents the maximum doping concentration value of 5*10 in the Gaussian doping distribution of the second multiplication region 103, the third multiplication region 104, and the fourth multiplication region 105 in the embodiment 2. 18 , 1*10 18 , 1*10 17 cm -3 Current gain curve under 280nm monochromatic light. Compared with the control example 1, the doping concentration in Example 2 has a larger current gain at the same voltage before the breakdown voltage; and Example 2 shows a current gain significantly greater than 1*10 5 The current gain is significantly improved.

[0076] like Figure 6 As shown in FIG. 1 , the maximum doping concentration value in the Gaussian doping distribution of the second multiplication region 103, the third multiplication region 104, and the fourth multiplication region 105 in the pocket-doped 4H-SiC-based avalanche photodiode device of Example 2 is 5*10 18 cm -3 The response spectrum in the ultraviolet and visible light range of 200-450nm. The quantum efficiency peak of Example 1 under 275nm monochromatic light is 62%, and the ultraviolet-visible light suppression ratio is as high as 2816.5, with an extremely high signal-to-noise ratio, reaching the current industry-leading level.

[0077] The 4H-SiC APD device structure, incorporating a highly doped pocket region, demonstrates exceptional performance: extremely low leakage current, fast photoresponse, high current signal gain, excellent signal-to-noise ratio, and low mesa breakdown probability. These properties offer broad potential for UV detection in extreme environments and provide guidance for the fabrication of high-performance 4H-SiC APD devices.

[0078] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A pocket-doped 4H-SiC-based avalanche photodiode device, characterized in that: include: Substrate layer, multiplication layer, passivation layer, PAD layer, metal electrode region and photosensitive window region; The substrate layer is cylindrical and is located at the bottom layer of the pocket-doped 4H-SiC-based avalanche photodiode device; The multiplication layer is in the form of a convex truncated cone, shares a common central axis with the substrate layer, and contacts the substrate layer along a first direction, wherein the first direction is the central axis of the substrate layer upwards; The multiplication layer is divided into five multiplication zones along the first direction, namely the first multiplication zone, the second multiplication zone, the third multiplication zone, the fourth multiplication zone and the fifth multiplication zone. The five multiplication zones share a central axis along the first direction and are in contact with each other in sequence. The first multiplication zone is in the form of a convex frustum, and the second, third, fourth and fifth multiplication zones are in the form of frustum. The frustum of the first multiplication zone, the second, third, fourth and fifth multiplication zones have the same inclination angle. The doping concentration of the third multiplication region is higher than that of the second multiplication region and the fourth multiplication region, and the second multiplication region, the third multiplication region and the fourth multiplication region adopt pocket doping; The contact surfaces between the substrate layer and the first, second, third, fourth and fifth multiplication regions are all circular surfaces whose outer normals are along the first direction; The passivation layer is a hollow truncated cone shell, having a common central axis with the multiplication layer and in contact with its upper surface, covering the outer surface of the multiplication layer, and the contact surface is a fan-shaped surface with the same inclination angle as the truncated cone of the multiplication layer; The PAD layer is a hollow truncated cone shell, having a common central axis with the passivation layer and in contact with its upper surface, covering the outer surface of the passivation layer, and the contact surface is a fan-shaped surface with the same inclination angle as the truncated cone of the passivation layer; The photosensitive window area is annular and is located on the upper surface of the fifth multiplication zone; The metal electrode area includes an anode area and a cathode area, wherein the anode area is a cylindrical ring body, contacts the first multiplication area along the first direction, covers the upper surface of the convex cone of the first multiplication area, and the contact surface is a circular ring; the cathode area is a cylinder, shares the same central axis with the photosensitive window area and contacts along the first direction, covers the photosensitive window area, and the contact surface is a circle.

2. The pocket-doped 4H-SiC-based avalanche photodiode device according to claim 1, characterized in that: The substrate layer and the multiplication layer are made of the same material.

3. The pocket-doped 4H-SiC-based avalanche photodiode device according to claim 2, characterized in that: The band gap of the multiplication layer is greater than the band gap of the substrate layer.

4. The pocket-doped 4H-SiC-based avalanche photodiode device according to claim 1, characterized in that: The first multiplication region has a different doping type from the other multiplication regions; the substrate layer, the second multiplication region, the third multiplication region, the fourth multiplication region and the fifth multiplication region have the same doping type.

Images