Avalanche photodetector

Abstract

The application relates to an avalanche photodetector. The avalanche photodetector comprises at least one avalanche photodetector unit; the avalanche photodetector unit comprises an N-type doped region, a P-type doped region, a first intrinsic region, a second intrinsic region and a third intrinsic region; the N-type doped region, the intrinsic region and the P-type doped region are sequentially arranged along a first direction; the first intrinsic region, the second intrinsic region and the third intrinsic region are sequentially arranged along a second direction; the length of the second intrinsic region in the first direction is less than the length of the first intrinsic region and the third intrinsic region in the first direction, so that the N-type doped region and the P-type doped region form a finger structure, unipolar ionization can be realized, all the energy obtained from the electric field is used for collision ionization as much as possible, and the holes can be maintained in a low electric field region to drift, so that the avalanche photodetector realizes low-voltage working and keeps the advantages of high sensitivity.

Description

Technical Field

[0001] This application relates to the field of photodetector technology, and in particular to an avalanche photodetector. Background Technology

[0002] Avalanche photodiodes (APDs), also known as avalanche photodetectors, offer advantages such as high speed and high sensitivity. They can be combined with complementary metal-oxide-semiconductor (CMOS) devices for applications in photoelectric detection, optical communication, quantum computing, and many other fields. However, APD devices typically operate at voltages greater than 10V, significantly higher than CMOS devices, thus necessitating a reduction in their operating voltage.

[0003] In traditional technologies, the operating voltage of APD devices is usually reduced by shortening the avalanche zone or increasing the electric field in the avalanche zone. However, these methods can lead to bipolar ionization, which reduces the sensitivity of the APD device. Summary of the Invention

[0004] Therefore, it is necessary to provide an avalanche photodetector that can balance low voltage and high sensitivity to address the aforementioned technical problems.

[0005] This application provides an avalanche photodetector. The avalanche photodetector includes: at least one avalanche photodetector unit; the avalanche photodetector unit includes an N-type doped region, a P-type doped region, and an intrinsic region, the intrinsic region including a first intrinsic region, a second intrinsic region, and a third intrinsic region;

[0006] The N-type doped region, the intrinsic region, and the P-type doped region are arranged sequentially along the first direction;

[0007] The first, second, and third intrinsic zones are arranged sequentially along the second direction; the first direction is perpendicular to the second direction.

[0008] The length of the second intrinsic region in the first direction is less than the length of the first intrinsic region in the first direction, and is also less than the length of the third intrinsic region in the first direction, so that the N-type doped region and the P-type doped region form an interdigital structure.

[0009] In one embodiment, the first intrinsic region includes a first sub-intrinsic region and a second sub-intrinsic region, the third intrinsic region includes a third sub-intrinsic region and a fourth sub-intrinsic region, the N-type doped region includes a first sub-doped region and a second sub-doped region, and the P-type doped region includes a third sub-doped region and a fourth sub-doped region.

[0010] The first sub-intrinsic region is a region of a predetermined length in the middle of the first intrinsic region in the first direction; the second sub-intrinsic region is the region in the first intrinsic region excluding the first sub-intrinsic region; the length of the first sub-intrinsic region in the third direction is greater than the length of the second intrinsic region in the third direction; the third direction is perpendicular to the first direction and the second direction;

[0011] The third sub-intrinsic region is a region of a predetermined length in the middle of the third intrinsic region in the first direction, and the fourth sub-intrinsic region is the region in the third intrinsic region excluding the third sub-intrinsic region. The length of the third sub-intrinsic region in the third direction is greater than the length of the fourth intrinsic region in the third direction.

[0012] The first sub-doped region, the second intrinsic region, and the third sub-doped region are arranged sequentially along the first direction;

[0013] The second sub-doped region is the region in the N-type doped region other than the first sub-doped region, and the length of the first sub-doped region in the third direction is greater than the length of the second sub-doped region in the third direction;

[0014] The fourth sub-doped region is the region in the P-type doped region other than the third sub-doped region, and the length of the third sub-doped region in the third direction is greater than the length of the fourth sub-doped region in the third direction.

[0015] In one embodiment, the sum of the lengths of the first sub-doped region, the second intrinsic region, and the third sub-doped region in the first direction is equal to the preset length;

[0016] The first sub-intrinsic region, the third sub-intrinsic region, the first sub-doped region, the second intrinsic region, and the third sub-doped region are silicon waveguide structures.

[0017] In one embodiment, the avalanche photodetector unit includes a germanium absorption region;

[0018] The germanium absorption region is disposed on the second intrinsic region along a third direction.

[0019] In one embodiment, the cross-sectional shape of the germanium absorption region on the first plane is the same as the cross-sectional shape of the second intrinsic region on the first plane; the first plane is the plane containing the first direction and the second direction.

[0020] In one embodiment, the avalanche photodetector includes a plurality of avalanche photodetector units, which are arranged along a second direction.

[0021] In one embodiment, the first intrinsic region of the first avalanche photoelectric detection unit coincides with the third intrinsic region of the second avalanche photoelectric detection unit, and the first intrinsic region of the second avalanche photoelectric detection unit coincides with the third intrinsic region of the third avalanche photoelectric detection unit; the first avalanche photoelectric detection unit, the second avalanche photoelectric detection unit, and the third avalanche photoelectric detection unit are any three adjacent avalanche photoelectric detection units among the plurality of avalanche photoelectric detection units.

[0022] In one embodiment, the germanium absorption regions of multiple avalanche photodetector units constitute a distributed Bragg reflector.

[0023] In one embodiment, the length of the second intrinsic region along the first direction is 100 nm.

[0024] In one embodiment, the lengths of the first intrinsic region and the third intrinsic region along the first direction are not less than 100 nm and not greater than 1 mm.

[0025] The aforementioned avalanche photodetector includes: at least one avalanche photodetector unit; the avalanche photodetector unit includes an N-type doped region, a P-type doped region, and an intrinsic region, the intrinsic region including a first intrinsic region, a second intrinsic region, and a third intrinsic region; the N-type doped region, the intrinsic region, and the P-type doped region are arranged sequentially along a first direction; the first intrinsic region, the second intrinsic region, and the third intrinsic region are arranged sequentially along a second direction; the first direction is perpendicular to the second direction; the length of the second intrinsic region in the first direction is less than the length of the first intrinsic region in the first direction, and is also less than the length of the third intrinsic region in the first direction, so that the N-type doped region and the P-type doped region form an interdigital structure. The interdigital structure in this embodiment enables unipolar ionization, resulting in almost no electron scattering. The energy obtained from the electric field is used as much as possible for collisional ionization, while allowing as many holes as possible to drift in the low electric field region, thus enabling the avalanche photodetector to achieve the advantage of low-voltage operation while maintaining high sensitivity. Attached Figure Description

[0026] Figure 1 This is one of the structural schematic diagrams of the avalanche photodetector provided in the embodiments of this application;

[0027] Figure 2 This is a schematic diagram of a charge carrier transport process provided in an embodiment of this application;

[0028] Figure 3 This is a second schematic diagram of the avalanche photodetector provided in the embodiments of this application;

[0029] Figure 4 This is the third schematic diagram of the avalanche photodetector provided in the embodiments of this application;

[0030] Figure 5This is the fourth schematic diagram of the avalanche photodetector provided in the embodiments of this application;

[0031] Figure 6 This is the fifth schematic diagram of the avalanche photodetector provided in the embodiments of this application.

[0032] Explanation of reference numerals in the attached figures:

[0033] 101: N-type doped region; 102: P-type doped region; 103: First intrinsic region;

[0034] 104: Second Sub-Region; 105: Third Sub-Region; 301: First Sub-Region;

[0035] 302: Second sub-intrinsic region; 303: Third sub-intrinsic region; 304: Fourth sub-intrinsic region;

[0036] 305: First sub-doped region; 306: Second sub-doped region; 307: Third sub-doped region;

[0037] 308: Fourth sub-doped region; 401: Germanium absorption region. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0039] Avalanche photodiodes (APDs), also known as avalanche photodetectors, offer advantages such as high speed and high sensitivity. They can be combined with complementary metal-oxide-semiconductor (CMOS) devices for applications in photoelectric detection, optical communication, quantum computing, and many other fields. However, APD devices typically operate at voltages greater than 10V, significantly higher than CMOS devices, thus necessitating a reduction in their operating voltage.

[0040] In traditional technologies, the operating voltage of APD devices is typically reduced by shortening the avalanche region or increasing the electric field within it, such as through interdigitated or multi-electrode structures. However, as the electric field strength in the avalanche region increases, bipolar ionization is more likely to occur, introducing significant excess noise and degrading device sensitivity. In other words, these methods present a trade-off between low voltage and high sensitivity.

[0041] In one embodiment, such as Figure 1 As shown, Figure 1This is one of the structural schematic diagrams of the avalanche photodetector provided in the embodiments of this application. The avalanche photodetector includes: at least one avalanche photodetector unit; the avalanche photodetector unit includes an N-type doped region 101, a P-type doped region 102 and an intrinsic region, the intrinsic region including a first intrinsic region 103, a second intrinsic region 104 and a third intrinsic region 105.

[0042] In the embodiments of this application, Figure 1 The structure shown is the structure of an avalanche photodetector unit, that is, the structure of an avalanche photodetector containing only one avalanche photodetector unit.

[0043] The N-type doped region 101, the intrinsic region, and the P-type doped region 102 are arranged sequentially along the first direction, that is, the intrinsic region is arranged between the N-type doped region 101 and the P-type doped region 102 along the first direction.

[0044] Optionally, the intrinsic region includes a first intrinsic region 103, a second intrinsic region 104, and a third intrinsic region 105, wherein the first intrinsic region 103, the second intrinsic region 104, and the third intrinsic region 105 are made of the same material.

[0045] For example, in addition to Si or Si / Ge, the materials of the avalanche photodetectors in the embodiments of this application may also include III-V group materials, etc.

[0046] The first primary defense zone 103, the second primary defense zone 104, and the third primary defense zone 105 are arranged sequentially along the second direction. The first direction is perpendicular to the second direction.

[0047] For example, the intrinsic region is the undoped region.

[0048] In this embodiment, the first direction and the second direction are two mutually perpendicular directions on the same plane. The third direction is a direction perpendicular to both the first and second directions; that is, the third direction is perpendicular to the plane defined by the first and second directions. Taking a spatial rectangular coordinate system as an example, the first direction can be considered as the x-axis direction, the second direction as the y-axis direction, and the third direction as the z-axis direction.

[0049] It should be noted that the above example using a spatial rectangular coordinate system is only to provide a clearer explanation of the relationship between the first direction, the second direction, and the third direction in the embodiments of this application, and does not limit the first direction to be a horizontal direction. The first direction, the second direction, and the third direction can be any three directions that satisfy the above-mentioned vertical relationship.

[0050] The length of the second intrinsic region 104 in the first direction is less than the length of the first intrinsic region 103 in the first direction, and is also less than the length of the third intrinsic region 105 in the first direction, so that the N-type doped region 101 and the P-type doped region 102 form an interdigitated structure.

[0051] For example, such as Figure 1 As shown, since the length of the second intrinsic region 104 in the first direction is less than the length of the first intrinsic region 103 in the first direction, and is less than the length of the third intrinsic region 105 in the first direction, the N-type doped region 101 and the P-type doped region 102 can form an interdigitated structure.

[0052] Optionally, the lengths of the first intrinsic region, the second intrinsic region, and the third intrinsic region range from 100 nm to 1 mm.

[0053] It should be noted that, Figure 1 The avalanche photodetector structure shown is only one possible implementation. When the length of the second intrinsic region in the first direction is less than the length of the first intrinsic region in the first direction, and also less than the length of the third intrinsic region in the first direction, the N-type doped region, P-type doped region, and intrinsic region are not limited to the shape shown in the figure. In other words, the key to the finger-like structure involved in the embodiments of this application lies in the length difference between the intrinsic regions. Besides being square, the N-type doped region, P-type doped region, and intrinsic region can also be inverted trapezoidal, triangular, arc-shaped, etc., and are not specifically limited here.

[0054] In this embodiment, a reverse bias voltage is required when the avalanche photodetector is used. The N-type doped region 101 and the P-type doped region 102 serve as the anode contact region and the cathode contact region, respectively. Since the voltage drop is fixed, the electric field strength and length of the intrinsic region are inversely proportional. The length of the second intrinsic region 104 in the first direction is less than the length of the first intrinsic region 103 in the first direction, and also less than the length of the third intrinsic region 105 in the first direction. Therefore, the second intrinsic region 104 is a high electric field region (i.e., a carrier multiplication region), and the first intrinsic region 103 and the third intrinsic region 105 are low electric field regions (i.e., carrier transport regions).

[0055] Electrons in the carrier multiplication region are in a ballistic transport state and are subject to low scattering, which can efficiently trigger ionization collisions, thus generating avalanche gain. Therefore, the carrier multiplication region can also be called the avalanche multiplication region. Holes are strongly scattered in the carrier multiplication region and are easily scattered into the transport region, where they are transported to the electrodes and collected under the influence of a low electric field. The low electric field helps to prevent ionization collisions that could introduce excessive noise.

[0056] Reference Figure 2 , Figure 2This is a schematic diagram of a carrier transport process provided in an embodiment of this application. During the operation of the avalanche photodetector, light signals can be absorbed through a waveguide structure (such as a silicon waveguide), thereby generating photogenerated carriers. The second intrinsic region 104 has a shorter length in the first direction, which can obtain a stronger electric field at a lower operating voltage, thus ensuring the avalanche gain of electrons. Since the hole scattering rate is higher than that of electrons in silicon, in the high electric field region, electrons achieve ballistic transport and collisional ionization, while holes are scattered into the low electric field region for low-speed drift motion.

[0057] In this embodiment, the avalanche photodetector includes: at least one avalanche photodetector unit; the avalanche photodetector unit includes an N-type doped region, a P-type doped region, and an intrinsic region, the intrinsic region including a first intrinsic region, a second intrinsic region, and a third intrinsic region; the N-type doped region, the intrinsic region, and the P-type doped region are arranged sequentially along a first direction; the first intrinsic region, the second intrinsic region, and the third intrinsic region are arranged sequentially along a second direction; the first direction is perpendicular to the second direction; the length of the second intrinsic region in the first direction is less than the length of the first intrinsic region in the first direction, and is also less than the length of the third intrinsic region in the first direction, so that the N-type doped region and the P-type doped region form an interdigital structure. The interdigital structure in this embodiment can achieve unipolar ionization, so that electrons are almost not scattered, and the energy obtained from the electric field is used as much as possible for collisional ionization, while allowing as many holes as possible to drift in the low electric field region, thereby enabling the avalanche photodetector to achieve the advantage of low voltage operation while maintaining high sensitivity.

[0058] In one embodiment, the collisional ionization threshold energy of electrons in silicon is approximately 1.6 eV. If all the energy an electron gains from the electric field is used for collisional ionization, then at a maximum of 3 collisional ionizations can occur under a 5 V reverse bias. This means that in the avalanche photodetector provided in this embodiment, electrons will have… The theoretical limit of gain is achieved. Meanwhile, due to the realization of monopolar ionization, the excess noise of the avalanche photodetector is also very low, thus giving the avalanche photodetector higher sensitivity.

[0059] Reference Figure 3 , Figure 3 This is a second schematic diagram of the avalanche photodetector provided in the embodiments of this application. Based on the above embodiments, Figure 1 This can be viewed as a top view of an avalanche photodetector. Given that the top view structure of the avalanche photodetector is already determined, its three-dimensional structure can be further defined. For example... Figure 3 As shown, Figure 3 The diagram shows a three-dimensional structure of an avalanche photodetector provided in an embodiment of this application.

[0060] The first intrinsic region 103 includes a first sub-intrinsic region 301 and a second sub-intrinsic region 302; the third intrinsic region 105 includes a third sub-intrinsic region 303 and a fourth sub-intrinsic region 304; the N-type doped region 101 includes a first sub-doped region 305 and a second sub-doped region 306; and the P-type doped region 102 includes a third sub-doped region 307 and a fourth sub-doped region 308.

[0061] It should be noted that the first intrinsic region 103, the third intrinsic region 105, the N-type doped region 101, and the P-type doped region 102 involved in the embodiments of this application are all integrated structures. In other words, the first intrinsic region 103, the third intrinsic region 105, the N-type doped region 101, and the P-type doped region 102 are actually a complete whole. The separation of the first intrinsic region 103, the third intrinsic region 105, the N-type doped region 101, and the P-type doped region 102 here is only to more clearly illustrate the size and position of each component and the relationship between each component. It does not mean that the first intrinsic region 103, the third intrinsic region 105, the N-type doped region 101, and the P-type doped region 102 are actually divided.

[0062] First Sub-Region 301 (i.e. Figure 3 The orange shaded area in the image represents a region of a predetermined length in the middle of the first intrinsic region 103 in the first direction. The second sub-intrinsic region 302 is the region in the first intrinsic region 103 excluding the first sub-intrinsic region 301. The length of the first sub-intrinsic region 301 in the third direction is greater than the length of the second sub-intrinsic region 302 in the third direction. The third direction is perpendicular to the first direction and the second direction.

[0063] Optionally, the first intrinsic region 103 in the third direction is not a structure with uniform thickness, but includes two regions with different thicknesses, namely the first sub-intrinsic region 301 and the second sub-intrinsic region 302. The length of the first sub-intrinsic region 301 in the third direction is the thickness of the first sub-intrinsic region 301, and the length of the second sub-intrinsic region 302 in the third direction is the thickness of the second sub-intrinsic region 302.

[0064] For example, the plane containing the third direction and the first direction can be taken as the second plane, and the cross-sectional shape of the first intrinsic region 103 on the second plane is a "convex" shape.

[0065] Third son, local area 303 (i.e.) Figure 3 The green shaded area in the first direction is a region of a preset length in the middle of the third intrinsic region 105. The fourth sub-intrinsic region 304 is the region in the third intrinsic region 105 other than the third sub-intrinsic region 303. The length of the third sub-intrinsic region 303 in the third direction is greater than the length of the fourth sub-intrinsic region 304 in the third direction.

[0066] Similarly, the third intrinsic region 105 is not a structure with uniform thickness, but includes a third sub-intrinsic region 303 and a fourth sub-intrinsic region 304 with different thicknesses. In other words, the cross-sectional shape of the third intrinsic region 105 on the second plane is also "convex".

[0067] The first sub-doped region 305, the second intrinsic region 104, and the third sub-doped region 307 are sequentially arranged along the first direction. The second sub-doped region 306 is the region in the N-type doped region 101 excluding the first sub-doped region 305, and the length of the first sub-doped region 305 in the third direction is greater than the length of the second sub-doped region 306 in the third direction. The fourth sub-doped region 308 is the region in the P-type doped region 102 excluding the third sub-doped region 307, and the length of the third sub-doped region 307 in the third direction is greater than the length of the fourth sub-doped region 308 in the third direction.

[0068] For example, such as Figure 3 As shown, the N-type doped region 101 and the P-type doped region 102 each include two regions of different thicknesses. The first sub-doped region 305 is the thicker region in the N-type doped region 101, and the third sub-doped region 307 is the thicker region in the P-type doped region 102. Furthermore, the first sub-doped region 305 and the third sub-doped region 307 are respectively disposed on both sides of the second intrinsic region 104 along the first direction.

[0069] Optionally, the first sub-intrinsic region 301, the third sub-intrinsic region 303, the first sub-doped region 305, the second intrinsic region 104, and the third sub-doped region 307 have the same thickness. That is, the lengths of the first sub-intrinsic region 301, the third sub-intrinsic region 303, the first sub-doped region 305, the second intrinsic region 104, and the third sub-doped region 307 in the third direction are all the same.

[0070] Based on the above embodiments, the sum of the lengths of the first sub-doped region, the second intrinsic region, and the third sub-doped region in the first direction is equal to a preset length. The first sub-intrinsic region, the third sub-intrinsic region, the first sub-doped region, the second intrinsic region, and the third sub-doped region are silicon waveguide structures. This silicon waveguide structure is used to absorb optical signals, thereby generating photogenerated carriers. Furthermore, the use of silicon waveguide structures is compatible with CMOS processes and offers advantages such as high integration density, low-loss transmission, excellent photoelectric conversion performance, low power consumption, flexibility, and cost.

[0071] Reference Figure 4 , Figure 4 This is the third schematic diagram of the avalanche photodetector provided in the embodiments of this application. Based on the above embodiments, the avalanche photodetector unit includes a germanium absorption region 401; the germanium absorption region 401 is disposed on the second intrinsic region 104 along a third direction.

[0072] In one embodiment, since germanium can absorb wavelengths such as 1310 nm and 1550 nm that silicon cannot absorb, a germanium absorption region 401 can also be epitaxially grown on the second intrinsic region 104.

[0073] For example, when light propagates in a silicon waveguide structure, a portion of the light field can be coupled into the germanium absorption region 401 in the form of an evanescent wave. The germanium absorption region 401 absorbs this portion of the light field to generate photogenerated carriers, which then diffuse into the high electric field region to carry out an avalanche process similar to that described above.

[0074] It should be noted that the germanium absorption region cannot extend into the low electric field region; otherwise, due to carrier diffusion, the device will behave more like a photodiode (PD) than an avalanche photodiode (APD).

[0075] In this embodiment, the avalanche photodetector unit includes a germanium absorption region. The germanium absorption region is disposed on the second intrinsic region along a third direction, thereby enabling the absorption of wavelengths such as 1310 nm and 1550 nm that silicon cannot absorb, expanding the application scenarios of the avalanche photodetector, and further improving the detection efficiency and sensitivity of the avalanche photodetector.

[0076] Based on the above embodiments, the cross-sectional shape of the germanium absorption region 401 on the first plane is the same as the cross-sectional shape of the second intrinsic region 104 on the first plane. The first plane is the plane containing the first direction and the second direction.

[0077] In one embodiment, a germanium absorption region 401 can be epitaxially grown on the second intrinsic region 104, such that the cross-sectional shape of the germanium absorption region 401 on the first plane is the same as the cross-sectional shape of the second intrinsic region 104 on the first plane. In other words, from a top-view perspective, the germanium absorption region 401 and the second intrinsic region 104 coincide. This prevents the germanium absorption region from extending into the low electric field region and allows the germanium absorption region to absorb the light field coupled in the form of evanescent waves as much as possible.

[0078] Reference Figure 5-6 , Figure 5 This is the fourth schematic diagram of the avalanche photodetector provided in the embodiments of this application. Figure 6 This is the fifth schematic diagram of the avalanche photodetector provided in the embodiments of this application. Based on the above embodiments, the avalanche photodetector includes multiple avalanche photodetector units, which are arranged along a second direction.

[0079] For example, in the structure of the avalanche photodetector described above, the avalanche multiplication region is narrow (e.g., 100 nm) in order to obtain a high electric field at low voltage. However, the width of existing silicon waveguides is generally around 400 nm, necessitating waveguide doping. According to currently available information, waveguide doping does not introduce significant scattering loss. Simultaneously, for silicon or germanium-silicon avalanche photodetectors with the aforementioned structure, the width of the absorption region is also limited to within 100 nm. Considering that its length is also limited by the width of the avalanche region, the optical confinement factor of the absorption region ultimately becomes a constraint on device performance, primarily affecting the unity-gain responsivity and consequently the device's sensitivity.

[0080] In one embodiment, in order to further improve the sensitivity of the avalanche photodetector, the avalanche photodetector unit can be periodically extended in one dimension, that is, multiple avalanche photodetector units are arranged along the second direction, thereby increasing the total length of the second intrinsic region, improving the external quantum efficiency, and ultimately ensuring a certain unity gain responsivity.

[0081] Based on the above embodiments, the first intrinsic region of the first avalanche photoelectric detection unit coincides with the third intrinsic region of the second avalanche photoelectric detection unit, and the first intrinsic region of the second avalanche photoelectric detection unit coincides with the third intrinsic region of the third avalanche photoelectric detection unit; the first avalanche photoelectric detection unit, the second avalanche photoelectric detection unit, and the third avalanche photoelectric detection unit are any three adjacent avalanche photoelectric detection units among a plurality of avalanche photoelectric detection units.

[0082] For example, the first avalanche photoelectric detection unit, the second avalanche photoelectric detection unit, and the third avalanche photoelectric detection unit are three avalanche photoelectric detection units arranged sequentially along the second direction, that is, the second avalanche photoelectric detection unit is disposed between the first avalanche photoelectric detection unit and the third avalanche photoelectric detection unit.

[0083] Optionally, the first intrinsic region of the first avalanche photoelectric detection unit coincides with the third intrinsic region of the second avalanche photoelectric detection unit, and the first intrinsic region of the second avalanche photoelectric detection unit coincides with the third intrinsic region of the third avalanche photoelectric detection unit. That is, the first avalanche photoelectric detection unit and the second avalanche photoelectric detection unit share the first intrinsic region of the first avalanche photoelectric detection unit, and the second avalanche photoelectric detection unit and the third avalanche photoelectric detection unit share the third intrinsic region of the third avalanche photoelectric detection unit.

[0084] like Figure 5-6As shown, when the first intrinsic region of the first avalanche photodetector unit coincides with the third intrinsic region of the second avalanche photodetector unit, a portion of the N-type doped region of the first avalanche photodetector unit will coincide with a portion of the N-type doped region of the second avalanche photodetector unit, and a portion of the P-type doped region of the first avalanche photodetector unit will also coincide with a portion of the P-type doped region of the second avalanche photodetector unit.

[0085] Based on the above embodiments, the germanium absorption regions of multiple avalanche photodetector units constitute a distributed Bragg reflector.

[0086] In one embodiment, by adjusting the duty cycle of the germanium absorption units, a distributed Bragg reflector (DBR) can be formed using periodically arranged germanium absorption regions, thereby further enhancing the confinement of the optical field and improving the unity-gain responsivity.

[0087] In the prior art, a DBR is usually required to be set on the outside of the silicon waveguide transmitting end, which increases the device size. Therefore, the avalanche photodetector provided in this application embodiment also has the advantage of small size.

[0088] Based on the above embodiments, the length of the second intrinsic region along the first direction is 100 nm.

[0089] Based on the above embodiments, the lengths of the first intrinsic region and the third intrinsic region along the first direction are not less than 100 nm and not greater than 1 mm.

[0090] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0091] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application, such as the separation absorption multiplication structure. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. An avalanche photodetector, characterized in that, The avalanche photodetector includes: at least one avalanche photodetector unit; the avalanche photodetector unit includes an N-type doped region, a P-type doped region, and an intrinsic region, the intrinsic region including a first intrinsic region, a second intrinsic region, and a third intrinsic region; The N-type doped region, the intrinsic region, and the P-type doped region are arranged sequentially along the first direction; The first intrinsic region, the second intrinsic region, and the third intrinsic region are arranged sequentially along a second direction; the first direction is perpendicular to the second direction. The length of the second intrinsic region in the first direction is less than the length of the first intrinsic region in the first direction, and is also less than the length of the third intrinsic region in the first direction, so that the N-type doped region and the P-type doped region form an interdigital structure; Wherein, the first intrinsic region includes a first sub-intrinsic region and a second sub-intrinsic region, the third intrinsic region includes a third sub-intrinsic region and a fourth sub-intrinsic region, the N-type doped region includes a first sub-doped region and a second sub-doped region, and the P-type doped region includes a third sub-doped region and a fourth sub-doped region; The first sub-intrinsic region is a region of a predetermined length located in the middle of the first intrinsic region in the first direction; the second sub-intrinsic region is the region in the first intrinsic region excluding the first sub-intrinsic region; the length of the first sub-intrinsic region in the third direction is greater than the length of the second sub-intrinsic region in the third direction; the third direction is perpendicular to the first direction and the second direction. The third sub-intrinsic region is a region of a predetermined length in the middle of the third intrinsic region in the first direction, and the fourth sub-intrinsic region is the region in the third intrinsic region excluding the third sub-intrinsic region. The length of the third sub-intrinsic region in the third direction is greater than the length of the fourth sub-intrinsic region in the third direction. The first sub-doped region, the second intrinsic region, and the third sub-doped region are arranged sequentially along the first direction; The second sub-doped region is the region in the N-type doped region other than the first sub-doped region, and the length of the first sub-doped region in the third direction is greater than the length of the second sub-doped region in the third direction; The fourth sub-doped region is the region in the P-type doped region other than the third sub-doped region, and the length of the third sub-doped region in the third direction is greater than the length of the fourth sub-doped region in the third direction.

2. The avalanche photodetector according to claim 1, characterized in that, The sum of the lengths of the first sub-doped region, the second intrinsic region, and the third sub-doped region in the first direction is equal to the preset length; The first sub-intrinsic region, the third sub-intrinsic region, the first sub-doped region, the second intrinsic region, and the third sub-doped region are silicon waveguide structures.

3. The avalanche photodetector according to claim 2, characterized in that, The avalanche photoelectric detection unit includes a germanium absorption region; The germanium absorption region is disposed on the second intrinsic region along a third direction.

4. The avalanche photodetector according to claim 3, characterized in that, The cross-sectional shape of the germanium absorption region on the first plane is the same as the cross-sectional shape of the second intrinsic region on the first plane; the first plane is the plane containing the first direction and the second direction.

5. The avalanche photodetector according to claim 3, characterized in that, The avalanche photodetector includes multiple avalanche photodetector units, which are arranged along a second direction.

6. The avalanche photodetector according to claim 5, characterized in that, The first intrinsic region of the first avalanche photoelectric detection unit coincides with the third intrinsic region of the second avalanche photoelectric detection unit, and the first intrinsic region of the second avalanche photoelectric detection unit coincides with the third intrinsic region of the third avalanche photoelectric detection unit; the first avalanche photoelectric detection unit, the second avalanche photoelectric detection unit, and the third avalanche photoelectric detection unit are any three adjacent avalanche photoelectric detection units among the plurality of avalanche photoelectric detection units.

7. The avalanche photodetector according to claim 6, characterized in that, The germanium absorption regions of multiple avalanche photodetector units constitute a distributed Bragg reflector.

8. The avalanche photodetector according to any one of claims 1-7, characterized in that, The length of the second intrinsic region along the first direction is 100 nm.

9. The avalanche photodetector according to any one of claims 1-7, characterized in that, The lengths of the first intrinsic region and the third intrinsic region along the first direction are not less than 100 nm and not greater than 1 mm.

Images