Photodetector

Abstract

The application provides a photoelectric detector, which comprises a substrate, a waveguide layer, an absorption layer, a first doped region, a second doped region, an incident light waveguide, a lower contact electrode and an upper contact electrode. The incident light waveguide is connected to one side of the waveguide layer, the lower contact electrode is connected to the first doped region, the upper contact electrode is connected to the second doped region, the upper contact electrode comprises at least three upper contact electrodes which are connected to each other, the extension direction of the at least three upper contact electrodes is consistent with the propagation direction of the light entering the absorption layer from the incident light waveguide, and the at least three upper contact electrodes are distributed around the light field formed in the absorption layer. The absorption layer is adjacent to the incident light waveguide, and a boundary line is formed between the absorption layer and the waveguide layer, and the extension direction of the incident light waveguide is inclined relative to the boundary line. The photoelectric detector has the performance of low return loss and high responsivity.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, and in particular to a photodetector. Background Technology

[0002] A photodetector is an optoelectronic device that converts optical signals into electrical signals and is an essential basic component in optical communication modules. Photodetectors used for high-speed integration include III-V semiconductor photodetectors and germanium-silicon photodetectors. Germanium-silicon photodetectors are compatible with CMOS processes and are widely used in silicon photonics integration. Among germanium-silicon photodetectors, the evanescent wave coupled vertical PIN structure is a mainstream solution.

[0003] However, in evanescent wave coupled vertical PIN photodetectors, the metal electrode is close to the light field in the germanium absorption layer, and since metal absorbs light, this inevitably reduces the photodetector's responsivity. Furthermore, traditional evanescent wave coupled vertical photodetectors also have relatively high return loss. Summary of the Invention

[0004] The purpose of this invention is to provide a photodetector with low return loss and high responsivity.

[0005] To achieve the above-mentioned objective, the present invention provides a photodetector, comprising:

[0006] Substrate;

[0007] A waveguide layer disposed on the substrate;

[0008] An absorption layer is disposed on the waveguide layer;

[0009] A first doped region is formed within the waveguide layer;

[0010] The second doped region is formed within the absorption layer and is located above the absorption layer;

[0011] An incident optical waveguide, wherein the incident optical waveguide is connected to one side of the waveguide layer;

[0012] A lower contact electrode, wherein the lower contact electrode is connected to the first doped region;

[0013] The upper contact electrode is connected to the second doped region. The upper contact electrode includes at least three first contact electrodes that are electrically connected to each other. The extension direction of the at least three first contact electrodes is consistent with the propagation direction of the light entering the absorption layer from the incident light waveguide. The at least three first contact electrodes are distributed around the light field formed in the absorption layer.

[0014] The absorption layer has a boundary line with the waveguide layer at a position adjacent to the incident light waveguide, and the extension direction of the incident light waveguide is inclined relative to the boundary line.

[0015] As a further improvement of the present invention, the at least three first contact electrodes include a first upper contact electrode, a second upper contact electrode and a third upper contact electrode, the first upper contact electrode being disposed close to the incident light waveguide, the third upper contact electrode being disposed away from the incident light waveguide, and the second upper contact electrode being located at the middle of the absorption layer and extending in the propagation direction of the light entering the absorption layer.

[0016] As a further improvement of the present invention, the upper contact electrode further includes a plurality of second contact electrodes, the first contact electrode and the second contact electrode being electrically connected, and the plurality of second contact electrodes being distributed along the propagation direction of light entering the absorption layer.

[0017] As a further improvement of the present invention, the extension direction of the second contact electrode is perpendicular to the extension direction of the first contact electrode, and each first contact electrode is connected to at least one second contact electrode.

[0018] As a further improvement of the present invention, the width of the first contact electrode in the direction perpendicular to the propagation direction of light entering the absorption layer is greater than the width of the second contact electrode in the propagation direction of light entering the absorption layer.

[0019] As a further improvement of the present invention, the photodetector also has an electrode connecting leg and a connecting electrode connected to the electrode connecting leg, wherein the electrode connecting leg is connected to the first contact electrode.

[0020] As a further improvement of the present invention, the second contact electrode is disposed between the first upper contact electrode and the second upper contact electrode, and extends in a direction perpendicular to the propagation direction of light entering the absorption layer.

[0021] As a further improvement of the present invention, the second upper contact electrode and the first upper contact electrode are offset in the direction of light propagation entering the absorption layer.

[0022] As a further improvement of the present invention, in the direction of light propagation entering the absorption layer, the extension length of the second upper contact electrode is greater than the extension length of the first upper contact electrode.

[0023] As a further improvement of the present invention, the absorption layer has a central axis extending in the direction of light propagation entering the absorption layer, and the third upper contact electrode and the first upper contact electrode are located on the same side of the central axis.

[0024] As a further improvement of the present invention, in the direction of light propagation entering the absorption layer, the extension length of the second upper contact electrode is greater than the extension length of the third upper contact electrode.

[0025] As a further improvement of the present invention, in the direction of light propagation entering the absorption layer, the opposite ends of the third upper contact electrode are located within the extension range of the second upper contact electrode.

[0026] As a further improvement of the present invention, the incident light waveguide includes a first incident light waveguide and a second incident light waveguide, the first incident light waveguide and the second incident light waveguide being connected to both sides of the waveguide layer.

[0027] As a further improvement of the present invention, the at least three first contact electrodes include a first upper contact electrode, a second upper contact electrode, and a third upper contact electrode. The first upper contact electrode is disposed close to the first incident light waveguide, the third upper contact electrode is disposed close to the second incident light waveguide, and the second upper contact electrode is located between the first upper contact electrode and the third upper contact electrode in the direction of light propagation entering the absorption layer.

[0028] As a further improvement of the present invention, the upper contact electrode includes four first contact electrodes electrically connected to each other. The first contact electrode includes a first upper contact electrode, a second upper contact electrode, a third upper contact electrode, and a fourth upper contact electrode. The first upper contact electrode and the fourth upper contact electrode are respectively disposed close to the first incident light waveguide and the second incident light waveguide. In the propagation direction of the light entering the absorption layer, the second and third upper contact electrodes are located between the first upper contact electrode and the fourth upper contact electrode. The first upper contact electrode and the fourth upper contact electrode are respectively disposed on both sides of the central axis, and the second upper contact electrode and the third upper contact electrode are respectively disposed on both sides of the central axis.

[0029] As a further improvement of the present invention, the acute angle formed by the intersection of the extension direction of the incident light waveguide and the boundary line is in the range of 70° to 85°.

[0030] The beneficial effects of this invention are as follows: The photodetector of this invention ensures low return loss performance by connecting the incident light waveguide to one side of the waveguide layer and setting the extension direction of the incident light waveguide to be inclined relative to the aforementioned boundary line. Simultaneously, by configuring the upper contact electrode to include at least three electrically connected first contact electrodes, and the extension direction of the at least three first contact electrodes is consistent with the propagation direction of the light entering the absorption layer from the incident light waveguide, the at least three first contact electrodes are distributed around the light field formed within the absorption layer. Thus, while ensuring low return loss, the absorption of the optical signal by the metal electrode can be minimized, while the area of ​​the metal electrode can be maximized, thereby improving the overall performance of the photodetector. Attached Figure Description

[0031] Figure 1 This is a top view of the first embodiment of the photodetector of the present invention.

[0032] Figure 2 yes Figure 1 The diagram shows a cross-sectional view of the photodetector.

[0033] Figure 3 This is a top view of the second embodiment of the photodetector of the present invention.

[0034] Figure 4 This is a top view of the third embodiment of the photodetector of the present invention.

[0035] Figure 5 yes Figure 1 The light field distribution diagram of the metal electrode layer in the photodetector is shown.

[0036] Figure 6 This is a top-view structural diagram of a photodetector, a commonly used technology. Detailed Implementation

[0037] The present invention will now be described in detail with reference to the embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional modifications made by those skilled in the art based on these embodiments are included within the scope of protection of the present invention.

[0038] The terms used herein, such as “above,” “over,” “below,” and “under,” indicating spatial relative position, are for illustrative purposes to describe the relationship of one unit or feature relative to another unit or feature as shown in the accompanying drawings. The terms of spatial relative position may be intended to include different orientations of the device in use or operation other than those shown in the figures. For example, if the device in the figures is flipped, a unit described as being “below” or “under” another unit or feature would be located “above” another unit or feature. Therefore, the exemplary term “below” can encompass both above and below orientations. The device may be oriented in other ways (rotated 90 degrees or otherwise) and the spatially related descriptive terms used herein shall be interpreted accordingly.

[0039] like Figure 6 The diagram shows a top-view schematic of a photodetector in a commonly used technology. The waveguide layer 13' of this photodetector is connected to the incident light waveguide 3'. The incident light waveguide 3' is tilted to the left of the absorption layer 2' to reduce the return loss of the photodetector. The lower contact electrodes 43' are located on both sides of the longitudinal direction of the absorption layer 2'. Because the light is incident from the left at an angle, the light field at the upper left corner of the absorption layer 2' is relatively weak. As the light propagates, it is excessively absorbed by the absorption layer 2', resulting in a weaker light field on the right side, especially at the upper right corner and the lower right-middle corner. The upper contact electrode 41' is elongated and positioned on the absorption layer 2'. Since metal has a very high absorption rate of light, this can lead to a low responsivity of the photodetector.

[0040] like Figure 1 and Figure 2 The image shown is a first embodiment of the photodetector of the present invention. For ease of explanation, the lateral direction will be referred to below as... Figure 1 The X direction shown is the longitudinal direction. Figure 1 The Y direction is shown. The lateral direction is perpendicular to the longitudinal direction. The photodetector of the present invention includes: a substrate 1, a waveguide layer 13, an absorption layer 2, an incident light waveguide 3, a first doped region 5, a second doped region 6, an upper contact electrode, and a lower contact electrode 43.

[0041] The substrate 1 includes at least a silicon layer 11. A waveguide layer 13 is formed on the silicon layer 11. In some embodiments, the substrate 1 further includes a silicon oxide layer 12 disposed on the upper side of the silicon layer 11.

[0042] The absorption layer 2 is disposed on the waveguide layer 13. The absorption layer 2 is rectangular and has a central axis C-C' extending in the lateral direction.

[0043] The waveguide layer 13 is disposed on the substrate 1. The first doped region 5 is formed within the waveguide layer 13. The second doped region 6 is formed within the absorption layer 2 and is located above the absorption layer 2.

[0044] The upper contact electrode is connected to the second doped region 6. The upper contact electrode includes at least three electrically connected first contact electrodes 41. The extension direction of the at least three first contact electrodes 41 is consistent with the propagation direction of light entering the absorption layer 2 from the incident light waveguide 3. The at least three first contact electrodes 41 are distributed around the light field formed within the absorption layer 2.

[0045] In this invention, the propagation direction of light entering the absorption layer 2 from the incident light waveguide 3 is parallel to... Figure 1 The lateral direction shown. The propagation direction of light entering the absorption layer 2 from the incident light waveguide 3 is perpendicular to... Figure 1 The longitudinal direction is shown.

[0046] The lower contact electrode 43 is connected to the first doped region 5. A pair of lower contact electrodes 43 are disposed on both sides of the absorption layer 2 along the longitudinal direction.

[0047] The incident light waveguide 3 is connected to one side of the waveguide layer 13. For example... Figure 1 As shown, the absorption layer 2, adjacent to the incident light waveguide 3, forms a boundary line L-L' with the waveguide layer 13, and the extension direction of the incident light waveguide 3 is inclined relative to the boundary line L-L'. Here, inclination means that the included angle between the two is an acute angle.

[0048] The incident light waveguide 3 has a starting end and an ending end that are arranged opposite to each other, and the ending end is the junction of the incident light waveguide 3 and the waveguide layer 13. The starting end and the ending end are arranged opposite to each other in the extension direction of the incident light waveguide 3. The extension direction of the incident light waveguide 3 is consistent with the propagation direction of the incident light.

[0049] The photodetector also has an electrode connecting leg 7 connected to the first contact electrode 41 and a connecting electrode 8 connected to the electrode connecting leg 7. The first contact electrode 41 is electrically connected to the connecting electrode 8 through the electrode connecting leg 7. The connecting electrode 8 is used for electrical connection with other devices.

[0050] The photodetector of the present invention connects the incident light waveguide 3 to one side of the waveguide layer 13 and sets the extension direction of the incident light waveguide 3 to be inclined relative to the boundary line L-L', thereby ensuring the low return loss performance of the photodetector.

[0051] Furthermore, the photodetector's upper contact electrode is configured to include at least three electrically connected first contact electrodes 41. The extension direction of the at least three first contact electrodes 41 is aligned with the propagation direction of light entering the absorption layer 2 from the incident light waveguide 3. The at least three first contact electrodes 41 are distributed around the light field formed within the absorption layer 2. This configuration minimizes the absorption of the optical signal by the metal electrodes while maximizing the area of ​​the metal electrodes, thereby improving the overall performance of the photodetector.

[0052] like Figure 2 As shown, in some embodiments of the present invention, the waveguide layer 13 is disposed on the silicon oxide layer 12.

[0053] The first doped region 5 is disposed on the waveguide layer 13, the absorption layer 2 is disposed on the first doped region 5, and the second doped region 6 is disposed on the absorption layer 2 to form a vertical PIN photodetector. The first doped region 5 and the second doped region 6 have opposite doping polarities. In this embodiment, the first doped region 5 is heavily N-type doped, and the second doped region 6 is heavily P-type doped.

[0054] In some embodiments of the present invention, the incident light waveguide 3 is located at least on one side of the absorption layer 2 in the lateral direction, and the extension direction (i.e., the light propagation direction) of the incident light waveguide 3 is inclined relative to the central axis C-C'. The at least three first contact electrodes 41 are disposed on the second doped region 6.

[0055] The at least three first contact electrodes 41 are specifically a first upper contact electrode 411, a second upper contact electrode 412, and a third upper contact electrode 413. The first upper contact electrode 411 is disposed close to the incident light waveguide 3, and the third upper contact electrode 413 is disposed away from the incident light waveguide 3. The second upper contact electrode 412 is located in the middle of the absorption layer 2 and extends in the direction of light propagation entering the absorption layer 2, so as to maximize the area of ​​the metal electrode on the opposite side of the first upper contact electrode 411.

[0056] The centers of the first upper contact electrode 411 and the end of the incident light waveguide 3 are positioned on opposite sides of the central axis C-C', so that light entering the absorption layer 2 from the incident light waveguide 3 can fully penetrate the absorption layer 2, thereby improving coupling efficiency. The second upper contact electrode 412 and the first upper contact electrode 411 are positioned on opposite sides of the central axis C-C'.

[0057] In some embodiments of the present invention, the upper contact electrode further includes a plurality of second contact electrodes 42, and the first contact electrode 41 and the second contact electrodes 42 are electrically connected. The plurality of second contact electrodes 42 are distributed along the propagation direction of light entering the absorption layer 2. The second contact electrodes 42 are located at the upper part of the light field formed within the absorption layer 2. The extending direction of the second contact electrodes 42 is perpendicular to the extending direction of the first contact electrode 41. The present invention, through the rational design and arrangement of the upper contact electrodes 41 and 42 disposed on the absorption layer 2, makes the light field coupled to the absorption layer 2 more uniformly distributed.

[0058] The first and second contact electrodes 41 and 42 are disposed on the second doped region 6. The lower contact electrode 43 is disposed on the first doped region 5. The lower contact electrode 43 and the upper contact electrode collect photogenerated carriers generated by the absorption layer 2 absorbing light, thereby forming a photocurrent.

[0059] In some embodiments of the present invention, the first and second contact electrodes 41 and 42 are both metal silicides. The first contact electrode 41 is disposed within the deposition area of ​​the absorption layer 2, and the second contact electrode 42 is also disposed within the deposition area of ​​the absorption layer 2.

[0060] Specifically, each of the first contact electrodes 41 is connected to at least one of the second contact electrodes 42. The width of the first contact electrode 41 in the direction perpendicular to the propagation direction of light entering the absorption layer is greater than the width of the second contact electrode 42 in the propagation direction of light entering the absorption layer, thereby ensuring the electrical connection between the first contact electrode 41 and its upper electrode connection leg 7, while improving the responsivity of the photodetector.

[0061] In some embodiments of the invention, the width of the first contact electrode 41 in the longitudinal direction is in the range of 700 to 1000 nm, so that a sufficient width is provided to ensure better electrical connection with the electrode connecting leg 7 disposed on its upper side.

[0062] A plurality of second contact electrodes 42 are arranged at intervals from each other in the direction of light propagation entering the absorption layer, thereby ensuring electrical connection performance at locations with weaker light intensity in the light field through the interval arrangement of the second contact electrodes 42.

[0063] The second contact electrode 42 is disposed between the first upper contact electrode 411 and the second upper contact electrode 412, and extends in a direction perpendicular to the propagation direction of light entering the absorption layer.

[0064] The second upper contact electrode 412 and the first upper contact electrode 411 are offset in the direction of light propagation entering the absorption layer, thereby reducing the absorption of light by the metal and avoiding a decrease in the responsivity of the photodetector. In some embodiments of the present invention, the second metal electrode 412 and the first metal electrode 411 are spaced apart in the direction of light propagation entering the absorption layer, that is, the first end of the second metal electrode 412 and the first metal electrode 411 are spaced apart in the direction of light propagation entering the absorption layer, thereby further reducing the absorption of light by the metal electrodes.

[0065] In the direction of light propagation entering the absorption layer, the extension length of the second upper contact electrode 412 is greater than the extension length of the first upper contact electrode 411. By setting a sufficiently long metal electrode in a region with a weak light field, the high responsivity of the photodetector is ensured.

[0066] like Figure 1 As shown, the acute angle α formed by the intersection of the extension direction of the incident light waveguide 3 and the boundary line L-L' ranges from 70° to 85°. This reduces light reflection loss and improves quantum efficiency and coupling efficiency.

[0067] The third upper contact electrode 413 and the first upper contact electrode 411 are located on the same side of the central axis. The lateral distance between the third upper contact electrode 413 and the first upper contact electrode 411 is greater than the lateral distance between the second upper contact electrode 412 and the first upper contact electrode 411.

[0068] In the direction of light propagation entering the absorption layer 2, the extension length of the second upper contact electrode 412 is greater than the extension length of the third upper contact electrode 413, thereby maximizing the area of ​​the metal electrode in the location where the light field distribution is weak, so that light can fully penetrate the absorption layer 2.

[0069] In the direction of light propagation entering the absorption layer 2, the opposite ends of the third upper contact electrode 413 are located within the extension range of the second upper contact electrode 412, and the absorption of light by the third upper contact electrode 413 is reduced by controlling the length of the third upper contact electrode 413.

[0070] In one specific embodiment of the present invention, reference is made to... Figure 1 and combined Figure 5 The light field distribution diagram shown has the following characteristics: the thickness of the absorption layer 2 is 0.47 μm; the width of the absorption layer 2 in the direction perpendicular to the propagation direction of the light entering the absorption layer 2 (i.e., the longitudinal direction) is 5 μm; the length of the absorption layer 2 in the propagation direction of the light entering the absorption layer 2 (i.e., the transverse direction) is 18 μm; and the incident angle α of the light is 10°.

[0071] At this time, the specific positions of the three first contact electrodes 41 are as follows:

[0072] The first upper contact electrode 411 is placed on the upper left of the absorption layer 2. It has a width of 0.7 μm and a length of 3 μm. The distance between the first upper contact electrode 411 and the left edge of the absorption layer 2 is 2 μm, and the distance between the first upper contact electrode 411 and the upper edge of the absorption layer 2 is 0.5 μm.

[0073] The second upper contact electrode 412 is placed on the lower right side of the absorption layer 2. It has a width of 0.7 μm and a length of 13 μm. The distance between the second upper contact electrode 412 and the right edge of the absorption layer 2 is 2 μm, and the distance between the second upper contact electrode 412 and the lower edge of the absorption layer 2 is 0.5 μm.

[0074] The third upper contact electrode 413 is placed on the upper right side of the absorption layer 2. It has a width of 0.7 μm and a length of 8 μm. The distance between the third upper contact electrode 413 and the right edge of the absorption layer 2 is 2 μm, and the distance between the third upper contact electrode 413 and the upper edge of the absorption layer 2 is 0.5 μm.

[0075] In addition, in this specific embodiment, the second contact electrode 42 includes four electrodes, namely the fifth to eighth upper contact electrodes 421, 422, 423, and 424. The four second contact electrodes 42 are disposed on the absorption layer 2, and their specific positions and dimensions are as follows:

[0076] The fifth upper contact electrode 421 is connected to the first upper contact electrode 411, with a width of 0.3 μm and a length of 3 μm. The distance between the fifth upper contact electrode 421 and the left edge of the absorption layer 2 is 5 μm, and the distance between the fifth upper contact electrode 421 and the upper edge of the absorption layer 2 is 1.2 μm.

[0077] The sixth upper contact electrode 422 is connected to the second upper contact electrode 412, with a width of 0.3 μm and a length of 3 μm. The distance between the sixth upper contact electrode 422 and the left edge of the absorption layer 2 is 8 μm, and the distance between the sixth upper contact electrode 422 and the upper edge of the absorption layer 2 is 1.2 μm.

[0078] The seventh upper contact electrode 423 is connected to the second and third upper contact electrodes 412 and 413, with a width of 0.3 μm and a length of 3 μm. The distance between the seventh upper contact electrode 423 and the left edge of the absorption layer 2 is 11 μm, and the distance between the seventh upper contact electrode 423 and the upper edge of the absorption layer 2 is 1.2 μm.

[0079] The eighth upper contact electrode 424 is connected to the second and third upper contact electrodes 412 and 413, with a width of 0.3 μm and a length of 3 μm. The distance between the eighth upper contact electrode 424 and the left edge of the absorption layer 2 is 14 μm, and the distance between the eighth upper contact electrode 424 and the upper edge of the absorption layer 2 is 1.2 μm.

[0080] Of course, in other specific embodiments of the present invention, the longer the absorption layer 2 is in the lateral direction, the more second contact electrodes 42 are provided.

[0081] In a first embodiment of the photodetector of the present invention, the upper contact electrode of the photodetector includes three first contact electrodes 41 and several second contact electrodes 42, depending on the intensity of the light field distribution. The first, second, and third upper contact electrodes 411, 412, and 413 are respectively placed laterally around the light field formed within the absorption layer 2, with a relatively large width to maximize the area of ​​the first contact electrodes 41. The second contact electrodes 42 are respectively placed longitudinally inside the light field formed within the absorption layer 2, with a smaller width to avoid light absorption.

[0082] Please refer to Figure 3 The diagram shown is a top view of the second embodiment of the photodetector of the present invention. The structure of the photodetector in this embodiment is basically the same as that in the first embodiment, and the same structures will not be described again here. Only the differences will be explained below.

[0083] In a second embodiment of the present invention, the incident light waveguide 3 includes a first incident light waveguide 31 and a second incident light waveguide 32. The first incident light waveguide 31 and the second incident light waveguide 32 are connected to both sides of the waveguide layer 13. The first incident light waveguide 31 and the second incident light waveguide 32 extend from the same side of the central axis toward the waveguide layer 13.

[0084] The first upper contact electrode 411 is disposed close to the first incident light waveguide 31, the third upper contact electrode 413 is disposed close to the second incident light waveguide 32, and the second upper contact electrode 412 is located between the first upper contact electrode 411 and the third upper contact electrode 413 in the direction of light propagation entering the absorption layer.

[0085] Please refer to Figure 4 The diagram shown is a top view of the third embodiment of the photodetector of the present invention. The structure of the photodetector in this embodiment is basically the same as that in the first embodiment, and the same structure will not be described again here. Only the differences will be explained below.

[0086] In the third embodiment of the present invention, similar to the second embodiment described above, the incident light waveguide 3 of the photodetector also includes a first incident light waveguide 31 and a second incident light waveguide 32, with the first incident light waveguide 31 and the second incident light waveguide 32 located on both sides of the absorption layer 2 in the lateral direction.

[0087] Unlike the second embodiment, in this third embodiment, the first incident waveguide 31 and the second incident waveguide 32 extend from different sides of the central axis toward the waveguide layer 13. Figure 4 For example, the first incident waveguide 31 located on the left extends from the lower side of the central axis toward the waveguide layer 13, and the second incident waveguide 32 located on the right extends from the upper side of the central axis toward the waveguide layer 13.

[0088] In this third embodiment, the upper contact electrode includes four electrically connected first contact electrodes 41. The first contact electrode 41 includes a first upper contact electrode 411, a second upper contact electrode 412, a third upper contact electrode 413, and a fourth upper contact electrode 414. The first upper contact electrode 412 and the fourth upper contact electrode 414 are respectively disposed close to the first incident light waveguide 31 and the second incident light waveguide 32. In the propagation direction of light entering the absorption layer 2, the second and third upper contact electrodes 412 and 413 are located between the first upper contact electrode 411 and the fourth upper contact electrode 414. The first upper contact electrode 411 and the fourth upper contact electrode 414 are positioned on opposite sides of the central axis. The second upper contact electrode 412 and the third upper contact electrode 413 are positioned on opposite sides of the central axis.

[0089] The photodetector of this invention can meet the requirements of low return loss and high responsivity. While ensuring low return loss, it minimizes the absorption of light signals by the metal electrode and maximizes the area of ​​the metal electrode, thereby improving the overall performance of the photodetector.

[0090] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A photodetector, characterized in that, include: Substrate; A waveguide layer disposed on the substrate; An absorption layer is disposed on the waveguide layer; A first doped region is formed within the waveguide layer; The second doped region is formed within the absorption layer and is located above the absorption layer; An incident optical waveguide, wherein the incident optical waveguide is connected to one side of the waveguide layer; A lower contact electrode, wherein the lower contact electrode is connected to the first doped region; The upper contact electrode is connected to the second doped region. The upper contact electrode includes at least three first contact electrodes that are electrically connected to each other. The extension direction of the at least three first contact electrodes is consistent with the propagation direction of the light entering the absorption layer from the incident light waveguide. The at least three first contact electrodes are distributed around the light field formed in the absorption layer. The absorption layer has a boundary line with the waveguide layer at a position adjacent to the incident light waveguide, and the extension direction of the incident light waveguide is inclined relative to the boundary line.

2. The photodetector as described in claim 1, characterized in that: The at least three first contact electrodes include a first upper contact electrode, a second upper contact electrode, and a third upper contact electrode. The first upper contact electrode is disposed close to the incident light waveguide, the third upper contact electrode is disposed away from the incident light waveguide, and the second upper contact electrode is located in the middle of the absorption layer and extends in the direction of light propagation entering the absorption layer.

3. The photodetector as described in claim 2, characterized in that: The upper contact electrode further includes a plurality of second contact electrodes, the first contact electrode and the second contact electrode are electrically connected, and the plurality of second contact electrodes are distributed along the propagation direction of light entering the absorption layer.

4. The photodetector as described in claim 3, characterized in that: The extension direction of the second contact electrode is perpendicular to the extension direction of the first contact electrode, and each first contact electrode is connected to at least one second contact electrode.

5. The photodetector as described in claim 3, characterized in that: The width of the first contact electrode in the direction perpendicular to the propagation direction of light entering the absorption layer is greater than the width of the second contact electrode in the propagation direction of light entering the absorption layer.

6. The photodetector as described in claim 3, characterized in that: The photodetector also has an electrode connecting leg and a connecting electrode connected to the electrode connecting leg, wherein the electrode connecting leg is connected to the first contact electrode.

7. The photodetector as described in claim 3, characterized in that: The second contact electrode is disposed between the first upper contact electrode and the second upper contact electrode, and extends in a direction perpendicular to the propagation direction of light entering the absorption layer.

8. The photodetector as described in claim 2, characterized in that: The second upper contact electrode and the first upper contact electrode are offset from each other in the direction of light propagation entering the absorption layer.

9. The photodetector as described in claim 2, characterized in that: In the direction of light propagation entering the absorption layer, the extension length of the second upper contact electrode is greater than that of the first upper contact electrode.

10. The photodetector as described in claim 2, characterized in that: The absorption layer has a central axis extending in the direction of light propagation entering the absorption layer, and the third upper contact electrode is located on the same side of the central axis as the first upper contact electrode.

11. The photodetector as described in claim 10, characterized in that: In the direction of light propagation entering the absorption layer, the extension length of the second upper contact electrode is greater than the extension length of the third upper contact electrode.

12. The photodetector as described in claim 10, characterized in that: In the direction of light propagation entering the absorption layer, the opposite ends of the third upper contact electrode are located within the extension range of the second upper contact electrode.

13. The photodetector as claimed in claim 1, characterized in that: The incident optical waveguide includes a first incident optical waveguide and a second incident optical waveguide, which are connected to both sides of the waveguide layer.

14. The photodetector as described in claim 13, characterized in that: The at least three first contact electrodes include a first upper contact electrode, a second upper contact electrode, and a third upper contact electrode. The first upper contact electrode is disposed close to the first incident light waveguide, the third upper contact electrode is disposed close to the second incident light waveguide, and the second upper contact electrode is located between the first upper contact electrode and the third upper contact electrode in the direction of light propagation entering the absorption layer.

15. The photodetector as described in claim 13, characterized in that: The upper contact electrode includes four electrically connected first contact electrodes, each comprising a first upper contact electrode, a second upper contact electrode, a third upper contact electrode, and a fourth upper contact electrode. The first and fourth upper contact electrodes are respectively disposed close to the first and second incident light waveguides. In the direction of light propagation entering the absorption layer, the second and third upper contact electrodes are located between the first and fourth upper contact electrodes. The first and fourth upper contact electrodes are respectively disposed on both sides of the central axis, and the second and third upper contact electrodes are respectively disposed on both sides of the central axis.

16. The photodetector according to any one of claims 1 to 15, characterized in that: The acute angle formed by the intersection of the extension direction of the incident optical waveguide and the boundary line ranges from 70° to 85°.

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