High-responsivity photoelectric detector chip
By designing a reflective structure on the photodetector chip, reflecting light to the photosensitive surface, the problem of the existing chip's responsiveness decreases when increasing the high-frequency bandwidth, achieving higher sensitivity, and providing higher-speed chip development It's possible.
Patent Information
- Application Number
- CN202420977038.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-08
- Publication Date
- 2025-02-07
- Estimated Expiration
- 2034-05-08
AI Technical Summary
While the existing photodetector chips increase the high-frequency bandwidth, their responsiveness decreases, resulting in poor sensitivity and difficult to meet the needs of higher transmission rate systems.
A high-responsive photodetector chip including a reflective structure is designed to reflect light to the photosensitive surface through a mirror surrounding the photosensitive surface, thereby improving the light collection ability.
Through the design of the reflective structure, the chip's responsiveness is improved on the photosensitive surface of the same area, achieving higher sensitivity, and providing possibilities for higher-speed chip development.
Smart Images
Figure CN222442198U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of optical communication, in particular to a high-responsivity photoelectric detector chip. Background Art
[0002] At present, in the field of optical communications, as the amount of data transmission increases exponentially, the speed requirements for the corresponding semiconductor laser chips and photodetector chips are getting higher and higher. Among them, the photodetector chips used as receiving optical chips, the industry has mass-produced 25GHz and 50GHz photodetector chips. The high-speed performance index of the receiving photodetector chip is currently characterized by sensitivity, which means the minimum optical power value required for light reception under the premise of ensuring the specified bit error rate. Sensitivity is mainly determined by the chip's responsiveness and high-frequency bandwidth. Responsivity characterizes the ability to convert received optical power into photocurrent under low-frequency conditions, and its unit is A / W. The high-frequency bandwidth characterizes the chip's ability to accurately convert high-frequency optical pulse signals into electrical signals. At present, in order to realize photodetector chips used in systems with higher transmission rates, it is necessary to increase the high-frequency bandwidth and responsiveness of this chip as much as possible. However, these two indicators are somewhat contradictory in photodetector chips: to improve the high-frequency bandwidth of photodetector chips, the capacitance of the chip needs to be reduced as much as possible without changing the material design. Therefore, the PIN or PN junction area needs to be reduced as much as possible during chip design (reduced junction area means that the area of the photosensitive surface for light collection also needs to be reduced). However, if the photosensitive surface is reduced, the chip's responsiveness will decrease. Therefore, in actual chip design, the size of the photosensitive surface has a restricted range.
[0003] To realize photodetector chips for systems with higher transmission rates, assuming that the material structure remains unchanged, the area of the photosensitive surface needs to be further reduced during chip design. However, when the area of the photosensitive surface is reduced to a certain extent, the sensitivity of the final photodetector chip becomes worse due to the significant decrease in responsiveness. Therefore, the size of the photosensitive surface of the existing design has a design limit. In addition, as the area of the photosensitive surface is reduced, the requirements for lithography overlay accuracy will be further increased, requiring a higher-precision lithography system and process level. Utility Model Content
[0004] The purpose of the utility model is to provide a high-responsivity photoelectric detector chip, which can at least solve some of the defects in the prior art.
[0005] To achieve the above objectives, the embodiment of the utility model provides the following technical solution: a high-responsiveness photodetector chip, comprising a main body and a reflective structure arranged on the main body, the top of the main body has a photosensitive surface, and the reflective structure is used to reflect light to the photosensitive surface.
[0006] Furthermore, the reflective structure includes at least one reflector arranged around the outer edge of the photosensitive surface.
[0007] Furthermore, along the upward direction of the photosensitive surface, the aperture of the reflector gradually expands.
[0008] Furthermore, the angle between the vertical section of the reflector and the horizontal line is between 45° and 90°.
[0009] Furthermore, the reflector is a ring-shaped reflector.
[0010] Furthermore, the body includes a substrate and an N-type indium phosphide layer, an indium gallium arsenide absorption layer and a P-type indium gallium arsenide layer stacked in sequence on the substrate, and the reflective structure includes a reflective portion for reflecting light, and the reflective portion is arranged on the P-type indium gallium arsenide layer.
[0011] Furthermore, the InGaAs absorption layer and the P-type InGaAs layer are flush with each other, the N-type InP layer, the InGaAs absorption layer and the P-type InGaAs layer form a step structure, and the reflective structure further includes a supporting portion connected to the reflective portion, the supporting portion is arranged along the step structure, and the bottom of the supporting portion falls on the N-type InP layer.
[0012] Furthermore, a first anti-reflection film is provided between the step structure and the reflective structure.
[0013] Furthermore, a P electrode is provided on the substrate, an N electrode is provided on the N-type indium phosphide layer, and a P-type contact electrode is provided on the P-type indium gallium arsenide layer.
[0014] Furthermore, the P electrode, the N electrode and the P-type contact electrode are all ring-shaped, a second anti-reflection film is provided in the ring area of the P-type contact electrode, and the ring area of the P-type contact electrode is the photosensitive surface; a third anti-reflection film is provided between the P electrode and the N electrode.
[0015] Compared with the prior art, the beneficial effects of the utility model are: a high-responsivity photodetector chip, which can reflect all the light near the photosensitive surface to the photosensitive surface by designing a reflective structure, thereby improving the ability to collect detection light, which is ultimately reflected in the chip performance, achieving improved chip responsiveness with the same area of photosensitive surface, and providing the possibility for the development of higher-speed and higher-sensitivity chips. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 A schematic diagram of a P-type indium gallium arsenide layer, an indium gallium arsenide absorption layer, an N-type indium phosphide layer and a P-type contact electrode of a method for preparing a high-responsivity photodetector chip provided in an embodiment of the utility model;
[0017] Figure 2 A schematic diagram of a method for preparing a high-responsivity photodetector chip provided by an embodiment of the utility model for forming a P-type InGaAs layer and an InGaAs absorption layer boss;
[0018] Figure 3 A schematic diagram of forming an N-type indium phosphide layer boss in a method for preparing a high-responsivity photodetector chip provided by an embodiment of the utility model;
[0019] Figure 4 A schematic diagram of a method for preparing a high-responsivity photodetector chip provided by an embodiment of the utility model for preparing an anti-reflection film on a photosensitive surface, a P electrode, and an N electrode;
[0020] Figure 5 A schematic diagram of a method for preparing a high-responsivity photodetector chip provided by an embodiment of the utility model;
[0021] In the figure markings: 1-P-type indium gallium arsenide layer; 2-indium gallium arsenide absorption layer; 3-N-type indium phosphide layer; 4-substrate; 5-P contact electrode; 60-first anti-reflection film; 61-second anti-reflection film; 62-third anti-reflection film; 7-P electrode; 8-N electrode; 9-annular reflector; 10-metal thin layer. DETAILED DESCRIPTION
[0022] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.
[0023] Embodiment 1:
[0024] See also Figure 5 , an embodiment of the utility model provides a method for preparing a high-responsiveness photodetector chip, including a main body and a reflective structure arranged on the main body, the top of the main body has a photosensitive surface, and the reflective structure is used to reflect light to the photosensitive surface. In this embodiment, by designing the reflective structure, all light near the photosensitive surface can be reflected to the photosensitive surface, thereby improving the ability to collect detection light, which is ultimately reflected in the chip performance, and the photosensitive surface of the same area improves the chip's responsiveness, providing the possibility of developing higher-speed and high-sensitivity chips. Specifically, since we use a reflective structure to collect the detection light, a smaller photosensitive surface can also obtain more detection light, and the chip's responsiveness will also be improved, thereby solving the contradiction between the high-frequency bandwidth and responsiveness of the chip in the prior art.
[0025] As an optimization solution of the embodiment of the utility model, please refer to Figure 5 , the reflective structure includes at least one reflector arranged around the outer edge of the photosensitive surface. In this embodiment, a reflector arranged around the outer edge of the photosensitive surface can be used to reflect light. The number of reflectors can be selected according to actual conditions. It can be a reflector, that is, the reflector can solve the problem of collecting detection light as shown in the figure of this embodiment, such as an annular reflector 9, or multiple reflectors can be put together in a ring shape for use. The reflectors can be connected or spaced apart. The purpose is to collect detection light for the photosensitive surface. This embodiment does not limit this. Preferably, a metal thin layer 10 is used at the reflector for reflection, for example, a thin layer made of Au. The metal thin layer 10 is not connected to the P electrode 7, the N electrode 8 and the P-type contact electrode.
[0026] To further optimize the above solution, please refer to Figure 5 The aperture of the reflector gradually expands along the upward direction of the photosensitive surface. The reflector is in the form of a trumpet-shaped gradually expanding form, and its tilt angle θ can be between 45° and 90°. The specific angle selection can be determined after simulation during chip design.
[0027] As an optimization solution of the embodiment of the utility model, please refer to Figure 5 The body includes a substrate 4 and an N-type indium phosphide layer 3, an indium gallium arsenide absorption layer 2 and a P-type indium gallium arsenide layer 1 which are sequentially stacked on the substrate 4. The reflective structure includes a reflective portion for reflecting light, and the reflective portion is arranged on the P-type indium gallium arsenide layer 1. Preferably, the indium gallium arsenide absorption layer 2 and the P-type indium gallium arsenide layer 1 are flush with each other on the side, and the N-type indium phosphide layer 3, the indium gallium arsenide absorption layer 2 and the P-type indium gallium arsenide layer 1 form a step structure. The reflective structure also includes a support portion connected to the reflective portion, and the support portion is arranged along the step structure, and the bottom of the support portion falls on the N-type indium phosphide layer 3. In this embodiment, the reflective structure can be divided into two parts, namely, a reflective portion and a support portion, wherein the reflective portion is used to reflect light, and the support portion is relatively extended, and its bottom is arranged on the N-type indium phosphide layer 3, and can be regarded as the support portion of the reflective portion. The reflective portion needs to have an inclined reflector to reflect light. The supporting part only needs to ensure the stability of the reflective part. Figure 5Only one of the structural forms is shown, and the outer side of the support part is also an inclined surface, and a trapezoidal structure is adopted to improve stability. Of course, other structural forms are also feasible, and this embodiment does not limit this. In the main body, the width of the P-type indium gallium arsenide and the indium gallium arsenide absorption layer 2 is the same, but the thickness is different. The two can be regarded as bosses designed on the N-type indium phosphide layer 3, so that the boss forms a step structure with the N-type indium phosphide layer 3, and the entire reflective structure is arranged based on the step structure. Preferably, a first anti-reflection film 60 is also provided between the step structure and the reflective structure. After the first anti-reflection film 60 is provided, the reflective structure is separated from the N-type indium phosphide layer 3.
[0028] As an optimization solution of the embodiment of the utility model, please refer to Figure 5 , a P electrode 7 is provided on the substrate 4, an N electrode 8 is provided on the N-type indium phosphide layer 3, and a P-type contact electrode is provided on the P-type indium gallium arsenide layer 1. The P electrode 7, the N electrode 8 and the P-type contact electrode are all in annular shape, a second anti-reflection film 61 is provided in the annular region of the P-type contact electrode, and the annular region of the P-type contact electrode is the photosensitive surface; a third anti-reflection film 62 is provided between the P electrode 7 and the N electrode 8. In this embodiment, several electrode PADs are made to open the electrode contact between the P and N electrodes 8. The above-mentioned photosensitive surface is formed in the surrounding area of the P-type contact electrode, so the reflector is also arranged along the outer edge of the P-type contact electrode to reflect the detection light into the photosensitive surface.
[0029] As an optimization solution of the embodiment of the utility model, please refer to Figure 5 The reflective structure is made of photoresist, and a metal thin layer 10 is arranged on the inclined surface next to the photosensitive surface to form the reflective structure. The reflective structure is made of photoresist, which is convenient for manufacturing and molding, and the required structural form is manufactured to ensure the reflective angle and stability of the light-emitting structure.
[0030] Embodiment 2:
[0031] See also Figures 1 to 5, the utility model embodiment provides a method for preparing a high-responsivity photodetector chip, which is used to make the above-mentioned chip, so the detailed features of the above-mentioned chip can be used in this embodiment. The method includes the following steps: S1, making an epitaxial structure; S2, photolithography, etching and corrosion of the epitaxial structure to obtain a chip body; S3, making a reflective structure on the chip body, and the reflective structure reflects the light around the photosensitive surface of the chip body to the photosensitive surface. In this embodiment, by making a reflective structure, all the light near the photosensitive surface can be reflected to the photosensitive surface, which improves the ability to collect detection light, and is ultimately reflected in the chip performance, achieving the same area of the photosensitive surface to improve the chip's responsiveness, and providing the possibility of realizing the development of higher-speed and high-sensitivity chips. Specifically, since we use a reflective structure to collect the detection light, a smaller photosensitive surface can also obtain more detection light, and the chip's responsiveness will also be improved, thereby solving the contradiction between the high-frequency bandwidth and responsiveness of the chip in the prior art.
[0032] The following is the specific preparation method:
[0033] First, an N-InP layer (N-type indium phosphide layer 3), an InGaAs absorption layer (indium gallium arsenide absorption layer 2), a P-InGaAs layer (P-type indium gallium arsenide layer 1), and a P contact layer are sequentially grown on a substrate 4 by using MOCVD;
[0034] Then, using photolithography technology, a phosphoric acid-based etching solution is used to etch the P contact layer into a ring shape, and a P electrode contact 5 is made on the contact ring. Figure 1 ;
[0035] Then, a mesa mask layer is grown using PECVD, and the mask layer on the mesa is retained using photolithography and etching processes. The area outside the mesa mask layer is then etched to the N-InP layer to form the mesa of the InGaAs absorption layer and the P-InGaAs layer, and then the mesa mask layer is removed. Figure 2 ;
[0036] Then, photolithography technology is used to etch the N-InP layer into a mesa using a phosphoric acid etching solution. Figure 3 ;
[0037] Then, a passivation layer and a photosensitive surface anti-reflection film 6 are grown using PECVD, and the P and N electrode contacts are opened using photolithography and etching processes, and a P electrode pad is made on the substrate 4, and an N electrode pad is made on the N-InP layer, as shown in FIG. Figure 4 ;
[0038] Then, photolithography and etching techniques are used to make an annular reflector on the InGaAs absorption layer and the table surface of the P-InGaAs layer using a 3-25 μm thick BCB photoresist. The angle of the reflective slope relative to the horizontal direction is 45-90° (the specific angle selection can be determined after simulation during chip design). Then, a metal thin layer 10 is made on the reflective slope as the reflective surface of the reflector, and the light around the photosensitive surface is reflected to the photosensitive surface through the transmitting mirror. Figure 5 ; Note that the Au metal thin layer 10 cannot be connected to the P contact electrode 5, the P electrode 7 and the -N electrode 8.
[0039] The solution involved in the utility model can be applied to all photoelectric detector chips with photosensitive surface structures.
[0040] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A high-responsivity photodetector chip, comprising a body, characterized in that: It also includes a reflective structure arranged on the main body, the top of the main body has a photosensitive surface, and the reflective structure is used to reflect light to the photosensitive surface.
2. The high-responsivity photodetector chip according to claim 1, characterized in that: The reflective structure includes at least one reflector arranged around the outer edge of the photosensitive surface.
3. The high-responsivity photodetector chip according to claim 2, characterized in that: Along the upward direction of the photosensitive surface, the aperture of the reflector gradually expands.
4. The high-responsivity photodetector chip according to claim 3, characterized in that: The included angle between the vertical section of the reflector and the horizontal line is between 45° and 90°.
5. The high-responsivity photodetector chip according to claim 2, characterized in that: The reflector is a ring-shaped reflector.
6. The high-responsivity photodetector chip according to claim 1, characterized in that: The body includes a substrate and an N-type indium phosphide layer, an indium gallium arsenide absorption layer and a P-type indium gallium arsenide layer stacked in sequence on the substrate. The reflective structure includes a reflective portion for reflecting light, and the reflective portion is arranged on the P-type indium gallium arsenide layer.
7. The high-responsivity photodetector chip according to claim 6, characterized in that: The InGaAs absorption layer is flush with the side surfaces of the P-type InGaAs layer, the N-type InP layer, the InGaAs absorption layer and the P-type InGaAs layer form a step structure, and the reflective structure further includes a supporting portion connected to the reflective portion, the supporting portion is arranged along the step structure, and the bottom of the supporting portion falls on the N-type InGaAs layer.
8. The high-responsivity photodetector chip according to claim 7, characterized in that: A first anti-reflection film is also provided between the step structure and the reflective structure.
9. The high-responsivity photodetector chip according to claim 6, characterized in that: A P electrode is arranged on the substrate, an N electrode is arranged on the N-type indium phosphide layer, and a P-type contact electrode is arranged on the P-type indium gallium arsenide layer.
10. The high-responsivity photodetector chip according to claim 9, characterized in that: The P electrode, the N electrode and the P-type contact electrode are all ring-shaped, a second anti-reflection film is provided in the ring area of the P-type contact electrode, and the ring area of the P-type contact electrode is the photosensitive surface; a third anti-reflection film is provided between the P electrode and the N electrode.