An InGaN / PdO heterojunction self-powered visible light photodetector and its preparation method
By epitaxially growing PdO on the InGaN layer to construct an InGaN/PdO heterojunction, a high-quality natural PN junction is formed, which solves the problem of poor quality of InGaN films, achieves efficient carrier separation and detector self-powering characteristics, enhances the detector's responsiveness and detection efficiency, and promotes the commercialization of InGaN-based detectors.
Patent Information
- Application Number
- CN202311424740.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-10-31
- Publication Date
- 2025-09-30
- Estimated Expiration
- 2043-10-31
AI Technical Summary
The existing InGaN films are of poor quality and contain a large number of defects and stresses, which severely restrict the responsiveness, response speed and detection rate of photodetectors, and limit the commercialization process of InGaN-based detectors.
By epitaxially growing PdO on the InGaN layer to construct an InGaN/PdO heterojunction, a high-quality natural PN junction is formed, generating a built-in electric field and a high-speed carrier migration channel. The film quality is optimized by combining low-temperature PLD and high-temperature MOCVD processes, and an Al2O3 insulating layer is set to ensure correct electrode contact to achieve self-powered characteristics.
The detector's response characteristics and self-powering capability to the visible light band have been greatly enhanced, efficient carrier separation and detection have been achieved, the device's bandgap matching to the visible light band has been optimized, and the response and detection efficiency have been improved.
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Abstract
Description
Technical Field
[0001] The present invention relates to the field of visible light detectors, and in particular to an InGaN / PdO heterojunction self-powered visible light photoelectric detector and a preparation method thereof. Background Art
[0002] Visible light communication plays a vital role in the 6G space-ground integrated communication network. However, traditional Si-based visible light detectors are no longer suitable for the development of visible light communication due to disadvantages such as high noise and the need for expensive filtering systems during use. Group III nitride semiconductor materials have a wide bandgap, stable chemical properties, and high carrier mobility, which makes them very suitable for the preparation of optoelectronic devices.
[0003] As a third-generation semiconductor material with adjustable composition, InGaN can achieve precise control of its bandgap from 0.7eV to 3.4eV through precise composition regulation. This variable bandgap allows for selective detection of visible light without the need for expensive and complex filtering systems. Its excellent and stable physical and chemical properties make it a popular choice for photodetectors. By combining InGaN with other semiconductor materials to form a type II heterojunction, the built-in electric field generated by the heterojunction can be used to achieve self-power, reducing device size and energy consumption. The realization of high-quality, self-powered heterojunction detectors has become a hot topic of research.
[0004] Although researchers have conducted extensive research on InGaN photodetectors, their commercialization remains a long way off. A major obstacle hindering the commercialization of InGaN-based detectors is the poor quality of current InGaN films, which suffer from numerous defects, stresses, and phase separation. The presence of numerous defects and stresses in InGaN films is primarily due to the large lattice mismatch between InGaN and the substrate, which results in widespread presence of defects and stresses within the epitaxial film. Phase separation stems from the lattice mismatch between InN and GaN. To minimize system energy, In easily segregates and aggregates, leading to phase separation. Defects within the film act as carrier recombination centers, while stress and phase separation interfere with carrier transport. This severely limits the responsivity, response speed, and detectivity of InGaN-based photodetectors. Developing new epitaxial processes to achieve high-quality InGaN film growth and construct heterojunction detectors is an effective means of overcoming these limitations. Summary of the Invention
[0005] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the purpose of the present invention is to provide an InGaN / PdO heterojunction self-powered visible light photodetector. By constructing an InGaN / PdO heterojunction by epitaxially growing PdO on an InGaN layer, a high-quality natural PN junction is formed, generating a built-in electric field and a high-speed carrier migration channel, enabling the detector to detect in the visible light band, while achieving efficient carrier separation and the self-powered characteristics of the detector, greatly enhancing the detector's response characteristics to the visible light band.
[0006] Another object of the present invention is to provide a method for preparing an InGaN / PdO heterojunction self-powered visible light photodetector.
[0007] The purpose of the present invention is achieved through the following technical solutions:
[0008] An InGaN / PdO heterojunction self-powered visible light photodetector, comprising a substrate, a buffer layer, an InGaN layer, a PdO layer, an Al2O3 insulating layer, a first electrode layer, and a second electrode layer stacked sequentially from bottom to top; the first electrode layer and the second electrode layer are respectively disposed on the PdO layer and the InGaN layer; the InGaN layer and the PdO layer form an InGaN / PdO heterojunction;
[0009] The thickness of the InGaN layer is 100-200 nm, and the thickness of the PdO layer is 20-60 nm.
[0010] Preferably, the InGaN / PdO heterojunction self-powered visible light photodetector further includes an Al2O3 insulating layer, which is arranged between the InGaN layer and the PdO layer; the PdO layer covers part of the surface of the InGaN layer, the surface of the Al2O3 insulating layer and the side of the Al2O3 insulating layer.
[0011] Preferably, the thickness of the Al2O3 insulating layer is 120-160 nm.
[0012] Preferably, the first electrode layer is an Au metal layer with a thickness of 120 to 240 nm.
[0013] Preferably, the second electrode layer is a Ti / Au metal layer; the Ti / Au metal layer includes a Ti metal layer and an Au metal layer stacked from bottom to top, the thickness of the Ti metal layer is 30 to 60 nm; the thickness of the Au metal layer is 90 to 180 nm.
[0014] Preferably, the buffer layer includes an AlN layer, an AlGaN layer and a GaN layer stacked sequentially from bottom to top; the thicknesses of the AlN layer, the AlGaN layer and the GaN layer are 200-250 nm, 300-500 nm and 1-4 μm respectively.
[0015] The method for preparing the InGaN / PdO heterojunction self-powered visible light photodetector comprises the following steps:
[0016] (1) A buffer layer is grown on the substrate using a low-temperature PLD method, and then an InGaN layer is grown on the buffer layer using a high-temperature MOCVD method;
[0017] (2) Performing photolithography on the InGaN layer, performing photoresist coating, drying, exposure, development and oxygen ion treatment on the surface of the InGaN layer, and depositing a Pd thin film on the window opened by the photolithography by evaporation;
[0018] (3) Placing the epitaxial wafer with the deposited Pd film in an oxygen-permeable CVD tube furnace, and preparing an epitaxial PdO layer by thermally assisted oxidation to form an InGaN / PdO heterojunction functional layer;
[0019] (4) Perform photolithography of the second electrode position window on the InGaN layer to determine the shape and position of the electrode on the InGaN layer, and evaporate the Ti / Au electrode layer on the InGaN layer through the evaporation process; perform photolithography of the first electrode position window on the PdO layer, and evaporate the Au electrode layer on the PdO layer through the evaporation process.
[0020] Preferably, in step (2), after the steps of coating, drying, exposing, developing and oxygen ion treatment on the surface of the InGaN layer and before the step of depositing a Pd thin film on the window opened by photolithography by evaporation, the following steps are further performed:
[0021] An Al2O3 insulating layer is evaporated on the InGaN layer through an evaporation process, and then windows are opened on the InGaN layer and the Al2O3 insulating layer through photolithography.
[0022] Preferably, in step (3), the oxygen flow rate of the CVD tube furnace is 50-60 sccm, the tube pressure is 50-55 mTorr, the heating rate is 5°C / s, the termination temperature is 430-450°C, and the holding time is 6-6.5 h.
[0023] Preferably, in step (2), the evaporation rate of the Pd film is 5 to 9 nm / min.
[0024] Preferably, the temperatures for epitaxially growing the AlN layer, the AlGaN layer and the GaN layer from bottom to top on the substrate using the low-temperature PLD method are 400-500° C., 520-600° C. and 600-750° C. respectively.
[0025] Preferably, the temperature for growing the InGaN layer on the buffer layer using the high-temperature MOCVD method is 800-1200°C.
[0026] Preferably, the coating speed is 1500-3000 r / s, the drying time is 85-95 s, the exposure time is 60-80 s, the development time is 10-60 s, and the oxygen ion treatment time is 2-4 min.
[0027] Preferably, the evaporation rate of the Al2O3 insulating layer and the metal layer electrode is 5 to 9 nm / min.
[0028] Compared with the prior art, the present invention has the following advantages and beneficial effects:
[0029] (1) The InGaN / PdO heterojunction self-powered visible light photodetector of the present invention forms a high-quality natural PN junction by epitaxially growing PdO on an InGaN layer, generating a built-in electric field and a high-speed carrier migration channel, enabling the detector to detect visible light bands, while achieving efficient carrier separation and the self-powered characteristics of the detector, greatly enhancing the response characteristics, responsivity and self-powered characteristics of the detector to the visible light band.
[0030] (2) The InGaN / PdO heterojunction self-powered visible light photodetector of the present invention achieves bandgap matching of the heterojunction to the visible light band by optimizing the thickness ratio of the InGaN layer and the PdO layer, thereby realizing narrowband detection of the visible light band; on this basis, the device parameters, InGaN / PdO thickness ratio and preparation process of the detector are optimized and designed, effectively improving the device's response capability to light waves.
[0031] (3) The InGaN / PdO heterojunction self-powered visible light photodetector of the present invention ensures that the two electrodes are in contact only with the InGaN layer and the PdO layer, respectively, by providing an Al2O3 insulating layer between the InGaN layer and the PdO layer, thereby preventing the electrode located on the PdO from contacting the InGaN layer below through the PdO. This ensures that when the detector is working, the heterojunction effect can be fully utilized, so that electrons and holes are transmitted from the InGaN layer and the PdO layer, respectively.
[0032] (4) The preparation method of the InGaN / PdO heterojunction self-powered visible light photodetector of the present invention uses an AlN / AlGaN / GaN buffer layer designed by low-temperature PLD high-quality epitaxy to avoid direct contact between the InGaN layer and the substrate, thereby effectively alleviating the lattice mismatch problem between the InGaN layer and the substrate.
[0033] (5) The preparation method of the InGaN / PdO heterojunction self-powered visible light photodetector of the present invention uses a high-temperature MOCVD method to epitaxially grow an InGaN layer on a buffer layer, and uses high temperature to promote the merging of growth islands, effectively reducing defects, releasing stress, and inhibiting phase separation, thereby obtaining a high-quality InGaN film. BRIEF DESCRIPTION OF THE DRAWINGS
[0034] Figure 1 This is a schematic cross-sectional view of the structure of the InGaN / PdO heterojunction self-powered visible light photodetector provided by the present invention.
[0035] Figure 2 This is a schematic diagram of the top view of the structure of the InGaN / PdO heterojunction self-powered visible light photodetector provided by the present invention.
[0036] Figure 3 This is a spectral response curve of the InGaN / PdO heterojunction self-powered visible light photodetector obtained in Example 1 of the present invention.
[0037] Figure 4 This is a light-dark current comparison curve of the InGaN / PdO heterojunction self-powered visible light photodetector obtained in Example 1 of the present invention. DETAILED DESCRIPTION
[0038] The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto.
[0039] Example 1
[0040] This embodiment provides an InGaN / PdO heterojunction self-powered visible light photodetector, such as Figure 1 As shown, it includes, from bottom to top, a substrate 1, a buffer layer 2, and an InGaN layer 3; an Al2O3 layer 4 that acts as an isolation layer; a PdO layer 5 that forms a heterojunction with the InGaN; and electrode layers 6 and 7 located on the PdO layer 5 and the InGaN layer 3, respectively. The Al2O3 layer 4 is disposed between the InGaN layer 3 and the PdO layer 5; and the PdO layer covers part of the surface of the InGaN layer 3, the surface of the Al2O3 layer, and the sides of the Al2O3 layer. The buffer layer 2 is composed of an AlN layer, an AlGaN layer, and a GaN layer arranged from bottom to top. The InGaN layer 3 is epitaxially grown on the buffer layer 2 and has a thickness of 100 nm. The PdO layer 5 is deposited on the InGaN layer by evaporation and CVD thermal oxidation and has a thickness of 20 nm.
[0041] Substrate 1 is a sapphire substrate; the thicknesses of the AlN layer, AlGaN layer and GaN layer are 200 nm, 300 nm and 1 μm respectively, and the thickness of the insulating layer Al2O3 is 120 nm.
[0042] like Figure 2 As shown, the shape of the electrode is a rectangular electrode, the electrode layer 6 is an Au metal layer with a thickness of 120nm, and the electrode layer 7 is a Ti / Au metal layer. The Ti / Au metal layer is composed of a Ti metal layer with a thickness of 30nm and an Au metal layer with a thickness of 90nm arranged from bottom to top.
[0043] This embodiment also provides a method for preparing the InGaN / PdO heterojunction self-powered visible light photodetector, comprising the following steps:
[0044] (1) A buffer layer was grown on the substrate using a low-temperature PLD method, and then an InGaN layer was grown on the buffer layer using a high-temperature MOCVD method. The temperatures for epitaxial growth of the AlN layer, AlGaN layer, GaN layer, and InGaN layer were 400°C, 520°C, 600°C, and 800°C, respectively.
[0045] (2) The surface of the InGaN layer is coated, dried, exposed, developed and treated with oxygen ions to determine the position and shape of the insulating layer, and an Al2O3 layer is evaporated on the InGaN layer through an evaporation process.
[0046] (3) The InGaN layer and the Al2O3 layer were coated, dried, exposed, developed and treated with oxygen ions to determine the evaporation position of the Pd film. The Pd metal was evaporated to the window position. The epitaxial wafer with the Pd film deposited was placed in an oxygen-permeable CVD tube furnace. The epitaxial PdO layer was prepared by thermal heating. The oxygen flow rate of the CVD tube furnace was 50 sccm, the tube pressure was 50 mTorr, the heating rate was 5°C / s, the end temperature was 450°C, and the holding time was 6 h.
[0047] (4) The InGaN layer and the PdO layer are coated, dried, exposed, developed, and treated with oxygen ions to determine the shape and position of the electrode on the InGaN layer. A Ti / Au electrode layer is then evaporated on the InGaN layer. A second photolithography process is then performed to determine the shape and position of the electrode on the PdO layer. An Au electrode layer is then evaporated on the PdO layer.
[0048] (5) The coating speed used in steps (2) to (4) is 1500 r / s, the drying time is 85 s, the exposure time is 60 s, the development time is 10 s, the oxygen ion treatment time is 2 min, and the evaporation rate used in the evaporation process is 5 nm / min.
[0049] Figure 3 This is a spectral response curve of the InGaN / PdO heterojunction self-powered visible light photodetector obtained in this embodiment. It can be seen from the figure that the obtained detector obtains a narrowband response in the visible light band near 433nm, indicating that the detector can achieve high-sensitivity detection in the visible light band.
[0050] Figure 4This is a light-dark current comparison curve of the InGaN / PdO heterojunction self-powered visible light photodetector obtained in this embodiment. It can be seen from the figure that the obtained detector has extremely low dark current and large photocurrent, and obtains a self-powered characteristic of 15nA under 0V bias, indicating that the detector has the ability to be self-powered.
[0051] Example 2
[0052] This embodiment provides an InGaN / PdO heterojunction self-powered visible light photodetector, such as Figure 1 As shown, it includes, from bottom to top, a substrate 1, a buffer layer 2, and an InGaN layer 3; an Al2O3 layer 4 for isolation; a PdO layer 5 forming a heterojunction with the InGaN; and electrode layers 6 and 7 located on the PdO layer 5 and the InGaN layer 3, respectively. The Al2O3 layer 4 is disposed between the InGaN layer 3 and the PdO layer 5; and the PdO layer covers part of the surface of the InGaN layer 3, the surface of the Al2O3 layer, and the sides of the Al2O3 layer. The buffer layer 2 is composed of an AlN layer, an AlGaN layer, and a GaN layer arranged from bottom to top. The InGaN layer 3 is epitaxially grown on the buffer layer 2 and has a thickness of 150nm. The PdO layer 5 is deposited on the InGaN layer by evaporation and CVD thermal oxidation and has a thickness of 40nm.
[0053] Substrate 1 is a sapphire substrate; the thicknesses of the AlN layer, AlGaN layer and GaN layer are 220 nm, 400 nm and 3 μm respectively, and the thickness of the insulating layer Al 2 O 3 is 140 nm.
[0054] like Figure 2 As shown, the shape of the electrode is a rectangular electrode, the electrode layer 6 is an Au metal layer with a thickness of 180nm, and the electrode layer 7 is a Ti / Au metal layer, which is composed of a Ti metal layer with a thickness of 40nm and an Au metal layer with a thickness of 140nm arranged from bottom to top.
[0055] This embodiment also provides a method for preparing the InGaN / PdO heterojunction self-powered visible light photodetector, comprising the following steps:
[0056] (1) A buffer layer was grown on the substrate using a low-temperature PLD method, and then an InGaN layer was grown on the buffer layer using a high-temperature MOCVD method. The temperatures for epitaxial growth of the AlN layer, AlGaN layer, GaN layer, and InGaN layer were 450°C, 560°C, 700°C, and 1000°C, respectively.
[0057] (2) The surface of the InGaN layer is coated, dried, exposed, developed and treated with oxygen ions to determine the position and shape of the insulating layer, and an Al2O3 layer is evaporated on the InGaN layer through an evaporation process.
[0058] (3) The InGaN layer and the Al2O3 layer were coated, dried, exposed, developed and treated with oxygen ions to determine the evaporation position of the Pd film. The Pd metal was evaporated to the window position. The epitaxial wafer with the Pd film deposited was placed in an oxygen-permeable CVD tube furnace. The epitaxial PdO layer was prepared by thermal heating. The oxygen flow rate of the CVD tube furnace was 55 sccm, the tube pressure was 52 mTorr, the heating rate was 5°C / s, the end temperature was 450°C, and the holding time was 6 h.
[0059] (4) The InGaN layer and the PdO layer are coated, dried, exposed, developed, and treated with oxygen ions to determine the shape and position of the electrode on the InGaN layer. A Ti / Au electrode layer is then evaporated on the InGaN layer. A second photolithography process is then performed to determine the shape and position of the electrode on the PdO layer. An Au electrode layer is then evaporated on the PdO layer.
[0060] (5) The coating speed used in steps (2) to (4) is 2000 r / s, the drying time is 90 s, the exposure time is 70 s, the development time is 40 s, the oxygen ion treatment time is 3 min, and the evaporation rate used in the evaporation process is 7 nm / min.
[0061] The detector obtained in this embodiment has extremely low dark current and large photocurrent, and obtains self-powered characteristics under a bias voltage of 0V, indicating that the detector has the ability to be self-powered.
[0062] Example 3
[0063] This embodiment provides an InGaN / PdO heterojunction self-powered visible light photodetector, such as Figure 1 As shown, it includes, from bottom to top, a substrate 1, a buffer layer 2, and an InGaN layer 3; an Al2O3 layer 4 for isolation; a PdO layer 5 forming a heterojunction with the InGaN; and electrode layers 6 and 7 located on the PdO layer 5 and the InGaN layer 3, respectively. The Al2O3 layer 4 is disposed between the InGaN layer 3 and the PdO layer 5; and the PdO layer covers part of the surface of the InGaN layer 3, the surface of the Al2O3 layer, and the sides of the Al2O3 layer. The buffer layer 2 is composed of an AlN layer, an AlGaN layer, and a GaN layer arranged from bottom to top. The InGaN layer 3 is epitaxially grown on the buffer layer 2 and has a thickness of 200nm. The PdO layer 5 is deposited on the InGaN layer by evaporation and CVD thermal oxidation and has a thickness of 60nm.
[0064] Substrate 1 is a sapphire substrate; the thicknesses of the AlN layer, AlGaN layer, and GaN layer are 250 nm, 500 nm, and 4 μm, respectively; and the thickness of the insulating layer Al 2 O 3 is 160 nm.
[0065] like Figure 2 As shown, the shape of the electrode is a rectangular electrode, the electrode layer 6 is an Au metal layer with a thickness of 240nm, and the electrode layer 7 is a Ti / Au metal layer, which is composed of a Ti metal layer with a thickness of 60nm and an Au metal layer with a thickness of 180nm arranged from bottom to top.
[0066] This embodiment also provides a method for preparing the InGaN / PdO heterojunction self-powered visible light photodetector, comprising the following steps:
[0067] (1) A buffer layer was grown on the substrate using a low-temperature PLD method, and then an InGaN layer was grown on the buffer layer using a high-temperature MOCVD method. The temperatures for epitaxial growth of the AlN layer, AlGaN layer, GaN layer, and InGaN layer were 500°C, 600°C, 750°C, and 1200°C, respectively.
[0068] (2) The surface of the InGaN layer is coated, dried, exposed, developed and treated with oxygen ions to determine the position and shape of the insulating layer, and an Al2O3 layer is evaporated on the InGaN layer through an evaporation process.
[0069] (3) The InGaN layer and the Al2O3 layer were coated, dried, exposed, developed and treated with oxygen ions to determine the evaporation position of the Pd film. The Pd metal was evaporated to the window position. The epitaxial wafer with the Pd film deposited was placed in an oxygen-permeable CVD tube furnace. The epitaxial PdO layer was prepared by thermal heating. The oxygen flow rate of the CVD tube furnace was 60 sccm, the tube pressure was 55 mTorr, the heating rate was 5°C / s, the end temperature was 450°C, and the holding time was 6 h.
[0070] (4) The InGaN layer and the PdO layer are coated, dried, exposed, developed, and treated with oxygen ions to determine the shape and position of the electrode on the InGaN layer. A Ti / Au electrode layer is then evaporated on the InGaN layer. A second photolithography process is then performed to determine the shape and position of the electrode on the PdO layer. An Au electrode layer is then evaporated on the PdO layer.
[0071] (5) The coating speed used in steps (2) to (4) is 3000 r / s, the drying time is 95 s, the exposure time is 80 s, the development time is 60 s, the oxygen ion treatment time is 4 min, and the evaporation rate used in the evaporation process is 9 nm / min.
[0072] The detector obtained in this embodiment has extremely low dark current and large photocurrent, and obtains self-powered characteristics under a bias voltage of 0V, indicating that the detector has the ability to be self-powered.
[0073] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.
Claims
1. An InGaN / PdO heterojunction self-powered visible light photodetector, characterized in that: The invention comprises a substrate, a buffer layer, an InGaN layer, a PdO layer, an Al2O3 insulating layer, a first electrode layer and a second electrode layer stacked in sequence from bottom to top; the first electrode layer and the second electrode layer are respectively arranged on the PdO layer and the InGaN layer; the InGaN layer and the PdO layer form an InGaN / PdO heterojunction; The thickness of the InGaN layer is 100-200 nm, and the thickness of the PdO layer is 20-60 nm; The Al2O3 insulating layer is provided between the InGaN layer and the PdO layer; the PdO layer covers a portion of the surface of the InGaN layer, the surface of the Al2O3 insulating layer and one side surface of the Al2O3 insulating layer; The buffer layer includes an AlN layer, an AlGaN layer, and a GaN layer stacked sequentially from bottom to top; the thicknesses of the AlN layer, the AlGaN layer, and the GaN layer are 200-250 nm, 300-500 nm, and 1-4 μm, respectively.
2. The InGaN / PdO heterojunction self-powered visible light photodetector according to claim 1, characterized in that: The thickness of the Al2O3 insulating layer is 120-160 nm.
3. The InGaN / PdO heterojunction self-powered visible light photodetector according to claim 1, characterized in that: The first electrode layer is an Au metal layer with a thickness of 120-240 nm.
4. The InGaN / PdO heterojunction self-powered visible light photodetector according to claim 1, characterized in that: The second electrode layer is a Ti / Au metal layer; the Ti / Au metal layer includes a Ti metal layer and an Au metal layer stacked from bottom to top, the thickness of the Ti metal layer is 30-60 nm; the thickness of the Au metal layer is 90-180 nm.
5. The method for preparing the InGaN / PdO heterojunction self-powered visible light photodetector according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) A buffer layer is grown on the substrate using a low-temperature PLD method, and then an InGaN layer is grown on the buffer layer using a high-temperature MOCVD method; The buffer layer is grown on the substrate using a low-temperature PLD method, specifically: an AlN layer, an AlGaN layer and a GaN layer are epitaxially grown on the substrate from bottom to top using a low-temperature PLD method, at temperatures of 400-500° C., 520-600° C. and 600-750° C., respectively; The method of growing the InGaN layer by high-temperature MOCVD specifically comprises: growing the InGaN layer on the buffer layer by high-temperature MOCVD at a temperature of 800-1200° C.; (2) Perform photolithography on the InGaN layer, perform surface coating, drying, exposure, development and oxygen ion treatment on the InGaN layer, evaporate the Al2O3 insulating layer on the InGaN layer by evaporation, then open windows on the InGaN layer and the Al2O3 insulating layer by photolithography, and deposit the Pd thin film on the window opened by photolithography by evaporation; (3) Placing the epitaxial wafer with the deposited Pd film in an oxygen-permeable CVD tube furnace, and preparing an epitaxial PdO layer by thermally assisted oxidation to form an InGaN / PdO heterojunction functional layer; (4) Perform photolithography of the second electrode position window on the InGaN layer to determine the shape and position of the electrode on the InGaN layer, and evaporate the Ti / Au electrode layer on the InGaN layer through the evaporation process; perform photolithography of the first electrode position window on the PdO layer, and evaporate the Au electrode layer on the PdO layer through the evaporation process.
6. The method for preparing the InGaN / PdO heterojunction self-powered visible light photodetector according to claim 5, characterized in that: In step (3), the oxygen flow rate of the CVD tube furnace is 50-60 sccm, the tube pressure is 50-55 mTorr, the heating rate is 5°C / s, the end temperature is 430-450°C, and the holding time is 6-6.5 h.
7. The method for preparing the InGaN / PdO heterojunction self-powered visible light photodetector according to claim 5, characterized in that: In step (2), the evaporation rate of the Pd film is 5~9 nm / min.