Gallium nitride / molybdenum disulfide heterojunction photodetector and preparation method
By using a gallium nitride/molybdenum disulfide heterojunction structure, combined with conventional photolithography and transfer techniques, the lattice mismatch problem between three-dimensional and two-dimensional materials was solved, enabling low-cost and high-efficiency fabrication of photodetectors and improving device performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHONGBEI UNIV
- Filing Date
- 2026-03-13
- Publication Date
- 2026-05-12
AI Technical Summary
Traditional ultraviolet photodetectors are based on wide-bandgap semiconductor materials, which are costly and have complex manufacturing processes. The combination of three-dimensional and two-dimensional materials results in lattice mismatch, leading to an increase in interface defects and affecting device performance.
A gallium nitride/molybdenum disulfide heterojunction structure is adopted. By depositing a passivation layer on the surface of the gallium nitride layer and etching openings, the molybdenum disulfide film is transferred to direct contact with the gallium nitride layer. The van der Waals forces are used to bond the materials together, avoiding lattice mismatch. The structure is fabricated using conventional photolithography and transfer techniques.
This effectively improves the absorption rate, response speed, and detection efficiency of photodetectors, reduces fabrication costs and process difficulty, solves the lattice mismatch problem, and enhances device performance.
Smart Images
Figure CN121843260B_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of photodetector technology, specifically relating to a gallium nitride / molybdenum disulfide heterojunction photodetector and its fabrication method. Background Technology
[0002] Traditional ultraviolet photodetectors are mainly based on wide-bandgap semiconductor materials, which require high-cost epitaxial growth and have complex and expensive fabrication processes. Two-dimensional materials have excellent photoelectric properties, but they suffer from low absorption and slow response in ultraviolet light detection, which limits their application in photodetectors.
[0003] In theory, combining three-dimensional and two-dimensional materials to form heterojunctions can effectively improve device performance. However, the lattice mismatch between three-dimensional and two-dimensional materials leads to an increase in interface defects, which affects device performance. Summary of the Invention
[0004] The purpose of this application is to provide a gallium nitride / molybdenum disulfide heterojunction photodetector and its fabrication method, which can effectively avoid lattice mismatch problems while heterointegrating three-dimensional and two-dimensional materials, significantly improve device performance, and eliminate the need for epitaxial growth technology, thus reducing costs.
[0005] To achieve the above objectives, the first aspect of this application provides a gallium nitride / molybdenum disulfide heterojunction photodetector, comprising:
[0006] The gallium nitride layer has a first conductivity type;
[0007] A passivation layer covers the surface of the gallium nitride layer, the passivation layer having an opening area that exposes the gallium nitride layer;
[0008] A molybdenum disulfide thin film is transferred to the surface of the passivation layer, and at least a portion of the molybdenum disulfide thin film directly contacts the gallium nitride layer through the opening region to form a heterojunction;
[0009] The first electrode and the second electrode are electrically connected to the gallium nitride layer and the molybdenum disulfide thin film, respectively.
[0010] In one or more embodiments, at least a portion of the molybdenum disulfide film is in direct contact with the passivation layer to support the molybdenum disulfide film.
[0011] In one or more embodiments, the molybdenum disulfide film includes a first portion located in the opening region and a second portion surrounding the first portion and in direct contact with the passivation layer.
[0012] In one or more embodiments, the second electrode includes an annular portion and a main body portion connected to the annular portion, the annular portion surrounding the opening area and in direct contact with the molybdenum disulfide film.
[0013] In one or more embodiments, the passivation layer is a silicon dioxide layer or an aluminum oxide layer.
[0014] In one or more embodiments, the thickness of the passivation layer is 10~30 nm.
[0015] In one or more embodiments, the first conductivity type is n-type.
[0016] To achieve the above objectives, a second aspect of this application provides a method for fabricating a gallium nitride / molybdenum disulfide heterojunction photodetector as described in any of the above embodiments, comprising:
[0017] A substrate is provided, wherein the surface of the substrate is grown with the gallium nitride layer having a first conductivity type;
[0018] The passivation layer is deposited on the surface of the gallium nitride layer;
[0019] A hole is made in the passivation layer using photolithography to form the hole area;
[0020] A molybdenum disulfide film is transferred to the opening region using a wet transfer process, so that at least a portion of the molybdenum disulfide film is in direct contact with the gallium nitride layer.
[0021] Prepare the first electrode and the second electrode.
[0022] In one or more embodiments, in the step of depositing the passivation layer on the surface of the gallium nitride layer, the deposition is specifically atomic layer deposition, chemical vapor deposition, or physical vapor deposition.
[0023] In one or more embodiments, the step of creating a hole in the passivation layer using photolithography includes:
[0024] Photoresist is applied to the passivation layer;
[0025] The aperture region is defined on the photoresist by using a mask;
[0026] Using the photoresist as a mask, the passivation layer is etched to create the opening region by creating a hole in the passivation layer.
[0027] In one or more embodiments, the step of preparing the first electrode and the second electrode includes:
[0028] Photoresist is coated on the molybdenum disulfide thin film and the gallium nitride layer;
[0029] The regions of the first electrode and the second electrode are defined on the photoresist by using a mask;
[0030] Using the photoresist as a mask, metal is deposited by evaporation, and then the photoresist is stripped off to prepare the first electrode and the second electrode.
[0031] The advantages of this application, which differ from existing technologies, are:
[0032] This application forms a heterojunction by combining two-dimensional and three-dimensional materials, which can effectively improve device performance. At the same time, the molybdenum disulfide film is directly transferred to the surface of the passivation layer and directly contacts the gallium nitride layer through the opening region. There is no chemical bond between the molybdenum disulfide film and the gallium nitride layer, but they are bonded by van der Waals forces. Therefore, the lattice mismatch problem between the molybdenum disulfide film and the gallium nitride layer can be effectively solved, which helps to improve device performance.
[0033] In this application, a passivation layer is first deposited on the surface of the gallium nitride layer during fabrication, and then an opening region is formed by etching on the surface of the passivation layer. The surface of the gallium nitride layer exposed by the opening region is also effectively passivated, which can effectively reduce interface defects and further solve the lattice mismatch problem between the molybdenum disulfide film and the gallium nitride layer, thereby improving device performance.
[0034] The molybdenum disulfide thin film of this application includes a first portion located in the open area and a second portion located on the passivation layer. The passivation layer can provide a flat and smooth mechanical support for the molybdenum disulfide thin film. At the same time, when the molybdenum disulfide thin film covers the passivation layer, the passivation layer can absorb and release most of the stress through its own small deformation, reduce the stress on the MoS2 / GaN interface region, and thus help to further reduce the interface defect density.
[0035] The fabrication method of this application only requires conventional photolithography and transfer techniques, without the need for high-cost processes such as epitaxial growth. It avoids the use of expensive epitaxial growth equipment, adopts low-cost materials and processes, reduces the fabrication difficulty, improves process compatibility, and enables cost-effective and efficient device fabrication. Attached Figure Description
[0036] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0037] Figure 1This is a cross-sectional structural schematic diagram of one embodiment of the gallium nitride / molybdenum disulfide heterojunction photodetector of this application;
[0038] Figure 2 This is a top view schematic diagram of another embodiment of the gallium nitride / molybdenum disulfide heterojunction photodetector of this application;
[0039] Figure 3 This is a schematic flowchart illustrating one embodiment of the method for fabricating the gallium nitride / molybdenum disulfide heterojunction photodetector of this application.
[0040] Explanation of key figure labels:
[0041] Gallium nitride layer 100;
[0042] Passivation layer 200; Opening area 201;
[0043] Molybdenum disulfide film 300; Part 1 301; Part 2 302;
[0044] First electrode 400;
[0045] Second electrode 500; annular portion 501; main body portion 502. Detailed Implementation
[0046] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.
[0047] Existing ultraviolet photodetectors require high-cost epitaxial growth for fabrication, resulting in high production costs. Theoretically, combining three-dimensional and two-dimensional materials to form a heterojunction can effectively improve device performance. However, the lattice mismatch between the three-dimensional and two-dimensional materials leads to an increase in interface defects, which affects device performance.
[0048] To address the aforementioned issues, the applicant has developed a novel photodetector that significantly enhances device performance by combining three-dimensional and two-dimensional materials to form a heterojunction. This also effectively avoids lattice mismatch issues between different materials and offers advantages such as low manufacturing cost and simple fabrication process.
[0049] Specifically, please refer to Figure 1 , Figure 1 This is a cross-sectional structural schematic diagram of one embodiment of the gallium nitride / molybdenum disulfide heterojunction photodetector of this application.
[0050] like Figure 1 As shown, the photodetector includes a gallium nitride layer 100 and a passivation layer 200 stacked together, wherein the gallium nitride layer 100 has a first conductivity type, and an opening region 201 is formed on the passivation layer 200.
[0051] In one embodiment, the first conductivity type may be n-type; in other embodiments, the first conductivity type may be p-type.
[0052] The photodetector also includes a molybdenum disulfide film 300 transferred to the surface of the passivation layer 200, at least a portion of which directly contacts the gallium nitride layer 100 through an opening region 201 to form a heterojunction.
[0053] The photodetector also includes a first electrode 400 and a second electrode 500, which are electrically connected to the gallium nitride layer 100 and the molybdenum disulfide thin film, respectively.
[0054] In one embodiment, the passivation layer 200 can be a silicon dioxide layer or an aluminum oxide layer, and its thickness can be 10~30nm.
[0055] In one embodiment, the molybdenum disulfide film 300 can be a single-layer film, while in other embodiments it can be a multi-layer film, both of which can achieve the effects of this embodiment.
[0056] In one implementation, the photodetector may specifically be an ultraviolet photodetector.
[0057] Based on the above scheme, the heterojunction formed by combining two-dimensional and three-dimensional materials can effectively improve device performance. At the same time, the molybdenum disulfide film 300 is directly transferred to the surface of the passivation layer 200 and directly contacts the gallium nitride layer 100 through the opening region 201. There is no chemical bond between the molybdenum disulfide film 300 and the gallium nitride layer 100, but they are bonded by van der Waals forces. Therefore, the lattice mismatch problem between the molybdenum disulfide film 300 and the gallium nitride layer 100 can be effectively solved, which helps to improve device performance.
[0058] In addition, during fabrication, a passivation layer 200 can be deposited on the surface of the gallium nitride layer 100 first, and then an opening region 201 can be etched on the surface of the passivation layer 200. The surface of the gallium nitride layer 100 exposed by the opening region 201 is also effectively passivated, which can effectively reduce interface defects and further solve the lattice mismatch problem between the molybdenum disulfide thin film 300 and the gallium nitride layer 100, thereby improving device performance.
[0059] Furthermore, in this embodiment, the molybdenum disulfide film 300 is entirely located within the opening region 201. In other embodiments, the molybdenum disulfide film 300 may also be partially located on the surface of the passivation layer 200.
[0060] Specifically, please refer to Figure 2 , Figure 2 This is a top view schematic diagram of another embodiment of the gallium nitride / molybdenum disulfide heterojunction photodetector of this application.
[0061] like Figure 2 As shown, in this embodiment, the molybdenum disulfide film 300 includes a first portion 301 located within the opening region 201 and a second portion 302 located on the passivation layer 200.
[0062] Based on this scheme, the passivation layer 200 can provide a flat and smooth mechanical support for the molybdenum disulfide film 300. At the same time, when the molybdenum disulfide film 300 covers the passivation layer 200, the passivation layer 200 can absorb and release most of the stress through its own small deformation, reduce the stress on the MoS2 / GaN interface region, and thus help to further reduce the interface defect density.
[0063] Specifically, in this embodiment, the second part 302 surrounds the first part 301 to help disperse stress, while maximizing the contact area between the molybdenum disulfide film 300 and the underlying gallium nitride layer 100, increasing van der Waals adsorption force, and making the entire film more stably fixed.
[0064] Of course, in other embodiments, the second part 302 may also be located on one side of the first part 301, or the second part 302 may be located only on the periphery of a part of the first part 301, etc., all of which can achieve the effect of this embodiment to a certain extent.
[0065] Furthermore, such as Figure 2 As shown, in this embodiment, the second electrode 500 includes an annular portion 501 and a main body portion 502 connected to the annular portion 501. The annular portion 501 surrounds the opening area 201 and is in direct contact with the second portion 302.
[0066] Based on this scheme, omnidirectional uniform current collection can be achieved, reducing contact resistance and local losses, while significantly shortening the carrier transport path and improving response speed.
[0067] Of course, in other embodiments, the shapes of the first electrode 400 and / or the second electrode 500 can also be designed in other ways, as long as the first electrode 400 is electrically connected to the gallium nitride layer 100 and the second electrode 500 is electrically connected to the molybdenum disulfide thin film 300.
[0068] The photodetectors based on the above embodiments form heterojunctions by combining two-dimensional and three-dimensional materials, which effectively solves the lattice mismatch problem and reduces interface defects. This can significantly improve the absorption rate, response speed and detection efficiency of the photodetectors, thereby improving device performance.
[0069] This application also provides a method for fabricating a photodetector according to any of the above embodiments. Please refer to [link to relevant documentation]. Figure 3 , Figure 3 This is a schematic flowchart illustrating one embodiment of the method for fabricating the gallium nitride / molybdenum disulfide heterojunction photodetector of this application.
[0070] like Figure 3 As shown, the preparation method includes:
[0071] S101. A substrate is provided, and a gallium nitride layer having a first conductivity type is grown on the surface of the substrate.
[0072] In one embodiment, the substrate may specifically be a sapphire substrate.
[0073] S102, A passivation layer is deposited on the surface of the gallium nitride layer.
[0074] The deposition can be specifically atomic layer deposition, chemical vapor deposition, or physical vapor deposition, all of which can achieve the effect of this embodiment.
[0075] S103. Using photolithography, holes are made in the passivation layer to form the hole area.
[0076] Specifically, this embodiment utilizes photolithography to create holes in the passivation layer. The hole-creating steps can be specifically as follows:
[0077] Photoresist is applied onto the passivation layer;
[0078] The aperture area is defined on the photoresist using a mask;
[0079] Using photoresist as a mask, a passivation layer is etched to create an opening region by creating a hole in the passivation layer.
[0080] S104. Molybdenum disulfide film is transferred to the opening area by a wet transfer process.
[0081] In this embodiment, a molybdenum disulfide film is transferred to the open area of the passivation layer using a wet transfer process, so that at least a portion of the molybdenum oxide film is in direct contact with the gallium nitride layer.
[0082] The molybdenum disulfide film can be prepared by mechanical exfoliation or by chemical vapor deposition, both of which can be applied to the wet transfer process of this embodiment.
[0083] S105, Prepare the first electrode and the second electrode.
[0084] Specifically, the steps for preparing the first electrode and the second electrode can be as follows:
[0085] Photoresist is coated onto a molybdenum disulfide thin film and a gallium nitride layer;
[0086] The regions of the first and second electrodes are defined on the photoresist using a mask;
[0087] Using photoresist as a mask, metal is deposited by evaporation, and then the photoresist is stripped off to prepare the first electrode and the second electrode.
[0088] Based on the methods described above, only conventional photolithography and transfer techniques are required, eliminating the need for high-cost processes such as epitaxial growth. This avoids the use of expensive epitaxial growth equipment, adopts low-cost materials and processes, reduces fabrication difficulty, improves process compatibility, and enables cost-effective device fabrication.
[0089] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.
[0090] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A gallium nitride / molybdenum disulfide heterojunction photodetector, characterized in that, include: The gallium nitride layer has a first conductivity type; A passivation layer covers the surface of the gallium nitride layer, the passivation layer having an opening area that exposes the gallium nitride layer; A molybdenum disulfide thin film is transferred to the surface of the passivation layer, and at least a portion of the molybdenum disulfide thin film directly contacts the gallium nitride layer through the opening region to form a heterojunction; The first electrode and the second electrode are electrically connected to the gallium nitride layer and the molybdenum disulfide thin film, respectively. The molybdenum disulfide film includes a first portion located in the opening region and a second portion surrounding the first portion and in direct contact with the passivation layer.
2. The gallium nitride / molybdenum disulfide heterojunction photodetector according to claim 1, characterized in that, At least a portion of the molybdenum disulfide film is in direct contact with the passivation layer to support the molybdenum disulfide film.
3. The gallium nitride / molybdenum disulfide heterojunction photodetector according to claim 1, characterized in that, The second electrode includes an annular portion and a main body portion connected to the annular portion. The annular portion surrounds the opening area and is in direct contact with the molybdenum disulfide film.
4. The gallium nitride / molybdenum disulfide heterojunction photodetector according to claim 1, characterized in that, The passivation layer is a silicon dioxide layer or an aluminum oxide layer, and the thickness of the passivation layer is 10~30nm.
5. The gallium nitride / molybdenum disulfide heterojunction photodetector according to claim 1, characterized in that, The first conductivity type is n-type.
6. A method for fabricating a gallium nitride / molybdenum disulfide heterojunction photodetector as described in any one of claims 1 to 5, characterized in that, include: A substrate is provided, wherein the surface of the substrate is grown with the gallium nitride layer having a first conductivity type; The passivation layer is deposited on the surface of the gallium nitride layer; A hole is made in the passivation layer using photolithography to form the hole area; A molybdenum disulfide film is transferred to the opening region using a wet transfer process, so that at least a portion of the molybdenum disulfide film is in direct contact with the gallium nitride layer. Prepare the first electrode and the second electrode.
7. The preparation method according to claim 6, characterized in that, In the step of depositing the passivation layer on the surface of the gallium nitride layer, the deposition is specifically atomic layer deposition, chemical vapor deposition, or physical vapor deposition.
8. The preparation method according to claim 6, characterized in that, The step of creating a hole in the passivation layer using photolithography includes: Photoresist is applied to the passivation layer; The aperture region is defined on the photoresist by using a mask; Using the photoresist as a mask, the passivation layer is etched to create the opening region by creating a hole in the passivation layer.
9. The preparation method according to claim 6, characterized in that, The steps for preparing the first electrode and the second electrode include: Photoresist is coated on the molybdenum disulfide thin film and the gallium nitride layer; The regions of the first electrode and the second electrode are defined on the photoresist by using a mask; Using the photoresist as a mask, metal is deposited by evaporation, and then the photoresist is stripped off to prepare the first electrode and the second electrode.