Self-driven photoelectric detector and preparation method thereof

Abstract

The invention relates to a self-driven photoelectric detector and a preparation method thereof, the self-driven photoelectric detector comprises a silicon substrate sheet, the silicon substrate sheet comprises bottom silicon, a silicon dioxide layer and a graphene layer, the graphene layer covers the surface of the silicon dioxide layer and is used for collecting photon-generated carriers transmitted from a light absorption layer and exporting current, and the tunneling layer is made of hexagonal boron nitride. The tunneling layer covers the surfaces of the graphene layer and the silicon dioxide layer, the light absorption layer is made of molybdenum disulfide, located on the surface of the tunneling layer and used for absorbing light and generating photon-generated carriers, and the metal electrodes are arranged on the surfaces of the graphene layer and the light absorption layer respectively and used for being connected with an external circuit. By constructing a graphene / hexagonal boron nitride / molybdenum disulfide heterojunction unique structure, the characteristics of hexagonal boron nitride with an NBVN antisite nitrogen vacancy defect are fully exerted, so that the detector can automatically generate current inside only through illumination in a state without external bias voltage, and the photoelectric detection without the external bias voltage is realized; and rapid and stable detection is realized due to the characteristic of high sensitivity of the material.

Description

Technical Field

[0001] The invention relates to the field of photoelectric detection equipment, in particular to a self-driven photoelectric detector. Background Art

[0002] Since the separation of graphene in 2004, a new era of two-dimensional material research has been launched. The application exploration of these materials in the fields of electronics and optoelectronics has made great progress. They play an important role in transistors, photodetectors, optical modulators, supercapacitors and solar cells. Through the clever selection of different two-dimensional materials and precise stacking technology, we are able to maximize the unique properties of each material. Photodetectors based on two-dimensional materials show many advantages, such as extremely high response rate, excellent detection efficiency, wide bandwidth compatibility and extremely short response delay.

[0003] However, these detectors often require external bias to work, a limitation that makes them difficult to popularize in environments where wiring is impossible or continuous power supply is difficult. At the same time, due to the interference of dark current, the switching ratio of these photodetectors is usually not ideal, and the response time is mostly in the millisecond level, which has certain limitations in the application of optical switches.

[0004] Publication No. CNCN201811181613.4 provides a three-in-one composite self-driven photodetector and a preparation method thereof, which uses a perovskite solar cell, a thermoelectric power generation sheet, and a pressure power generation sheet in parallel as the voltage drive of the perovskite photodetector. The perovskite solar cell, the thermoelectric power generation sheet, and the pressure power generation sheet can individually provide voltage for the perovskite photodetector. At the same time, the thermoelectric power generation sheet converts thermal energy into electrical energy, and the pressure power generation sheet converts external kinetic energy into electrical energy.

[0005] Although the above-mentioned prior art can realize photoelectric detection without external electric energy, a power system is still required to power the detection system, and the detection device itself still requires an external bias voltage. Summary of the invention

[0006] The object of the present invention is to provide a self-driven photodetector to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A self-driven photodetector, comprising:

[0009] A silicon substrate, wherein the silicon substrate comprises a bottom silicon layer and a silicon dioxide layer stacked in sequence from bottom to top, wherein the bottom silicon layer is used to provide mechanical support, and the silicon dioxide layer is used for electrical isolation;

[0010] A graphene layer, which covers the surface of the silicon dioxide layer and is used to collect photogenerated carriers transmitted from the light absorption layer and derive current;

[0011] A tunneling layer, the tunneling layer covers the surface of the graphene layer and the silicon dioxide layer, and is used to electrically isolate the graphene layer from the light absorbing layer to avoid direct contact between the graphene layer and the light absorbing layer, and the material of the tunneling layer is hexagonal boron nitride;

[0012] A light absorption layer, which is located on the surface of the tunneling layer and is used to absorb light and generate photogenerated carriers. The carriers are transmitted to the graphene layer through the tunneling layer. The material of the light absorption layer is molybdenum disulfide;

[0013] The metal electrodes are provided in two groups and are respectively provided on the surface of the graphene layer and the light absorption layer, one group is in ohmic contact with the graphene layer and is set as a drain electrode, and the other group is in ohmic contact with the light absorption layer and is set as a source electrode, and is used to connect to an external circuit to lead out the photogenerated carriers generated by the light absorption layer.

[0014] Preferably, the tunnel layer molybdenum disulfide material has a NBVN anti-site nitrogen vacancy defect.

[0015] Preferably, the light absorbing layer is biased on the upper surface of one side of the tunneling layer, and the graphene layer is biased on the lower surface of the other side of the tunneling layer. The graphene layer, the tunneling layer and the light absorbing layer constitute a graphene / hexagonal boron nitride / molybdenum disulfide heterojunction with the tunneling layer as a barrier.

[0016] Preferably, the thickness of the silicon dioxide layer on the silicon substrate is in the range of 200nm-300nm, the thickness of the graphene layer is in the range of 0.34nm-0.77nm, the thickness of the tunneling layer is in the range of 10nm-20nm, the thickness of the light absorption layer is in the range of 0.65nm-0.88nm, and the metal electrode material is a chromium-gold alloy.

[0017] The present invention further provides a method for preparing a self-driven photoelectric detector, which is used to prepare the above-mentioned self-driven photoelectric detector, and the specific steps include:

[0018] S1. A graphene layer is obtained by mechanical stripping. The graphene is attached to the surface of the silicon dioxide layer of the silicon substrate. The tunneling layer hexagonal boron nitride and the light absorption layer molybdenum disulfide are prepared by mechanical stripping through a polymer sacrificial substrate.

[0019] S2. Aligning the tunneling layer hexagonal boron nitride with the graphene layer and laminating them, and aligning the light absorption layer molybdenum disulfide with the tunneling layer hexagonal boron nitride and laminating them, thereby forming a three-layer heterostructure;

[0020] S3, coating a photoresist film with uniform thickness on the three-layer heterojunction using a coating machine;

[0021] S4, drawing the electrode pattern by electron beam exposure and developing and fixing;

[0022] S5. Use vacuum evaporation method to build chromium-gold alloy of metal electrode and clean it.

[0023] Preferably, the silicon substrate having a silicon dioxide layer with a thickness of 200nm-300nm obtained by dry oxygen oxidation is prepared, and the polymer sacrificial substrate is polydimethylsiloxane.

[0024] Preferably, in a glove box with an inert gas atmosphere, the tunneling layer hexagonal boron nitride is laminated to the graphene layer, and the absorption layer molybdenum disulfide is laminated to the tunneling layer hexagonal boron nitride, and both are heated to 55°C for 10 minutes to achieve a completely laminated three-layer heterostructure. After the three-layer heterostructure is stacked, it is annealed in an inert atmosphere, and the annealing temperature is 150°C, the heating rate is 5°C / min, and the time is 120min.

[0025] Preferably, the photoresist used is polymethyl methacrylate, and the spin coater used is set to a low speed of 500 r / min for 5 seconds and a high speed of 4000 r / min for 60 seconds, and the glue is baked at 150°C for 5 minutes. In the development stage, the developer is a 1:3 mixture of deionized water and isopropyl alcohol, and the development time is 25 seconds. At the end of development, the silicon wafer is quickly placed in a fixing solution, and the fixing solution used is an isopropyl alcohol solution, and the fixing time is 30 seconds.

[0026] Preferably, 5 nm of chromium and 50 nm of gold are plated by electron beam evaporation at a rate of 5 A / s, and then the device is cleaned.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention constructs a unique structure of graphene / hexagonal boron nitride / molybdenum disulfide heterojunction, giving full play to the characteristics of hexagonal boron nitride with NBVN anti-site nitrogen vacancy defects, so that the detector can generate current in itself by light alone without external bias, thereby realizing photoelectric detection without external bias, and the high sensitivity of the material itself realizes fast and stable detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic cross-sectional view of the structure of the present invention;

[0030] Figure 2 It is the response time curve diagram of the present invention;

[0031] Figure 3 It is the self-driving curve diagram of the present invention;

[0032] Figure 4 This is a graph showing the response of the present invention to light of different wavelengths;

[0033] In the figure: 10 silicon substrate, 11 bottom silicon, 12 silicon dioxide layer, 20 conductive layer, 30 tunneling layer, 40 light absorption layer, 50 metal electrode. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Example:

[0036] See also Figures 1 to 4 , the present invention provides a technical solution:

[0037] A self-driven photodetector, comprising:

[0038] A silicon substrate 10, the silicon substrate comprises a bottom silicon 11 and a silicon dioxide layer 12 stacked in sequence from bottom to top, the bottom silicon 11 is used to provide mechanical support to ensure the stability and durability of the entire photodetector structure, and the silicon dioxide layer 12 is used for electrical isolation to prevent current leakage between the bottom silicon 11 and other conductive layers, thereby improving the working efficiency and reliability of the device;

[0039] The graphene layer 20 covers the surface of the silicon dioxide layer 12 and is used to collect the photogenerated carriers transmitted from the light absorption layer 40 and derive the current. Due to its excellent conductivity and ultra-high carrier mobility, graphene can quickly and efficiently conduct electrons and holes, thereby improving the response speed and sensitivity of the photodetector. In addition, the two-dimensional structure and high light transmittance of graphene enable it to effectively collect the photogenerated carriers generated by the light absorption layer 40 without significantly absorbing light. ;

[0040] The tunneling layer 30 covers the surface of the graphene layer 20 and the silicon dioxide layer 12, and is used to electrically isolate the graphene layer 20 and the light absorbing layer 40 to avoid direct contact between the graphene layer 20 and the light absorbing layer 40. The material of the tunneling layer 30 is hexagonal boron nitride, which has excellent electrical insulation performance and thermal stability. At the same time, its lattice structure matches that of graphene and molybdenum disulfide, which helps to form a high-quality interface;

[0041] The light absorption layer 40 is located on the surface of the tunneling layer 30, and is used to absorb light and generate photogenerated carriers. The material of the light absorption layer 40 is molybdenum disulfide. Molybdenum disulfide, as a two-dimensional semiconductor material, has a direct band gap structure and can efficiently absorb visible light and near-infrared light. The photogenerated carriers (electron-hole pairs) generated by the light absorption layer 40 are transmitted to the graphene layer 20 through the tunneling layer 30, thereby forming a photocurrent, thereby improving the photoelectric conversion efficiency of the detector;

[0042] The metal electrode 50 includes two groups of metal electrodes 50, which are respectively arranged on the surface of the graphene layer 20 and the light absorption layer 40. One group is in ohmic contact with the graphene layer 20 and is set as a drain, and the other group is in ohmic contact with the light absorption layer 40 and is set as a source. The metal electrodes 50 are used to connect to an external circuit and conduct the photogenerated carriers generated by the light absorption layer 40 to achieve effective output and transmission of photoelectric signals.

[0043] As a preferred embodiment, the tunneling layer 30 molybdenum disulfide material has a NBVN anti-site nitrogen vacancy defect, which forms a unique mechanism in the molybdenum disulfide material: the nitrogen atom mistakenly occupies the lattice position originally belonging to the boron atom, and the original position of the nitrogen atom becomes vacant. This atomic-scale structural rearrangement leads to a significant distortion of the local hexagonal boron nitride crystal lattice. This structural distortion introduces new electronic states into the band structure of hexagonal boron nitride, namely the so-called defect ground state and defect excited state.

[0044] As a preferred embodiment, the light absorbing layer 40 is biased on the upper surface of one side of the tunneling layer 30, and the graphene layer 20 is biased on the lower surface of the other side of the tunneling layer 30. The graphene layer 20, the tunneling layer 30 and the light absorbing layer 40 constitute a graphene / hexagonal boron nitride / molybdenum disulfide heterojunction with the tunneling layer 30 as a barrier. At the contact interface between the graphene layer 20 and the hexagonal boron nitride of the tunneling layer 30, when the defect state in the hexagonal boron nitride of the tunneling layer 30 is excited by external energy, its band structure will undergo specific adjustments. This change causes the Fermi level of the graphene layer 20 to be located exactly in the energy gap between the defect excited state and the defect ground state of the hexagonal boron nitride of the tunneling layer 30. Therefore, the graphene layer 20 at this interface can not only It serves as a conductive channel and also as a temporary storage for electrons and holes to capture and temporarily store carriers from the hexagonal boron nitride layer of the tunneling layer 30. There is a complex and variable band alignment at the contact interface between the hexagonal boron nitride layer 30 and the molybdenum disulfide layer 40 of the light absorption layer, and the change of the band alignment depends on whether the defect state in the hexagonal boron nitride layer of the tunneling layer 30 is excited. When no defect state is excited, a type I band alignment is formed at the interface, that is, the conduction band minimum and valence band maximum of the molybdenum disulfide of the light absorption layer 40 are respectively located below and above the intrinsic energy band of the hexagonal boron nitride of the tunneling layer 30, forming a "misplaced" band structure, which limits the electrons and holes between the tunneling layer 30 and the light absorption layer 40. When the defect state in the hexagonal boron nitride of the tunneling layer 30 is effectively excited, the band alignment between the hexagonal boron nitride of the tunneling layer 30 and the molybdenum disulfide of the light absorbing layer 40 is transformed into type II, that is, the conduction band minimum and the valence band maximum of the molybdenum disulfide of the light absorbing layer 40 are both located below the defect excited state and the defect ground state of the hexagonal boron nitride of the tunneling layer 30, forming a "staggered" band structure. This structure promotes the effective separation and transfer of photoexcited carriers between the tunneling layer 30 and the light absorbing layer 40, because electrons and holes can be more easily transmitted through the interface, and the defect ground state in the hexagonal boron nitride of the tunneling layer 30 has an assisting effect as an intermediate state, and the hexagonal boron nitride of the tunneling layer 30 assists the photoexcited holes from the disulfide Molybdenum sulfide is efficiently transferred to graphene, and the change in band alignment caused by the defective ground state plays an important role in achieving sensitive photoelectric response in the absence of an external bias. In the case of type I alignment, the hexagonal boron nitride layer of the tunneling layer 30 acts as a high potential barrier, preventing the flow of charges between the graphene layer 20 and the light absorption layer 40 molybdenum disulfide, which means that in this alignment, the photoelectric response of the device is severely limited. In the case of type II alignment, photoexcited holes can be more easily transmitted through the interface and captured by the graphene layer 20, at which time current is spontaneously and sensitively generated inside, achieving a sensitive photoelectric response, and the excitation of the defect state of the hexagonal boron nitride in the tunneling layer 30 can also be achieved by light.

[0045] As a preferred embodiment, the thickness of the silicon dioxide layer 12 on the silicon substrate 10 is in the range of 200nm-300nm, the thickness of the graphene layer 20 is in the range of 0.34nm-0.77nm, the thickness of the tunneling layer 30 is in the range of 10nm-20nm, the thickness of the light absorption layer 40 is in the range of 0.65nm-0.88nm, and the material of the metal electrode 50 is a chromium-gold alloy, chromium is used to improve the adhesion of the metal to the graphene or molybdenum disulfide, and gold provides good conductivity.

[0046] As a preferred embodiment, Figure 2 As shown, when the light is turned on, the defect states in the hexagonal boron nitride realize unidirectional charge flow. This special charge transfer mechanism promotes the efficient separation of electron-hole pairs in molybdenum disulfide, thereby improving the efficiency of photocurrent generation and ensuring a fast photogenerated carrier transport interface with a rising edge of 7μs and a falling edge of 7μs, which has excellent switching device potential.

[0047] As a preferred embodiment, Figure 3 As shown, under the excitation of light with a wavelength of 405nm, it can be observed that the device exhibits significant self-driven behavior. This self-driven behavior is manifested in that the device can still generate and maintain a certain photocurrent without external electrode power supply. The occurrence of this phenomenon is attributed to the photogenerated carriers generated by the graphene / hexagonal boron nitride / molybdenum disulfide heterojunction under 405nm wavelength light. These carriers are separated under the action of the internal electric field and move to the source and drain respectively, thereby forming a photocurrent. The emergence of self-driven behavior not only reduces the energy consumption of the device, but also improves its practicality in fields such as photoelectric detection.

[0048] As a preferred embodiment, Figure 4 The ultrafast response speed self-driven photodetector provided in the embodiment has a light response diagram of different wavelengths. Due to the different responsiveness of hexagonal boron nitride and TMD to light wavelength, we can design a two-dimensional heterojunction photoelectric device with different photoelectric response characteristics to different wavelengths from the heterostructure. It can be seen that the switching ratio can reach up to 105 under 405nm irradiation. The excellent switching ratio represents the high sensitivity of the device.

[0049] The present invention further provides a method for preparing a self-driven photoelectric detector, which is used to prepare the self-driven photoelectric detector, and the specific steps include:

[0050] S1, using a mechanical stripping method to obtain a conductive layer 20 of graphene bonded to the silicon dioxide surface of the silicon substrate 10, and also using a mechanical stripping method to prepare a tunneling layer 30 of hexagonal boron nitride and a light absorption layer 40 of molybdenum disulfide through a polymer sacrificial substrate;

[0051] S2. Align the hexagonal boron nitride of the tunneling layer 30 with the graphene of the conductive layer 20 and laminate them, and align the molybdenum disulfide of the light absorbing layer 40 with the hexagonal boron nitride of the tunneling layer 30 and laminate them, so as to form a three-layer heterostructure;

[0052] S3, coating a photoresist film with uniform thickness on the three-layer heterojunction using a coating machine;

[0053] S4, drawing an electrode pattern by electron beam exposure and then developing and fixing;

[0054] S5. Use vacuum evaporation method to build metal electrode 50 chrome-gold alloy and clean it.

[0055] As a preferred embodiment, a silicon substrate 10 with a silicon dioxide thickness of 200nm-300nm is obtained by dry oxygen oxidation, and the polymer sacrificial substrate is polydimethylsiloxane. A small amount of block-shaped layered graphene material is placed on a tape with a specific strong viscosity. The transparent tape is repeatedly pasted and separated, and the state of the graphene material on the tape is observed. After determining that the graphene material is successfully dissociated, a tape with a weaker viscosity is used to peel off a thin graphene crystal from the tape with a strong viscosity, and then silicon / silicon dioxide is used to fit it. The tape is torn off after pressing for 10 seconds, and there is a chance to obtain high-quality few-layer or single-layer graphene two-dimensional materials. Then, the above method is used to prepare a tape with a weaker viscosity containing hexagonal boron nitride and molybdenum disulfide crystals, and a polymer sacrificial substrate polydimethylsiloxane carried by a glass slide is used to fit it. The tape is torn off after pressing for 10 seconds, and there is a chance to obtain high-quality few-layer or single-layer hexagonal boron nitride and molybdenum disulfide two-dimensional materials.

[0056] As a preferred embodiment, in a glove box filled with argon, a vacuum adsorption mechanical pump is used to fix the silicon wafer substrate on the three-axis translation stage 1, the target sample is found and placed in the center through an optical microscope, and then the three-axis translation stage 2 is used to fix the glass slide with polydimethylsiloxane. Without changing the optical path, the x-axis and y-axis of the three-axis translation stage 2 are used to move the glass slide until the target two-dimensional thin layer of hexagonal boron nitride material is in the center of the field of view, and the z-axis knob of the three-axis translation stage is used to press down the glass slide carrying the two-dimensional thin layer of hexagonal boron nitride material, and at the same time, the x-axis and y-axis are fine-tuned to make the two samples in the target position until the polydimethylsiloxane is fixed. Dimethylsiloxane is bonded to a silicon wafer substrate, heated to 60°C and waited for 10 minutes before lifting the glass slide. By reducing the van der Waals force between polydimethylsiloxane and the material, the two-dimensional thin layer of hexagonal boron nitride material is promoted to fall off the polydimethylsiloxane. Similarly, a three-layer heterostructure is obtained after transferring a single layer of molybdenum disulfide. After the three-layer heterostructure is stacked, annealing is required immediately. A tubular furnace is used to anneal the heterostructure, wherein the annealing temperature is 150°C, the heating rate of the annealing is 5°C / min, the annealing time is 120min, and the annealing atmosphere is an argon atmosphere.

[0057] As a preferred embodiment, the photoresist used is polymethyl methacrylate. A silicon wafer sample is placed on a coating machine, and photoresist is dripped on the surface of the silicon wafer for coating. The low speed is 500r / min, the duration is 5 seconds, and the high speed is 4000r / min, the duration is set to 60 seconds, and a uniform thin film can be plated. The film sample is placed on a heating table for baking at a temperature of 150°C for 5 minutes, which can evaporate the residual solvent in the photoresist and solidify the polymethyl methacrylate.

[0058] As a preferred embodiment, the software supporting the electron beam exposure system is used to design the electrode pattern to be exposed, and the exposure parameters are set as exposure dose: 160μC / cm, beam current: 0.88nA, and the overall exposure area is a square area of ​​1000μm×1000μm. In the exposed area, the polymethyl methacrylate macromolecular structure is destroyed and can be dissolved in the developer, so as to achieve the effect of forming the required metal electrode channel. The developer used is a 1:3 mixture of deionized water and isopropyl alcohol, and the development time is 25 seconds. At the moment when the development is completed, the silicon wafer is quickly placed in a fixing solution, and the fixing solution used is an isopropyl alcohol solution, and the fixing time is 30 seconds.

[0059] As a preferred embodiment, a silicon wafer sample is placed in an electron beam evaporation platform to deposit chromium metal and gold metal in sequence at a rate of 5 A / s, obtaining a 5 nm chromium metal layer and a 50 nm gold metal layer on the sample surface, and the device is placed in an acetone solution and immersed for a period of time to dissolve the photoresist, and then a disposable plastic dropper is used to remove the photoresist of the unphotolithographic portion and the metal layer thereon and leave the designed metal electrode, and then an isopropanol solution is used to remove the acetone liquid remaining on the surface, and finally the device is blown dry with a high-pressure nitrogen air gun.

[0060] The working principle of the present invention is as follows: when light irradiates the light absorbing layer 40, the energy of the light absorbing layer 40 is absorbed by the light absorbing layer 40. When the energy of the photon is greater than or equal to the band gap energy of the molybdenum disulfide, the electrons are excited to transition from the valence band to the conduction band. In the transition process, free electrons and holes are generated to form carriers. These carriers become the source of the photocurrent. At the interface between the tunneling layer 30, hexagonal boron nitride, and the light absorbing layer 40, due to the different energy band structures of the two materials, the conventional defect state of the hexagonal boron nitride is not enough to cause these carriers to undergo a sufficient quantum tunneling effect to form a current, but This is because after the hexagonal boron nitride in the tunneling layer 30 absorbs light energy, the defect state is excited and transformed into a defect excited state, and the energy band alignment between the hexagonal boron nitride in the tunneling layer 30 and the molybdenum disulfide in the light absorption layer 40 is transformed into type II, which promotes the effective separation and transfer of light-excited carriers between the two layers. The separated electrons and holes move in different directions respectively. The electrons are transferred to the graphene layer, and the holes are transferred to the source. In this process, in the absence of an external bias, the separation and flow of electrons and holes form a closed current path, thereby generating a photocurrent, thereby realizing self-driven photoelectric detection.

[0061] 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 self-driven photodetector, characterized in that: include: A silicon substrate (10), the silicon substrate comprising a bottom silicon layer (11) and a silicon dioxide layer (12) stacked in sequence from bottom to top, the bottom silicon layer (11) being used to provide mechanical support, and the silicon dioxide layer (12) being used for electrical isolation; A graphene layer (20), the graphene layer (20) covering the surface of the silicon dioxide layer (12) and used for collecting photogenerated carriers transmitted from the light absorption layer (40) and deriving current; A tunneling layer (30), the tunneling layer (30) covers the surface of the graphene layer (20) and the silicon dioxide layer (12), and is used to electrically isolate the graphene layer (20) and the light absorption layer (40) to avoid direct contact between the graphene layer (20) and the light absorption layer (40), and the material of the tunneling layer (30) is hexagonal boron nitride; A light absorbing layer (40), the light absorbing layer (40) being located on the surface of the tunneling layer (30) and used for absorbing light and generating photogenerated carriers, the carriers being transmitted to the graphene layer (20) through the tunneling layer (30), the material of the light absorbing layer (40) being molybdenum disulfide; The metal electrodes (50) are provided in two groups and are respectively provided on the surfaces of the graphene layer (20) and the light absorption layer (40), one group is in ohmic contact with the graphene layer (20) and is set as a drain electrode, and the other group is in ohmic contact with the light absorption layer (40) and is set as a source electrode, and is used to connect to an external circuit and conduct light-generated carriers generated by the light absorption layer (40).

2. A self-driven photodetector according to claim 1, characterized in that: The hexagonal boron nitride material of the tunneling layer (30) has a NBVN anti-site nitrogen vacancy defect.

3. The self-driven photodetector according to claim 1, characterized in that: The light absorbing layer (40) is biasedly arranged on the upper surface of one side of the tunneling layer (30), and the graphene layer (20) is biasedly arranged on the lower surface of the other side of the tunneling layer (30). The graphene layer (20), the tunneling layer (30) and the light absorbing layer (40) form a graphene / hexagonal boron nitride / molybdenum disulfide heterojunction with the tunneling layer (30) as a potential barrier.

4. The self-driven photodetector according to claim 1, characterized in that: The silicon dioxide layer (12) on the silicon substrate (10) has a thickness ranging from 200 nm to 300 nm, the graphene layer (20) has a thickness ranging from 0.34 nm to 0.77 nm, the tunneling layer (30) has a thickness ranging from 10 nm to 20 nm, the light absorption layer (40) has a thickness ranging from 0.65 nm to 0.88 nm, and the metal electrode (50) is made of a chromium-gold alloy.

5. A method for preparing a self-driven photoelectric detector, characterized in that: The method is used to prepare the self-driven photodetector according to any one of claims 1 to 4, and the specific steps include: S1, using a mechanical exfoliation method to obtain a graphene layer (20) wherein the graphene is bonded to the surface of a silicon dioxide layer (12) of a silicon substrate (10), and also using a mechanical exfoliation method to prepare a tunneling layer (30) of hexagonal boron nitride and a light absorption layer (40) of molybdenum disulfide through a polymer sacrificial substrate; S2. Aligning the tunneling layer (30) hexagonal boron nitride with the graphene layer (20) and laminating them by dry transfer, and aligning the light absorption layer (40) molybdenum disulfide with the tunneling layer (30) and laminating them, thereby forming a three-layer heterostructure; S3, coating a photoresist film with uniform thickness on the three-layer heterojunction using a coating machine; S4, drawing the electrode pattern by electron beam exposure and developing and fixing; S5. Use vacuum evaporation to form a metal electrode (50) of chromium-gold alloy and clean it.

6. The method for preparing a self-driven photodetector according to claim 5, characterized in that: The silicon substrate (10) having a silicon dioxide layer (12) with a thickness of 200nm-300nm is obtained by dry oxygen oxidation, and the polymer sacrificial substrate is polydimethylsiloxane.

7. The method for preparing a self-driven photodetector according to claim 5, characterized in that: In a glove box with an inert gas atmosphere, the tunneling layer (30) hexagonal boron nitride is laminated to the graphene layer (20), and the absorption layer (40) molybdenum disulfide is laminated to the tunneling layer (30) hexagonal boron nitride, and both are heated to 55° C. for 10 minutes to achieve a completely laminated three-layer heterostructure. After the three-layer heterostructure is stacked, it is annealed in an inert atmosphere, and the annealing temperature is 150° C., the heating rate is 5° C. / min, and the time is 120 min.

8. The method for preparing a self-driven photodetector according to claim 5, characterized in that: The photoresist used is polymethyl methacrylate, and the spin coater used is set to a low speed of 500r / min for 5 seconds and a high speed of 4000r / min for 60 seconds, and the glue is baked at 150°C for 5 minutes. In the development stage, the developer is a 1:3 mixture of deionized water and isopropyl alcohol. The development time is 25 seconds. At the end of development, the silicon wafer is quickly placed in the fixing solution. The fixing solution used is an isopropyl alcohol solution, and the fixing time is 30 seconds.

9. The method for preparing a self-driven photodetector according to claim 5, characterized in that: 5 nm of chromium and 50 nm of gold were deposited by electron beam evaporation at a rate of 5 A / s, and the device was then cleaned.

Images