Flexible photoelectric detector based on graphene-two-dimensional material Schottky heterojunction

Abstract

The invention relates to a flexible photoelectric detector based on a graphene-two-dimensional material Schottky heterojunction. The flexible photoelectric detector comprises a flexible substrate insulating layer, a two-dimensional thin film Schottky heterojunction, a metal interconnection wire and a top flexible packaging layer, a graphene layer, a two-dimensional material layer and a hexagonal boron nitride layer are sequentially arranged in the direction away from the flexible substrate insulating layer. A two-dimensional thin film Schottky heterojunction is formed in an overlapped region of the graphene layer, the two-dimensional material layer and the hexagonal boron nitride layer; the top flexible packaging layer covers the surface of the flexible substrate insulating layer, and the top flexible packaging layer at the tail end of the metal interconnection wire is etched. The graphene-based photoelectric detector has the beneficial effects that the sensitivity and the response speed of the photoelectric detector are remarkably improved by using the ballistic transport and ballistic avalanche effects of electrons through the Schottky heterojunction formed by the graphene and the two-dimensional material.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectric detectors, and more specifically, to a flexible photoelectric detector based on a graphene-two-dimensional material Schottky heterojunction. Background Art

[0002] A photodetector is a device that uses the photoelectric effect of matter to convert light signals into electrical signals. It is the core component of the optoelectronic system, and its role in the optoelectronic system is to detect and measure signals and extract certain necessary information for subsequent applications. As a new type of information transmission carrier, light has gradually replaced electronic communication systems due to its high speed, large capacity, low cost and security. It has developed into the main pillar of global information carrying facilities and has a wide range of application needs in various fields such as industry, agriculture, medicine, transportation, military and aerospace.

[0003] Avalanche photodetectors (APDs) are extremely sensitive photodetectors that convert light into current or voltage signals. Avalanche photodiodes typically operate at relatively high reverse bias voltages of tens or even hundreds of volts. In this case, photogenerated electron-hole pairs are accelerated by the electric field, so they can generate more carriers through impact ionization. The avalanche effect causes the number of original photogenerated carriers to multiply rapidly, forming a strong current signal; this current signal is much larger than the initial photogenerated current, achieving a significant amplification of the light signal. Therefore, avalanche photodetectors can detect very weak light signals and have the characteristics of high sensitivity. Traditional silicon-based avalanche photodetectors have excellent performance, but they cannot be made flexible, and their application areas are greatly limited, especially in the biomedical field, where wearable flexible electronic devices are showing positive application prospects; while other types of flexible photodetectors, on the one hand, have inferior detection performance to silicon-based photodetectors, and on the other hand, have high preparation costs and are not compatible with existing integrated circuit processes.

[0004] CN201511029416.7 is based on a two-dimensional layered material pin heterojunction optoelectronic device. The avalanche detector includes a bottom-to-top structure on a substrate: a substrate insulating layer, the insulating layer includes silicon dioxide, a PMMA flexible insulating substrate; a pin heterojunction, the pin heterojunction includes a p-type semiconductor two-dimensional thin film material, the p-type semiconductor two-dimensional thin film material is stacked under a boron nitride with a certain number of layers, and an n-type semiconductor two-dimensional thin film material film is stacked on the above-mentioned boron nitride, the entire heterojunction device layer is placed on the substrate insulating layer, and the boron nitride separates the two semiconductor two-dimensional thin film material layers; a top gate metal The electrode is made on the heterojunction covered by the top gate dielectric layer; the metal electrode layer includes a source electrode layer and a drain electrode layer, the source electrode layer and the drain electrode layer respectively cover the n-type two-dimensional layered thin film material and the p-type two-dimensional layered thin film material semiconductor layer, and cover each end of the n and p two-dimensional layered thin film material film layers; the top gate metal electrode layer is on the top gate dielectric layer, i.e., the top gate insulating layer, the top gate insulating layer includes silicon dioxide, aluminum oxide, hafnium dioxide or ITO; the thickness of the top gate insulating layer is 10-30 nanometers; the p-type semiconductor two-dimensional thin film material and the n-type semiconductor two-dimensional thin film material include black scale, transition metal chalcogenide or graphene. However, the gate insulating layer of the prior art still uses non-flexible three-dimensional materials such as aluminum oxide and hafnium dioxide, uses a traditional SOI substrate, and has not yet adopted a flexible packaging layer, which is not conducive to the realization of a fully flexible wearable photodetector; the light absorption band of the prior art is limited by the type of two-dimensional semiconductor material, and the response time is also limited by the electron mobility in the two-dimensional semiconductor material. Summary of the invention

[0005] The purpose of the present invention is to address the deficiencies of the prior art and to propose a flexible photodetector based on a graphene-two-dimensional material Schottky heterojunction.

[0006] In the first aspect, a flexible photodetector based on a graphene-two-dimensional material Schottky heterojunction is provided, comprising: a flexible substrate insulating layer, a two-dimensional thin film Schottky heterojunction, a metal interconnect wire and a top flexible packaging layer; Among them, a graphene layer, a two-dimensional material layer and a hexagonal boron nitride layer are arranged in sequence in a direction away from the flexible substrate insulating layer; the overlapping area of ​​the graphene layer, the two-dimensional material layer and the hexagonal boron nitride layer forms a two-dimensional thin film Schottky heterojunction; the metal interconnection wire includes a source metal interconnection wire, a drain metal interconnection wire and a gate metal interconnection wire; the source metal interconnection wire and the drain metal interconnection wire are connected to the graphene layer and the two-dimensional material layer respectively; the gate metal interconnection wire is connected to the hexagonal boron nitride layer; the top flexible packaging layer covers the surface of the flexible substrate insulating layer, and the top flexible packaging layer at the end of the metal interconnection wire is etched to expose the end of the metal interconnection wire.

[0007] Preferably, the flexible substrate insulating layer and the top flexible packaging layer are both made of polyethylene naphthalate material.

[0008] Preferably, the two-dimensional thin film Schottky heterojunction operates in a ballistic transport mode of electrons.

[0009] Preferably, the thickness of the graphene layer is less than the longitudinal mean free path of the graphene to achieve ballistic avalanche.

[0010] Preferably, the two-dimensional material layer is made of transition metal chalcogenide.

[0011] In a second aspect, a method for preparing a flexible photodetector based on a graphene-two-dimensional material Schottky heterojunction as described in any one of the first aspects is provided, comprising: Step 1, preparing a flexible substrate insulating layer; Step 2, spin-coating a photoresist on the insulating layer of the flexible substrate, and performing photolithography and development of a gold electrode pattern on the photoresist coating; placing the developed substrate into an electron beam evaporation device, performing evaporation growth of metal chromium and gold electrodes respectively, and then removing the photoresist to form a source metal interconnect wire and a drain metal interconnect wire; Step 3, forming a graphene layer on one side electrode of the flexible substrate insulating layer; Step 4: forming a two-dimensional material layer on the electrode on the other side of the flexible substrate insulating layer, wherein the two-dimensional material layer and the graphene layer have a first overlapping region; Step 5, forming a hexagonal boron nitride layer on the first overlapping region, wherein the hexagonal boron nitride layer and the first overlapping region have a second overlapping region; Step 6, forming a gate metal interconnection wire on the hexagonal boron nitride layer; Step 7: spin-coat a top flexible packaging layer on the surface of the flexible substrate insulating layer, and heat and cure it; then etch the top flexible packaging layer at the end of the metal interconnection wire to expose the metal interconnection wire.

[0012] Preferably, in step 2, the spin coating of the photoresist includes a low-speed spin coating stage and a high-speed spin coating stage, and the duration of the high-speed spin coating stage is longer than the duration of the low-speed spin coating stage.

[0013] Preferably, step 3 comprises: Step 3.1, rotating the PMMA support layer of the single atomic layer graphene grown by CVD on the copper foil substrate, and then etching away the copper foil substrate; Step 3.2, using a flexible substrate insulating layer to pick up the single atomic layer graphene from the water at a fixed point by wet transfer and place it on one side of the electrode; Step 3.3, performing photolithography and development on the single atomic layer graphene transferred to the substrate to expose the single atomic layer graphene outside the required area; Step 3.4: Place the sample in an ICP etcher to etch away the single atomic layer graphene outside the desired area.

[0014] Preferably, step 4 comprises: Step 4.1, obtaining a two-dimensional material film by mechanical exfoliation; Step 4.2, transferring the two-dimensional material film to the electrode on the other side of the flexible substrate insulating layer, and having a first overlapping region with the single atomic layer graphene previously transferred to the flexible substrate insulating layer 1 and remaining after etching; Step 4.3: Photolithography and development are performed on the two-dimensional material film transferred to the insulating layer of the flexible substrate to expose the two-dimensional material film outside the required area, and the exposed two-dimensional material is etched away using an ICP etcher.

[0015] The beneficial effects of the present invention are: 1. The present invention utilizes the zero bandgap characteristics of graphene to achieve light absorption in a wide spectral range from ultraviolet to infrared, breaking through the limitation of the narrow light absorption band of traditional photodetectors. In addition, the Fermi level of graphene can be adjusted by external voltage to achieve selective detection of the response wavelength. This adjustable band detection function enables the photodetector to adapt to a variety of optical detection scenarios, significantly improving its application flexibility and practicality.

[0016] 2. The present invention uses the Schottky heterojunction formed by graphene and two-dimensional materials, and utilizes the ballistic transport and ballistic avalanche effect of electrons to significantly improve the sensitivity and response speed of the photodetector. The ultra-high mobility of graphene and the fast relaxation time of hot electrons enable the detector to respond to light signals in a very short time, while the hot electron multiplication effect further enhances the signal conversion efficiency. Compared with traditional photodetectors, the present invention has significant advantages in the detection of weak light signals.

[0017] 3. The present invention uses fully flexible materials to construct the photodetector, so that it can maintain stable photoelectric performance when bent or deformed at a large angle. This fully flexible design not only solves the problem that traditional photodetectors cannot be made flexible and wearable, but also has good biocompatibility and is suitable for application scenarios such as wearable devices and health monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the structure of a flexible photodetector based on a graphene-two-dimensional material Schottky heterojunction; Figure 2 It curve of graphene / two-dimensional material Schottky heterojunction; Explanation of the reference numerals: flexible substrate insulating layer 1, graphene layer 2, two-dimensional material layer 3, hexagonal boron nitride layer 4, source metal interconnect wire 5, drain metal interconnect wire 6, gate metal interconnect wire 7, top flexible packaging layer 8. DETAILED DESCRIPTION

[0019] The present invention is further described below in conjunction with embodiments. The description of the following embodiments is only used to help understand the present invention. It should be noted that for ordinary persons in the art, without departing from the principle of the present invention, the present invention can also be modified in some ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0020] Embodiment 1: Graphene, a two-dimensional carbon atom film, exhibits strong light-matter interaction. Its flexible physical properties, excellent semiconductor electrical properties, and convenient micro-processing technology make it have great application potential in flexible photodetectors. The built-in electric field region formed by the heterojunction of graphene and other two-dimensional films is almost atomic in scale, and the ballistic avalanche effect formed by the ballistic transport of carriers can significantly improve the sensitivity of the detector.

[0021] Furthermore, Example 1 of the present application provides a flexible photodetector based on a graphene-two-dimensional material Schottky heterojunction, which utilizes the characteristics of flexibility and current ballistic transport of graphene and two-dimensional materials to solve the technical problems of existing photodetectors in terms of improving sensitivity, reducing noise, and achieving flexibility and wearability.

[0022] Specifically, Figure 1 As shown, the flexible photodetector based on graphene-two-dimensional material Schottky heterojunction includes: a flexible substrate insulating layer 1, a two-dimensional thin film Schottky heterojunction and a metal interconnection wire; Among them, a graphene layer 2, a two-dimensional material layer 3 and a hexagonal boron nitride layer 4 are arranged in sequence along the direction away from the flexible substrate insulating layer 1; the overlapping area of ​​the graphene layer 2, the two-dimensional material layer 3 and the hexagonal boron nitride layer 4 forms a two-dimensional thin film Schottky heterojunction to realize ballistic avalanche; the metal interconnection wire includes a source metal interconnection wire 5, a drain metal interconnection wire 6 and a gate metal interconnection wire 7; the source metal interconnection wire 5 and the drain metal interconnection wire 6 are connected to the graphene layer 2 and the two-dimensional material layer 3 respectively; the gate metal interconnection wire 7 is connected to the hexagonal boron nitride layer 4.

[0023] In addition, the detector also includes a top flexible packaging layer 8; the top flexible packaging layer 8 covers the surface of the flexible substrate insulating layer 1 to achieve a fully flexible wearable photodetector, and the top flexible packaging layer 8 at the end of the metal interconnection wire is etched to expose the end of the metal interconnection wire to connect the signal to the external circuit.

[0024] Compared with existing technologies, graphene's zero bandgap can achieve a very wide spectral response (other materials cannot do this), and has a high absorption capacity for wide-band light from ultraviolet to infrared, which is suitable for a variety of optical detection applications. Graphene has an ultra-high mobility, and electrons can pass through graphene unimpeded, which makes it respond quickly and can achieve high-frequency and high-speed photoelectric detection. The relaxation time of hot electrons in graphene is ultra-fast, and Auger scattering occurs, which has a multiplication effect, that is, more hot electrons above the Fermi surface are generated, thereby improving the efficiency of energy and signal conversion. The work function of graphene can be adjusted by voltage (other materials cannot do this), so the wavelength of response can be selected to achieve adjustable band photoelectric detection. Graphene has transparency, high mechanical strength and flexibility, and can maintain its photoelectric properties when bent or deformed, making it suitable for flexible electronic devices.

[0025] Therefore, the above-mentioned graphene-based flexible photodetector can be bent at a large angle, and the overall device has the advantages of ultra-thinness, flexibility and good biocompatibility. Its built-in photoconductive gain brings broadband wavelength sensitivity and high responsivity, and this inherent photoconductive gain allows design freedom, that is, the opaque and bulky readout electronics can be placed far away from the detector, so the transparency and size of the active sensing area can be preserved.

[0026] Embodiment 2: On the basis of Example 1, Example 2 of the present application provides a more specific flexible photodetector based on graphene-two-dimensional material Schottky heterojunction, comprising: a flexible substrate insulating layer 1, a two-dimensional thin film Schottky heterojunction, a metal interconnect wire and a top flexible packaging layer 8; Among them, a graphene layer 2, a two-dimensional material layer 3 and a hexagonal boron nitride layer 4 are sequentially arranged in a direction away from the flexible substrate insulating layer 1; the overlapping area of ​​the graphene layer 2, the two-dimensional material layer 3 and the hexagonal boron nitride layer 4 forms a two-dimensional thin film Schottky heterojunction; the metal interconnection wire includes a source metal interconnection wire 5, a drain metal interconnection wire 6 and a gate metal interconnection wire 7; the source metal interconnection wire 5 and the drain metal interconnection wire 6 are respectively connected to the graphene layer 2 and the two-dimensional material layer 3 to form a source and a drain; the gate metal interconnection wire 7 is connected to the hexagonal boron nitride layer 4 to form a gate; the top flexible encapsulation layer 8 covers the surface of the flexible substrate insulating layer 1, and the top flexible encapsulation layer 8 at the end of the metal interconnection wire is etched to expose the end of the metal interconnection wire. The signals generated at the Schottky heterojunction are respectively led out through the two metal contact electrodes.

[0027] The flexible substrate insulating layer 1 and the top flexible packaging layer 8 are both made of polyethylene naphthalate material, which can maintain its photoelectric performance when bent or deformed, and is suitable for flexible wearable application scenarios.

[0028] The two-dimensional thin film Schottky heterojunction operates in a ballistic transport mode of electrons.

[0029] The thickness of the graphene layer 2 is smaller than the longitudinal mean free path of the graphene (not exceeding 100 nanometers) to achieve ballistic avalanche, and thus the graphene layer 2 can reduce avalanche noise at a lower avalanche voltage.

[0030] The two-dimensional material layer 3 is made of transition metal chalcogenide.

[0031] In addition, the photoelectric response can be adjusted by the Fermi level of graphene. The infrared photosensitive materials of the prior art cannot adjust their Fermi level in real time through voltage, so they cannot adjust the Schottky barrier formed with the silicon substrate, so the photogenerated current cannot be adjusted in real time. The thermal electron scattering and multiplication effect in graphene, as well as its zero-bandgap energy band structure, are the reasons for responding to infrared light. The infrared photosensitive materials of the prior art only respond to infrared light through the size of their intrinsic bandgap, while graphene here uses the electron scattering effect to increase the low-energy infrared photogenerated electrons to an energy height that can be detected by the device, and has a current enhancement effect. Figure 2 As shown, compared with traditional devices, the detector prepared in the present application has higher sensitivity and faster response.

[0032] It should be noted that the parts in this embodiment that are the same or similar to those in Embodiment 1 can be referenced to each other and will not be described in detail in this application.

[0033] Embodiment 3: On the basis of Examples 1 and 2, Example 3 of the present application provides a method for preparing a flexible photodetector based on a graphene-two-dimensional material Schottky heterojunction, comprising: Step 1: Prepare a flexible substrate insulating layer 1.

[0034] In step 1 , polyethylene naphthalate (PEN) is used as the flexible substrate insulating layer 1 .

[0035] Step 2, spin-coating photoresist on the flexible substrate insulating layer 1, and performing photolithography and development of the gold electrode pattern on the photoresist coating; and placing the developed substrate into an electron beam evaporation device, performing evaporation growth of metal chromium and gold electrodes respectively, and then removing the photoresist to form a source metal interconnection wire 5 and a drain metal interconnection wire 6.

[0036] In step 2, the spin coating of the photoresist includes a low-speed spin coating stage and a high-speed spin coating stage, and the duration of the high-speed spin coating stage is longer than the duration of the low-speed spin coating stage.

[0037] Specifically, first, evenly spin-coat the photoresist on the flexible substrate insulating layer 1, and set the low speed and high speed stages to: 500rpm, 10s; 4000rpm, 60s. Thus, a photoresist coating of about 1 micron thickness is obtained, and then the gold electrode pattern is photolithography and developed. The developed substrate is placed in an electron beam evaporation device, and the metal chromium (Cr) and gold electrode (Au) are evaporated and grown respectively. Then the evaporated metal substrate is placed in acetone and isopropanol liquids in turn to wash away the remaining photoresist, and form source and drain metal interconnect wires, and then rinsed in deionized water.

[0038] Step 3: forming a graphene layer 2 on one side electrode of the flexible substrate insulating layer 1.

[0039] Step 3 includes: Step 3.1, rotating the PMMA support layer of the single atomic layer graphene grown by CVD on the copper foil substrate, and then etching away the copper foil substrate; Step 3.2, using a flexible substrate insulating layer 1 to pick up the single atomic layer graphene from the water at a fixed point by wet transfer and place it at one side of the electrode; Step 3.3, performing photolithography and development on the single atomic layer graphene transferred to the substrate to expose the single atomic layer graphene outside the required area; Step 3.4: Place the sample in an ICP etcher to etch away the single atomic layer graphene outside the desired area.

[0040] Step 4: forming a two-dimensional material layer 3 on the electrode on the other side of the flexible substrate insulating layer 1 , wherein the two-dimensional material layer 3 and the graphene layer 2 have a first overlapping region.

[0041] Step 4 includes: Step 4.1, obtaining a two-dimensional material film by mechanical exfoliation; Step 4.2, transferring the two-dimensional material film to the electrode on the other side of the flexible substrate insulating layer 1, and having a first overlapping region with the single atomic layer graphene previously transferred to the flexible substrate insulating layer 1 and remaining after etching; Step 4.3: perform photolithography and development on the two-dimensional material film transferred to the flexible substrate insulating layer 1 to expose the two-dimensional material film outside the required area, and etch away the exposed two-dimensional material with an ICP etcher.

[0042] Step 5: forming a hexagonal boron nitride layer 4 on the first overlapping region, wherein the hexagonal boron nitride layer 4 and the first overlapping region have a second overlapping region.

[0043] Step 5 includes: Step 5.1, after spin coating the hexagonal boron nitride film grown on the copper foil substrate with a PMMA support layer, the copper foil substrate is etched away, and the hexagonal boron nitride film is picked up from the water at a fixed point using a polyethylene naphthalate substrate by wet transfer, and placed on the first overlapping area, and forms a second overlapping area with the aforementioned etched single atomic layer graphene / two-dimensional material film; Step 5.2: Photolithography and development are performed on the hexagonal boron nitride film transferred to the substrate to expose the hexagonal boron nitride film outside the desired area, and the sample is placed in an ICP etcher to etch away the hexagonal boron nitride film outside the desired area.

[0044] Step 6: After the PMMA support layer is spin-coated on the hexagonal boron nitride layer 4, the gate pattern is written by electron beam direct writing and developed, and the developed device is placed in an electron beam evaporation device to perform evaporation growth of metal chromium (Cr) and gold electrode (Au). Then, the metal-evaporated substrate is placed in acetone and isopropanol liquids in turn to wash away the remaining photoresist and form a gate metal interconnection wire 7, and then rinsed in deionized water.

[0045] Step 7, spin-coating a top flexible packaging layer 8 on the surface of the flexible substrate insulating layer 1, and heat-curing it to encapsulate the manufactured photodetector; then, etching the top flexible packaging layer 8 at the end of the metal interconnection wire to expose the metal interconnection wire for interconnection with an external circuit.

[0046] Specifically, the method provided in this embodiment is a preparation method corresponding to the detectors provided in Embodiments 1 and 2. Therefore, the parts in this embodiment that are the same or similar to Embodiments 1 and 2 can be referenced to each other and will not be repeated in this application.

Claims

1. A flexible photodetector based on a graphene-two-dimensional material Schottky heterojunction, characterized in that: include: Flexible substrate insulating layer (1), two-dimensional thin film Schottky heterojunction, metal interconnect wires and top flexible packaging layer (8); A graphene layer (2), a two-dimensional material layer (3) and a hexagonal boron nitride layer (4) are sequentially arranged in a direction away from the flexible substrate insulating layer (1); the overlapping region of the graphene layer (2), the two-dimensional material layer (3) and the hexagonal boron nitride layer (4) forms a two-dimensional thin film Schottky heterojunction; the metal interconnection wire comprises a source metal interconnection wire (5), a drain metal interconnection wire (6) and a gate metal interconnection wire (7); the source metal interconnection wire (5) and the drain metal interconnection wire (6) are respectively connected to the graphene layer (2) and the two-dimensional material layer (3); the gate metal interconnection wire (7) is connected to the hexagonal boron nitride layer (4); the top flexible encapsulation layer (8) covers the surface of the flexible substrate insulating layer (1), and the top flexible encapsulation layer (8) at the end of the metal interconnection wire is etched to expose the end of the metal interconnection wire.

2. The flexible photodetector based on graphene-two-dimensional material Schottky heterojunction according to claim 1, characterized in that: The flexible substrate insulating layer (1) and the top flexible packaging layer (8) are both made of polyethylene naphthalate material.

3. The flexible photodetector based on graphene-two-dimensional material Schottky heterojunction according to claim 2, characterized in that: The two-dimensional thin film Schottky heterojunction operates in a ballistic transport mode of electrons.

4. The flexible photodetector based on graphene-two-dimensional material Schottky heterojunction according to claim 3, characterized in that: The thickness of the graphene layer (2) is smaller than the longitudinal mean free path of the graphene so as to achieve ballistic avalanche.

5. The flexible photodetector based on graphene-two-dimensional material Schottky heterojunction according to claim 4, characterized in that: The two-dimensional material layer (3) is made of transition metal sulfide compounds.

6. A method for preparing a flexible photodetector based on a graphene-two-dimensional material Schottky heterojunction as claimed in any one of claims 1 to 5, characterized in that: include: Step 1, preparing a flexible substrate insulating layer (1); Step 2, spin-coating a photoresist on the flexible substrate insulating layer (1), and performing photolithography and development of a gold electrode pattern on the photoresist coating; placing the developed substrate into an electron beam evaporation device, performing evaporation growth of metal chromium and gold electrodes respectively, and then removing the photoresist to form a source metal interconnection wire (5) and a drain metal interconnection wire (6); Step 3, forming a graphene layer (2) on one side electrode of the flexible substrate insulating layer (1); Step 4: forming a two-dimensional material layer (3) on the electrode on the other side of the flexible substrate insulating layer (1), wherein the two-dimensional material layer (3) and the graphene layer (2) have a first overlapping region; Step 5: forming a hexagonal boron nitride layer (4) on the first overlapping region, wherein the hexagonal boron nitride layer (4) and the first overlapping region have a second overlapping region; Step 6: forming a gate metal interconnection wire (7) on the hexagonal boron nitride layer; Step 7, spin coating a top flexible encapsulation layer on the surface of the flexible substrate insulating layer (1), and heating and curing; Then, the top flexible packaging layer at the end of the metal interconnection wire is etched to expose the metal interconnection wire.

7. The method for preparing a flexible photodetector based on a graphene-two-dimensional material Schottky heterojunction according to claim 6, characterized in that: In step 2, the spin coating of the photoresist includes a low-speed spin coating stage and a high-speed spin coating stage, and the duration of the high-speed spin coating stage is longer than the duration of the low-speed spin coating stage.

8. The method for preparing a flexible photodetector based on a graphene-two-dimensional material Schottky heterojunction according to claim 7, characterized in that: Step 3 includes: Step 3.1, rotating the PMMA support layer of the single atomic layer graphene grown by CVD on the copper foil substrate, and then etching away the copper foil substrate; Step 3.2, using a flexible substrate insulating layer (1) to pick up the single atomic layer graphene from the water at a fixed point by wet transfer and place it on one side of the electrode; Step 3.3, performing photolithography and development on the single atomic layer graphene transferred to the substrate to expose the single atomic layer graphene outside the required area; Step 3.4: Place the sample in an ICP etcher to etch away the single atomic layer graphene outside the desired area.

9. The method for preparing a flexible photodetector based on a graphene-two-dimensional material Schottky heterojunction according to claim 8, characterized in that: Step 4 includes: Step 4.1, obtaining a two-dimensional material film by mechanical exfoliation; Step 4.2, transferring the two-dimensional material film to the electrode on the other side of the flexible substrate insulating layer (1), and having a first overlapping region with the single atomic layer graphene previously transferred to the flexible substrate insulating layer (1) and remaining after etching; Step 4.3: photolithography and development are performed on the two-dimensional material film transferred to the flexible substrate insulating layer (1) to expose the two-dimensional material film outside the required area, and the exposed two-dimensional material is etched away using an ICP etcher.

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