A self-powered polarization-sensitive photodetector and its preparation method

Abstract

The present invention discloses a self-powered polarization-sensitive photodetector and a preparation method thereof. The method includes: preparing two-dimensional P-WS2 and N-GeAs2 nanosheets by the micro-mechanical exfoliation method; preparing a Mark with digital markings on a silicon oxide substrate by using ultraviolet lithography technology and coating technology; preparing a two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction on the silicon oxide substrate marked with Mark by the method of site-specific transfer; preparing a counter electrode pattern on the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction and evaporating electrodes; using an acetone solution to remove the glue to obtain a photodetector based on the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction. The photodetector designed by the present invention has a simple structure, high responsivity, high polarization sensitivity, low energy consumption, and fast response speed, providing a possibility for the realization of a self-powered polarization-sensitive photodetection system.

Description

Technical Field

[0001] The present invention relates to the technical field of optoelectronic detector preparation, and particularly relates to a self-powered polarization-sensitive optoelectronic detector and a preparation method thereof. Background Art

[0002] Under the background of the rapid development of information technology, optoelectronic detectors have penetrated into all aspects of our lives. For example, in communication, medical diagnosis, night vision, and remote sensing technologies, etc. However, since traditional optoelectronic detectors can only provide simple spectral information, it is very difficult to accurately identify targets in a concealed background. Optoelectronic detectors with polarization imaging capabilities can achieve accurate target recognition in complex environments. The core of polarization-sensitive light detection technology is to construct devices based on the crystal orientation of materials.

[0003] So far, most polarization-sensitive light detectors have been realized by applying a polarizer in front of the light detection device. With the rapid development of nanotechnology, it is crucial to reduce the size of the light detector and manipulate the polarization direction of light within a small volume. The previously reported polarization-sensitive light detectors based on one-dimensional nanowires require complex device patterning, which increases the difficulty of device preparation; moreover, the uneven aspect ratio of one-dimensional materials limits the diversification of device preparation.

[0004] In recent years, the rise of new in-plane anisotropic two-dimensional materials (such as black phosphorus, ReS2, etc.) has provided the possibility for the preparation of high-performance polarization-sensitive light detection devices. However, due to their low light absorption coefficient, polarization sensitivity, and air stability, the comprehensive performance of such devices is still far from practical applications. In addition, some polarization-sensitive optoelectronic detectors need to work in harsh and dangerous environments for a long time. Therefore, it is urgent to research and develop high-performance self-powered polarization-sensitive optoelectronic detectors. Summary of the Invention

[0005] In order to solve the above problems existing in the prior art and realize the construction of a high-performance self-powered polarization-sensitive optoelectronic detector, the present invention proposes a self-powered polarization-sensitive optoelectronic detector and a preparation method thereof. The self-powered polarization-sensitive optoelectronic detector is a high-performance self-powered polarization-sensitive optoelectronic detector based on a two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction, and its preparation method includes the following steps:

[0006] (1) Prepare WS2 single crystals and GeAs2 single crystals by chemical vapor transport method;

[0007] (2) Cut a single-polished silicon oxide wafer into small pieces, clean and dry it, and use it as a spare silicon oxide substrate; and use ultraviolet lithography technology and electron beam evaporation technology to prepare a Mark pattern with digital marks on the above silicon oxide substrate to obtain a silicon oxide substrate with Mark marks;

[0008] (3) Based on the WS2 single crystal and the GeAs2 single crystal, the exfoliated two-dimensional WS2 nanosheets and GeAs2 nanosheets are adhered to the PDMS substrate by a micro-mechanical exfoliation method;

[0009] (4) Manually transfer the two-dimensional WS2 nanosheets on the PDMS substrate to the silicon oxide substrate with Mark marks;

[0010] (5) Utilize a two-dimensional material transfer platform to prepare a two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction by a fixed-point transfer method:

[0011] First, respectively find the two-dimensional WS2 nanosheets on the silicon oxide substrate with Mark marks and the GeAs2 nanosheets on the PDMS substrate through a micro-focusing system, and move the two-dimensional GeAs2 nanosheets directly above the two-dimensional WS2 nanosheets;

[0012] Subsequently, slowly lower the PDMS substrate with the two-dimensional GeAs2 nanosheets until the two-dimensional GeAs2 nanosheets are partially attached to the two-dimensional WS2 nanosheets to form a two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction;

[0013] (6) Remove the organic matter on the surface of the two-dimensional sample during the transfer process by soaking in a hot acetone solution or annealing to obtain a two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction with a clean surface;

[0014] (7) Spin-coat PMMA glue on the silicon oxide substrate containing the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction and dry it on a hot plate;

[0015] (8) Use electron beam lithography technology to prepare a counter electrode pattern on the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction;

[0016] (9) Evaporate metal electrodes on the exposed silicon oxide substrate containing the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction by thermal evaporation;

[0017] (10) Remove the glue, soak the silicon oxide substrate with evaporated metal electrodes in a hot acetone solution, then use a dropper to peel off the metal layer outside the electrode area, and blow it dry with nitrogen to obtain a photodetector based on the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction.

[0018] Preferably, in step (2), the single-polished silicon oxide wafer is cut into small pieces, cleaned and dried, and used as a spare silicon oxide substrate, including:

[0019] The cut single-polished silicon oxide wafers are ultrasonically cleaned in ethanol, acetone, and isopropyl alcohol solutions for 10 - 15 min successively, and then dried with nitrogen to serve as the spare silicon oxide substrates.

[0020] Preferably, in step (6), the soaking temperature of the hot acetone solution is 50 - 70 °C, and the soaking time is 5 - 20 min; the annealing atmosphere is argon, the annealing temperature is 200 °C, and the annealing time is 10 - 20 min.

[0021] Preferably, in step (7), the spin coating of PMMA glue is divided into two times. The first spin coating speed is 800 - 1000 r / min, and the duration is 5 - 15 s; the second spin coating speed is 3000 - 4000 r / min, and the duration is 50 - 70 s; the drying temperature is 140 - 160 °C, and the drying time is 3 - 5 min.

[0022] Preferably, in step (8), the two counter electrode patterns are respectively fabricated on the P-WS2 nanosheets and N-GeAs2 nanosheets in the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction.

[0023] Preferably, in step (9), the evaporated metal electrode includes two layers of metals; among them, the first layer of metal is any one of titanium and chromium, with a thickness of 10 - 30 nm; the second layer of metal is any one of gold, silver, palladium, and platinum, with a thickness of 50 - 100 nm.

[0024] Preferably, in step (10), the soaking temperature of the hot acetone solution is 50 - 70 °C, and the soaking time is 5 - 20 min.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. The present invention realizes a high-performance self-powered polarization-sensitive photodetector based on the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction. By utilizing the excellent anisotropic optoelectronic properties and air stability of GeAs2, the high light absorption coefficient of WS2, and the built-in electric field in the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction to promote the separation of electron-hole pairs, etc., the construction of a self-powered polarization-sensitive photodetector is realized.

[0027] 2. The present invention realizes anisotropic self-driven light detection in the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction for the first time. Without applying any bias voltage, it shows a switching ratio as high as 10 3 and a responsivity as high as 1.38 AW -1Excellent photovoltaic performance; at the same time, by utilizing the characteristic of rapid carrier separation at the P-N junction interface, the device exhibits a relatively fast response speed (70 ms); in addition, the in-plane anisotropy ratio of the device's optical responsivity under polarized light can reach 2.25. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 FIG. is a schematic diagram of the device structure of the photodetector based on the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction provided by an embodiment of the present invention;

[0029] Figure 2 FIG. is the I-V curve of the photodetector based on the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction provided by an embodiment of the present invention under the illumination of a 532 nm laser with different optical power densities;

[0030] Figure 3 FIG. is the curve of the photocurrent versus time cycle of the photodetector based on the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction provided by an embodiment of the present invention under the illumination of a 532 nm laser with an optical power density of 19.9 mW·cm -2 ;

[0031] Figure 4 FIG. is the response time and decay time curves of the photodetector based on the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction provided by an embodiment of the present invention;

[0032] Figure 5 FIG. is the in-plane anisotropic optical responsivity of the photodetector based on the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction provided by an embodiment of the present invention under the illumination of a 532 nm laser with an optical power density of 19.9 mW·cm -2 ; DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] First of all, it should be introduced that GeAs2 is a stable P-type polarization-sensitive material. Different from the monoclinic structure of GeP studied previously, GeAs2 has an orthorhombic structure similar to black phosphorus. Combining the difference in electronegativity between Ge and As atoms breaks the inversion symmetry of odd layers of GeAs2. The above characteristics bring richer physical properties to two-dimensional GeAs2, including piezoelectricity, in-plane ferroelectricity, and in-plane anisotropy. Recently, the excellent in-plane anisotropic optical, electrical, and photodetection properties of two-dimensional GeAs2 have been confirmed, with a linear dichroism ratio as high as 2, and it is considered to have high application potential in the fields of electronics and optoelectronic devices. WS2 is a stable N-type semiconductor material with a relatively high light absorption coefficient. Combining two-dimensional GeAs2 and two-dimensional WS2 is expected to achieve high-performance in-plane anisotropic optoelectronic characteristics.

[0034] Secondly, the construction of a two-dimensional P-N junction with photovoltaic effect also makes it possible to have a self-powered photodetector. In addition, the P-N junction also has a high-quality heterojunction interface and efficient charge transport, is not limited by lattice mismatch, and can combine the advantages of different materials to realize the modulation of energy band structure and optoelectronic performance. Therefore, constructing a two-dimensional P-N van der Waals heterojunction is an effective method to realize a high-performance self-powered photodetector.

[0035] Therefore, by forming a planar P-N junction between two-dimensional GeAs2 and two-dimensional WS2, and utilizing the excellent in-plane anisotropic optoelectronic properties of two-dimensional GeAs2, as well as the built-in potential and interlayer recombination between the two materials to generate high-performance in-plane anisotropic photovoltaic performance, it is expected to obtain a self-powered polarization photodetector with excellent performance.

[0036] Based on this, the present invention designs a polarization-sensitive photodetector self-powered by a two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction and a preparation method thereof.

[0037] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in more detail below in conjunction with the drawings and embodiments of the present invention. It should be emphasized that the embodiments described herein are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, other related embodiments obtained by researchers in this field without creative efforts all fall within the scope of protection of the present invention.

[0038] Example 1

[0039] A preparation method of a self-powered polarization-sensitive photodetector specifically includes the following steps:

[0040] (1) Prepare WS2 single crystal and GeAs2 single crystal by chemical vapor transport method.

[0041] (2) Cut a 4-inch single-polished (single-polished surface) silicon oxide wafer into small pieces of 1×1 cm size, ultrasonically clean them in ethanol, acetone, and isopropyl alcohol solutions for 10 min, and then dry them with nitrogen to obtain a spare silicon oxide substrate; and use ultraviolet lithography technology and electron beam evaporation technology to prepare a digital-marked Mark pattern on the above silicon oxide substrate to obtain a silicon oxide substrate with a Mark mark.

[0042] (3) Based on the WS2 single crystal and GeAs2 single crystal, use the micro-mechanical exfoliation method to stick the exfoliated two-dimensional WS2 nanosheets and two-dimensional GeAs2 nanosheets on the PDMS substrate. The detailed exfoliation process refers to the prior art and will not be specifically introduced in this embodiment.

[0043] (4) Manually transfer the two-dimensional WS2 nanosheets on the PDMS substrate to the 1×1 cm Mark-labeled silica substrate.

[0044] (5) Use a two-dimensional material transfer platform to fabricate a two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction by means of fixed-point transfer.

[0045] First, use a microfocusing system to separately locate the two-dimensional WS2 nanosheets on the Mark-labeled silica substrate and the two-dimensional GeAs2 nanosheets on the PDMS substrate, and move the two-dimensional GeAs2 nanosheets directly above the two-dimensional WS2 nanosheets.

[0046] Subsequently, slowly lower the PDMS substrate with the two-dimensional GeAs2 nanosheets until the two-dimensional GeAs2 nanosheets partially adhere to the two-dimensional WS2 nanosheets, forming a two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction.

[0047] (6) Remove the organic matter on the surface of the two-dimensional sample brought about during the transfer process by soaking in a hot acetone solution or annealing; among them, the soaking temperature of the hot acetone solution is 70 °C, the soaking time is 10 min, the annealing atmosphere is high-purity argon, the annealing temperature is 200 °C, and the annealing time is 10 min; obtain a two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction with a clean surface.

[0048] (7) Spin-coat PMMA photoresist on the silica substrate containing the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction and dry it on a hot plate. The spin-coating of PMMA is carried out in two steps. The first spin-coating speed is 1000 r / min and the duration is 10 s; the second spin-coating speed is 3000 r / min and the duration is 60 s; then, dry it on a hot plate, the drying temperature is 150 °C, and the drying time is 3 min.

[0049] (8) Use electron beam lithography technology to fabricate counter electrode patterns on the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction. The two counter electrode patterns are respectively fabricated on the P-WS2 nanosheets and the N-GeAs2 nanosheets.

[0050] (9) Evaporate metal electrodes on the silica substrate of the exposed two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction by thermal evaporation. The first layer of metal evaporated is chromium with a thickness of 10 nm; the second layer of metal is gold with a thickness of 90 nm.

[0051] (10) Remove the photoresist; Immerse the silicon oxide substrate with evaporated metal electrodes in a hot acetone solution, then use a dropper to strip the metal layer outside the electrode area, and blow it dry with nitrogen to obtain a photodetector based on a two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction. Among them, the soaking temperature and soaking time of the hot acetone solution are the same as the parameters in step (6).

[0052] Example 2

[0053] This example provides another method for preparing a self-powered polarization-sensitive photodetector, which specifically includes the following steps:

[0054] (1) Prepare WS2 single crystals and GeAs2 single crystals by chemical vapor transport method.

[0055] (2) Cut a 4-inch single-polished silicon oxide wafer into small pieces of 1×1 cm, ultrasonically treat them in ethanol, acetone, and isopropyl alcohol solutions for 15 minutes, and then blow them dry with nitrogen as a spare silicon oxide substrate; and use ultraviolet lithography technology and electron beam evaporation technology to prepare a digital-marked Mark pattern on the above-mentioned silicon oxide substrate to obtain a silicon oxide substrate with a Mark mark.

[0056] (3) Use the micro-mechanical exfoliation method to stick the exfoliated two-dimensional WS2 nanosheets and two-dimensional GeAs2 nanosheets on the PDMS substrate.

[0057] (4) Manually transfer the two-dimensional WS2 nanosheets on the PDMS substrate to the 1×1 cm Mark-marked silicon oxide substrate.

[0058] (5) Use a two-dimensional material transfer platform to prepare a two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction by the method of fixed-point transfer.

[0059] First, respectively find the two-dimensional WS2 nanosheets on the silicon oxide substrate with a Mark mark and the two-dimensional GeAs2 nanosheets on the PDMS substrate through a micro-focusing system, and move the two-dimensional GeAs2 nanosheets directly above the two-dimensional WS2 nanosheets.

[0060] Subsequently, slowly lower the PDMS substrate with the two-dimensional GeAs2 nanosheets until the two-dimensional GeAs2 nanosheets partially adhere to the two-dimensional WS2 nanosheets to form a two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction.

[0061] (6) Remove the organic matter on the surface of the two-dimensional sample during the transfer process by soaking in a hot acetone solution or annealing. Among them, the soaking temperature of the hot acetone solution is 50 °C, the soaking time is 20 min, the annealing atmosphere is high-purity argon, the annealing temperature is 180 °C, and the annealing time is 20 min; obtain a two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction with a clean surface.

[0062] (7) Spin-coat PMMA photoresist on the silicon oxide substrate containing the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction and dry it on a hot plate. The spin-coating of PMMA is divided into two times. The first spin-coating speed is 800 r / min and the duration is 15 s; the second spin-coating speed is 4000 r / min and the duration is 60 s; then, dry it on a hot plate. The drying temperature is 150 °C and the drying time is 4 min.

[0063] (8) Use electron beam lithography technology to prepare counter electrode patterns on the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction. The two counter electrodes are respectively fabricated on the two-dimensional P-WS2 nanosheet and the N-GeAs2 nanosheet.

[0064] (9) Evaporate metal electrodes on the silicon oxide substrate of the exposed two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction by thermal evaporation. The first layer of metal evaporated is titanium with a thickness of 20 nm; the second layer of metal is gold with a thickness of 80 nm.

[0065] (10) Remove the photoresist; soak the silicon oxide substrate with evaporated metal electrodes in a hot acetone solution, then use a dropper to peel off the metal layer outside the electrode area, and blow it dry with nitrogen to obtain a photodetector based on the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction. Among them, the soaking temperature and soaking time of the hot acetone solution are the same as the parameters in step (6).

[0066] Another embodiment of the present invention also provides a self-powered polarization-sensitive photodetector, which can be prepared by the preparation method provided in the above-mentioned Embodiment 1 or Embodiment 2. Please refer to Figure 1 , Figure 1 is a schematic diagram of the device structure of the photodetector based on the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction proposed by the present invention. It includes a silicon oxide substrate, a PN junction formed by a two-dimensional N-WS2 nanosheet and a two-dimensional P-GeAs2 nanosheet, and a counter electrode. Among them, the silicon oxide substrate includes Si at the bottom layer and SiO2 on Si. The metal materials used for the counter electrode are chromium and gold. Linearly polarized light acts on the PN junction formed by the two-dimensional N-WS2 nanosheet and the two-dimensional P-GeAs2 nanosheet.

[0067] The present invention realizes a high-performance self-powered polarization-sensitive photodetector by using a two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction. By utilizing the excellent anisotropic optoelectronic properties and air stability of GeAs2, the high light absorption coefficient of WS2, and the built-in electric field of the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction to promote the separation of electron-hole pairs, etc., the construction of a self-powered polarization-sensitive photodetector based on the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction is realized. Moreover, this photodetector has characteristics such as high responsivity, high polarization sensitivity, low energy consumption, and fast response speed, providing the possibility for the realization of a self-powered polarization-sensitive photodetection system.

[0068] Device testing:

[0069] To verify the beneficial effects of the photodetector provided by the present invention, in this embodiment, a semiconductor optoelectronic test system equipped with a polarizer was used to test and verify the optoelectronic performance of the device.

[0070] Specifically, in this embodiment, a probe station (CRX-6.5K, Lake Shore) equipped with a semiconductor test system (2400, Keithley) was used to conduct optoelectronic performance tests, and a polarizer and a half-wave plate were configured at the laser exit to conduct optoelectronic performance tests at different wavelengths, different laser power densities, and different polarization angles. The test schematic diagram is as shown in the appendix Figures 2-5 as shown.

[0071] Among them, Figure 2 is the I-V curve of the photodetector based on the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction provided by the embodiment of the present invention under 532 nm laser illumination at different light power densities. Among them, the abscissa Voltage represents voltage, with the unit of V, and the ordinate Current represents current, with the unit of nA. It can be Figure 2 confirmed that the present invention has realized self-driven photodetection in the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction for the first time. Without applying any bias voltage, the open-circuit current at different light power densities is as high as 0.3 - 1.2 nA, having the characteristic of self-power supply.

[0072] Figure 3 is the curve of the photocurrent versus time cycle of the photodetector based on the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction provided by the embodiment of the present invention under 532 nm laser illumination with a light power density of 19.9 mW·cm -2 Among them, the abscissa Time represents time, with the unit of s, and the ordinate Current represents the output current, with the unit of nA. It can be Figure 3It can be seen that the device provided by the present invention has high stability, and the on-off ratio is as high as 10 3 .

[0073] Figure 4 FIG. is the response time and decay time curves of the photodetector based on the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction provided by the embodiment of the present invention. Among them, the abscissa Time represents time, the unit is s, and the ordinate Current represents the output current, the unit is nA. It can be seen from Figure 4 that by utilizing the characteristic of rapid separation of carriers at the P-N junction interface in the present invention, the device exhibits a relatively fast response speed (70 ms).

[0074] Figure 5 FIG. is the in-plane anisotropic optical responsivity of the photodetector based on the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction provided by the embodiment of the present invention under the illumination of a 532 nm laser with an optical power density of 19.9 mW·cm -2 . Among them, Photoresponsivity represents the optical responsivity, and its responsivity is as high as 1.38 AW -1 , and the in-plane anisotropy ratio is as high as 2.25. It is confirmed that the detector exhibits significantly different optical responsivities to polarized light with different polarization directions under the illumination of a 532 nm laser with an optical power density of 19.9 mW·cm -2 , that is, the present photodetector has in-plane anisotropic optical response to polarized light.

[0075] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. A preparation method of a self-powered polarization-sensitive photodetector, characterized in that, It includes the following steps: (1) Prepare WS2 single crystal and GeAs2 single crystal by chemical vapor transport method; (2) Cut the single-polished silicon oxide wafer into small pieces, clean and dry them, and use them as spare silicon oxide substrates; and use ultraviolet lithography technology and electron beam evaporation technology to prepare Mark patterns with digital marks on the above-mentioned silicon oxide substrates to obtain silicon oxide substrates with Mark marks; (3) Based on the WS2 single crystal and GeAs2 single crystal, use the micro-mechanical exfoliation method to stick the exfoliated two-dimensional WS2 nanosheets and GeAs2 nanosheets on the PDMS substrate; (4) Manually transfer the two-dimensional WS2 nanosheets on the PDMS substrate to the silicon oxide substrate with Mark marks; (5) Use a two-dimensional material transfer platform to prepare a two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction by a fixed-point transfer method: First, use a micro-focusing system to find the two-dimensional WS2 nanosheets on the silicon oxide substrate with Mark marks and the GeAs2 nanosheets on the PDMS substrate respectively, and move the two-dimensional GeAs2 nanosheets directly above the two-dimensional WS2 nanosheets; Subsequently, slowly lower the PDMS substrate with the two-dimensional GeAs2 nanosheets until the two-dimensional GeAs2 nanosheets are partially attached to the two-dimensional WS2 nanosheets to form a two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction; (6) Remove the organic matter on the surface of the two-dimensional sample brought by the transfer process by soaking in a hot acetone solution or annealing to obtain a two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction with a clean surface; (7) Spin-coat PMMA glue on the silicon oxide substrate containing the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction and dry it on a hot plate; (8) Use electron beam lithography technology to prepare counter electrode patterns on the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction; (9) Evaporate metal electrodes on the exposed silicon oxide substrate containing the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction by thermal evaporation; (10) Remove the glue, soak the silicon oxide substrate with evaporated metal electrodes in a hot acetone solution, then use a dropper to peel off the metal layer outside the electrode area, and dry it with nitrogen to obtain a photodetector based on the two-dimensional P-WS2 / N-GeAs2 van der Waals heterojunction.

2. The preparation method of the self-powered polarization-sensitive photodetector according to claim 1, characterized in that, In step (2), cutting the single-polished silicon oxide wafer into small pieces, cleaning and drying them, and using them as spare silicon oxide substrates includes: Ultrasonically clean the cut single-polished silicon oxide wafer in ethanol, acetone, and isopropanol solutions for 10-15 min, and then dry it with nitrogen to use it as a spare silicon oxide substrate.

3. The preparation method of the self-powered polarization-sensitive photodetector according to claim 1, characterized in that, In step (6), the soaking temperature of the hot acetone solution is 50-70 °C, and the soaking time is 5-20 min; the annealing atmosphere is argon, the annealing temperature is 200 °C, and the annealing time is 10-20 min.

4. The method for preparing a self-powered polarization-sensitive photodetector according to claim 1, characterized in that, In step (7), the spin coating of PMMA glue is divided into two times. The first spin coating speed is 800 - 1000 r / min, and the duration is 5 - 15 s; the second spin coating speed is 3000 - 4000 r / min, and the duration is 50 - 70 s; the drying temperature is 140 - 160 °C, and the drying time is 3 - 5 min.

5. The preparation method of the self-powered polarization-sensitive photodetector according to claim 1, wherein In step (8), two counter electrode patterns are respectively fabricated on two-dimensional P-WS2 nanosheets and N-GeAs2 nanosheets.

6. The preparation method of the self-powered polarization-sensitive photodetector according to claim 1, wherein, In step (9), the evaporated metal electrode includes two layers of metals; among them, the first layer of metal is any one of titanium and chromium, and the thickness is 10 - 30 nm; the second layer of metal is any one of gold, silver, palladium, and platinum, and the thickness is 50 - 100 nm.

7. The preparation method of the self-powered polarization-sensitive photodetector according to claim 1, characterized in that, In step (10), the immersion temperature of the hot acetone solution is 50 - 70 °C, and the immersion time is 5 - 20 min.

8. A self-powered polarization-sensitive photodetector, characterized in that, This self-powered polarization-sensitive photodetector is prepared by the method described in any one of claims 1 - 7.

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