A two-dimensional LiInP2Se6-based photodetector and a preparation method thereof

Abstract

A two-dimensional LiInP2Se6 photoelectric detector and a preparation method, the photoelectric detector uses two-dimensional material LiInP2Se6 as channel material, and uses silicon as a substrate, SiO2 as a dielectric layer, and performs photoelectric performance test by applying bias voltage on two side metal electrodes; the preparation method comprises the following steps: (1) transferring LiInP2Se6 nanometer film onto a silicon substrate; (2) uniformly spin coating photoresist on the surface of the silicon substrate to prepare a bottom electrode pattern; (3) positioning exposure is performed on the bottom electrode pattern, and then development is performed to expose the part needing to be evaporated electrode; (4) preparing a metal electrode. The photoelectric detector is prepared by using LiInP2Se6 as the channel material, and the photoelectric detector with high detection rate and wide band response is realized.

Description

Technical Field

[0001] This invention relates to a photodetector that converts optical signals into electrical signals, and more particularly to a photodetector based on the two-dimensional semiconductor LiInP2Se6 and its fabrication method, belonging to the technical field of two-dimensional materials and optoelectronic functional devices. Technical Background

[0002] Photodetectors are devices that convert optical signals into electrical signals and are widely used in communications, security inspection, medical imaging, and other fields. Photodetectors with high detectivity and wide-band detection capabilities have significant application value in environmental monitoring, optical communications, and chemical / biological sensing. Two-dimensional semiconductor materials are considered potential candidates for next-generation electronic and optoelectronic devices due to their excellent properties, such as layer-dependent tunable bandgap, smooth surface without dangling bonds, and ease of integration.

[0003] Currently, most traditional photodetectors are constructed based on elemental or binary two-dimensional materials. However, compared to elemental or binary two-dimensional materials, researchers have recently developed a series of novel multi-element selenium-phosphorus compound two-dimensional materials that exhibit unique physical and chemical properties, distinguishing them from traditional elemental and binary two-dimensional materials, and have become important candidate materials for realizing next-generation optoelectronic device applications.

[0004] Lithium indium selenide (LiInP2Se6) is a novel two-dimensional semiconductor material consisting of quaternary selenium-phosphorus compounds. Its crystal structure belongs to the trigonal crystal system. Space group. In each layer of the structure, Li, In, and P atoms occupy one-third of the vertices and the centers of the top and bottom faces of the hexagonal prism cell in an ordered manner, while Se atoms occupy positions above or below the centroid of the triangle formed by these atoms. The thickness of a single layer can reach [missing information]. The distance between layers is InSe6 polyhedra are arranged along the c-axis, while LiSe6 and P2Se6 polyhedra alternate along the c-axis. Therefore, along the c-axis, the layers alternate in an ABAB pattern. LiInP2Se6 possesses advantages such as good air stability, high resistivity, and suitable bandgap, making it a promising two-dimensional semiconductor optoelectronic detection material. Furthermore, LiInP2Se6 exhibits uniform melting, enabling high-throughput fabrication of large-size, high-quality crystals via chemical vapor transport (CVT) and Bridgman crucible lowering methods, which is beneficial for fabricating large-area LiInP2Se6 optoelectronic devices.

[0005] Current research indicates that LiInP₂Se₆ two-dimensional semiconductors can be used to fabricate direct neutron detectors. However, photodetectors based on LiInP₂Se₆ two-dimensional semiconductors have not yet been reported. Summary of the Invention

[0006] This invention addresses the shortcomings of existing photodetector technologies by conducting in-depth research and providing a two-dimensional semiconductor LiInP2Se6 photodetector with superior performance, along with a method for fabricating the photodetector.

[0007] This invention is based on a photodetector of two-dimensional semiconductor LiInP2Se6, and adopts the following technical solution:

[0008] The structure of this LiInP2Se6 photodetector, from bottom to top, consists of a Si substrate, a SiO2 dielectric layer, and a LiInP2Se6 nanofilm, with metal electrodes disposed on the LiInP2Se6 nanofilm. Two-dimensional LiInP2Se6 serves as the channel material, and Si as the substrate. Photoelectric performance is measured by applying a bias voltage across the metal electrodes.

[0009] The silicon substrate (silicon wafer) is a heavily doped P-type silicon wafer with a surface thickness of 280-300 nm of SiO2.

[0010] The thickness of the LiInP2Se6 nanofilm is 10–70 nm.

[0011] The metal electrodes are 3-5 nm chromium and 30-60 nm gold.

[0012] Due to the excellent optoelectronic properties of LiInP2Se6, two-dimensional LiInP2Se6 photodetectors have high detectivity and can achieve highly sensitive photodetection. Due to the existence of intrinsic defects in LiInP2Se6, two-dimensional LiInP2Se6 photodetectors can achieve photodetection in a wide wavelength range of 532-1064nm.

[0013] The above-mentioned method for fabricating a photodetector based on the two-dimensional semiconductor LiInP2Se6 includes the following steps:

[0014] (1) Transferring LiInP2Se6 nanofilms onto a silicon substrate;

[0015] The process of transferring the LiInP2Se6 nanofilm onto the silicon substrate is as follows: the LiInP2Se6 nanofilm is transferred onto the silicon substrate with a SiO2 surface using polydimethylsiloxane (PDMS) tape with the assistance of the transfer.

[0016] (2) Photoresist is uniformly spin-coated onto the surface of the silicon substrate to prepare the pattern of the bottom electrode;

[0017] The spin coating speed of the photoresist is 3500-4500 rpm, and the spin coating time is 30-40 seconds.

[0018] (3) Position and expose the pattern of the bottom electrode, and then develop it to expose the part of the electrode that needs to be vapor-deposited.

[0019] (4) Prepare the metal electrode;

[0020] The preparation process of the LiInP2Se6 nanofilm in step (1) is as follows:

[0021] ① Prepare the materials according to the molar ratio of LiInSe2:P:Se = 1:2:4, put them into a quartz tube, mix them evenly, sinter and seal the tube after vacuuming;

[0022] The vacuum level of the vacuum pump is 3 to 5 × 10⁻⁶. -4 Pa.

[0023] ② The quartz tube is heated in stages in a heating furnace to allow the raw materials to fully react.

[0024] The phased heating process involves first raising the temperature to 200-300℃ over 10-40 hours and holding it at that temperature for 10-20 hours; then raising the temperature to 500-600℃ over 10-30 hours and holding it at that temperature for 10-20 hours; and then raising the temperature to 800-1000℃ over 10-40 hours and holding it at that temperature for 10-30 hours.

[0025] ③ After the reaction is complete, the temperature is gradually reduced to obtain high-quality polycrystalline material;

[0026] The phased cooling process involves first cooling to 600-800℃ over 10-20 hours; then cooling to 500-700℃ over 10-40 hours; and finally cooling to room temperature over 10-30 hours. When the furnace body temperature drops to room temperature, the quartz tube is removed to obtain LiInP2Se6 polycrystalline material.

[0027] ④ Prepare the materials according to the molar ratio of LiInP2Se6:I2 = 1:0.006, put them into a quartz tube, mix them evenly, sinter and seal the tube after vacuuming; I2 is used as a transport agent.

[0028] The vacuum level of the vacuum pump is 3 to 5 × 10⁻⁶. -4 Pa.

[0029] ⑤ Heat the quartz tube in a CVT furnace, gradually increasing the temperature to allow the raw materials to react fully; gradually decrease the temperature to obtain large-size, high-quality crystals; set up high and low temperature zones to provide driving force for crystal growth; set up temperature field exchange to obtain crystals with cleaner surfaces.

[0030] The phased heating and cooling process is as follows: High temperature zone: First, the temperature is raised to 500-660℃ in 5-15 hours and held for 10-20 hours; then, the temperature is raised to 600-720℃ in 5-15 hours and held for 150-200 hours; then, the temperature is lowered to room temperature in 5-15 hours. Low temperature zone: First, the temperature is raised to 600-720℃ in 5-15 hours and held for 5-20 hours; then, the temperature is raised to 500-620℃ in 5-15 hours and held for 150-200 hours; then, the temperature is lowered to room temperature in 10-20 hours.

[0031] ⑥ After the reaction is complete, when the temperature of the CVT furnace body drops to room temperature, remove the quartz tube;

[0032] ⑦ Cut the quartz tube open (to avoid damage to the crystal caused by sudden changes in pressure inside and outside the quartz tube) and remove the LiInP2Se6 bulk single crystal;

[0033] The LiInP2Se6 grown using the CVT method has a smooth and clean surface, which can be directly used for subsequent testing.

[0034] ⑧ Mechanical exfoliation was performed on bulk LiInP2Se6 single crystals to prepare LiInP2Se6 nanofilms;

[0035] The process for preparing the LiInP2Se6 nanofilm is as follows: a bulk LiInP2Se6 single crystal is transferred to Scotch tape, and then the tape is repeatedly folded and pasted. As the number of pasting times increases, two-dimensional LiInP2Se6 nanosheets of different thicknesses are continuously peeled off. The thinner the LiInP2Se6 nanosheets, the lighter the color. As the color of the sample on the tape surface gradually becomes lighter, the bulk single crystal on the tape will be separated into thinner LiInP2Se6 nanofilms.

[0036] The LiInP2Se6 device prepared by the above method was tested for performance using a semiconductor testing system. Under a 532nm laser and a 5V bias, the device achieved a detectivity of 9.48 × 10⁻⁶. 12 Jones. At a bias voltage of 5V, the device exhibits photoresponse at wavelengths of 532nm, 635nm, 808nm, and 1064nm.

[0037] The LiInP2Se6 photodetector prepared by this invention has achieved outstanding performance compared with photodetectors made of other two-dimensional materials. The performance comparison of detectivity and on / off ratio is shown in Table 1.

[0038] Compared to phototransistors made of other two-dimensional materials (SiP2, Sb2Se3, MoS2, MoTe2, InSe), LiInP2Se6 photodetectors exhibit higher detectivity and sensitivity (see comparative literature: Strong In-Plane Anisotropic SiP2 as a IV-V 2D Semiconductor for Polarized Photodetection. ACS Nano 2021, 15, 20442-20452; Sodium-Mediated Epitaxial Growth of 2D Ultrathin Sb2Se3 Flakes for Broadband Photodetection. Adv. Funct. Mater. 2020, 30, 1909849; Ultrasensitive Photodetectors based on Monolayer MoS2. Nat. Nanotechnol. 2013, 8, 497-501; Highly Sensitive Visible to Infrared MoTe2 Photodetectors Enhanced by the Photogating Effect. Nanotechnology 2016, 27, 445201; High Performance and Bendable Few-layered InSe Photodetectors with Broad Spectral Response. Nano Lett. 2014, 14, 2800-2806). While achieving high sensitivity, the LiInP2Se6 photodetector can also achieve a wide-band optical response, making it a photodetector that combines high detectivity and wide-band photodetection.

[0039] Table 1. Performance Comparison of Photodetectors Made of Different Two-Dimensional Materials

[0040]

[0041] This invention utilizes the two-dimensional material LiInP2Se6 as the channel material to fabricate a photodetector with high detectivity and wide-band photoresponse, exhibiting ultra-sensitive detection capability and a wide-band optical response. This photodetector is based on the excellent optoelectronic properties of LiInP2Se6 itself, achieving a detectivity of up to 9.48 × 10⁻⁶. 12Jones; on the other hand, by utilizing the intrinsic defects of LiInP2Se6 to broaden the photoelectric response wavelength range, a wide-band photoelectric detection of 532-1064nm can be achieved. The high detectivity and wide detection range give two-dimensional LiInP2Se6 photodetectors a significant advantage in the field of photoelectric detection. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the structure of the two-dimensional LiInP2Se6 photodetector of the present invention.

[0043] Figure 2 This is an optical image of the two-dimensional LiInP2Se6 photodetector of this invention.

[0044] Figure 3 The image shows the photocurrent output characteristic curve of the two-dimensional LiInP2Se6 photodetector prepared in Example 1.

[0045] Figure 4 The image shows the time-resolved photocurrent curve of the two-dimensional LiInP2Se6 photodetector prepared in Example 1.

[0046] Figure 5 This is the detectivity of the two-dimensional LiInP2Se6 photodetector prepared in Example 1 under 532nm laser and 5V bias voltage.

[0047] Figure 6 The photocurrent output characteristic curves of the two-dimensional LiInP2Se6 photodetector prepared in Example 1 under 532, 635, 808 and 1064 nm lasers and 5V bias voltage are shown.

[0048] Among them: 1. Si substrate, 2. SiO2 dielectric layer, 3. LiInP2Se6 nanofilm, 4. metal electrode, 5. lasers of different wavelengths (532, 635, 808, 1064 nm). Detailed Implementation

[0049] This invention aims to provide a photodetector based on two-dimensional LiInP2Se6, which is as follows: Figure 1 As shown, its structure, from bottom to top, includes a Si substrate 1, a SiO2 dielectric layer 2, and a LiInP2Se6 nanofilm 3, on which a metal electrode 4 is disposed. The Si substrate (silicon wafer) 1 is a heavily doped p-type silicon wafer with a surface thickness of 280–300 nm of SiO2. The LiInP2Se6 nanofilm 3 has a thickness of 10–70 nm. The metal electrode 4 consists of 3–5 nm of chromium and 30–60 nm of gold.

[0050] Figure 2Optical images of the two-dimensional LiInP2Se6 photodetector of the present invention are shown. The electrode pattern is a pair of electrodes (metal electrodes 4) designed on a LiInP2Se6 thin film 3.

[0051] Using the two-dimensional material LiInP2Se6 as the channel material, photoelectric performance testing was conducted by applying a bias voltage across the two ends of the metal electrode, achieving ultrasensitive and wide-band photoelectric detection.

[0052] The specific fabrication process of the LiInP2Se6 photodetector of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0053] Example 1

[0054] This embodiment prepares a photodetector with a thickness of 55 nm LiInP2Se6 thin film.

[0055] (1) Prepare the materials according to the molar ratio of LiInSe2:P:Se=1:2:4, put them into a quartz tube and mix them evenly. Evacuate the tube to a vacuum degree of 3~5×10-4Pa, and then sinter and seal the tube.

[0056] (2) The quartz tube is heated in stages in a heating furnace to allow the raw materials to fully react.

[0057] First, raise the temperature to 230℃ over 30 hours and hold it at that temperature for 10 hours; then raise the temperature to 560℃ over 20 hours and hold it at that temperature for 10 hours; then raise the temperature to 940℃ over 30 hours and hold it at that temperature for 15 hours.

[0058] (3) After the reaction is complete, the temperature is gradually reduced to obtain high-quality polycrystalline material.

[0059] First, the temperature is lowered to 750℃ over 15 hours; then to 650℃ over 30 hours; and finally to room temperature over 25 hours. When the furnace body temperature drops to room temperature, the quartz tube is removed, yielding LiInP2Se6 polycrystalline material.

[0060] (4) Prepare the mixture according to the molar ratio of LiInP2Se6:I2 = 1:0.006, place it in a quartz tube and mix well. Then, evacuate the tube to a vacuum degree of 3-5 × 10⁻⁶. -4 After Pa, the tube is sintered and sealed.

[0061] (5) Heating the quartz tube in a CVT furnace

[0062] The raw materials are fully reacted through staged heating; large-size, high-quality crystals are obtained through staged cooling. During the staged heating and cooling process: high and low temperature zones are set up to provide driving force for crystal growth; temperature field exchange is set up to obtain crystals with cleaner surfaces.

[0063] The temperature rises and falls in stages. High temperature zone: First, the temperature rises to 560℃ in 6 hours and remains constant for 12 hours; then, the temperature rises to 660℃ in 6 hours and remains constant for 168 hours; then, the temperature drops to room temperature in 6 hours. Low temperature zone: First, the temperature rises to 660℃ in 6 hours and remains constant for 12 hours; then, the temperature drops to 560℃ in 6 hours and remains constant for 170 hours; then, the temperature drops to room temperature in 10 hours.

[0064] (6) After the reaction is complete, when the temperature of the CVT furnace body drops to room temperature, remove the quartz tube.

[0065] (7) First, use a file to make a small incision in the quartz tube, avoiding damage to the crystal caused by sudden pressure changes inside and outside the quartz tube. Take out the bulk LiInP2Se6 single crystal from the quartz tube.

[0066] (8) Select a high-quality LiInP2Se6 bulk single crystal, and then repeatedly fold and stick the tape (without removing it to stick the sample). As the sample color on the tape surface gradually lightens, the bulk single crystal on the tape will be separated into a thinner LiInP2Se6 nanofilm. Continue until a LiInP2Se6 nanofilm with a thickness of 55 nm is obtained.

[0067] (9) The LiInP2Se6 nanofilm prepared by the above method was transferred to a heavily doped P-type silicon wafer with a surface thickness of 290 nm using PDMS tape.

[0068] (10) Spin coat the sample obtained in step (9) above with AZ1500 photoresist and design and fabricate electrode patterns. The spin coater speed is 4000 rpm and the time is 35 s.

[0069] (11) Electrodes are prepared by exposing the electrode pattern using a laser direct writing lithography machine, and then developed using AZ400K developer to expose the electrode pattern.

[0070] (12) The above-obtained sample was used to prepare a metal electrode using existing thermal evaporation technology. First, 5 nm of chromium was deposited by evaporation, and then 60 nm of gold was deposited by evaporation.

[0071] Figure 3 The photocurrent output characteristic curves of the two-dimensional LiInP2Se6 photodetector prepared in this embodiment are presented. From... Figure 3 It can be seen that the photocurrent increases with increasing voltage.

[0072] Figure 4 The time-resolved photocurrent curves of the two-dimensional LiInP2Se6 photodetector prepared in this embodiment are presented. From... Figure 4 The switching characteristics of the photocurrent with laser irradiation can be seen.

[0073] The performance of the two-dimensional LiInP2Se6 photodetector prepared in this embodiment was tested using a semiconductor testing system. Figure 5 The detectivity of the two-dimensional LiInP2Se6 photodetector prepared in this embodiment under a 5V bias voltage, using a 532nm wavelength laser (see [link to documentation]). Figure 1 Using a light source as the excitation source, the device achieves a detectivity as high as 9.48 × 10⁻⁶. 12 Jones.

[0074] The performance of the two-dimensional LiInP2Se6 photodetector prepared in this embodiment was tested using a semiconductor testing system. Figure 6 The photocurrent output characteristic curves of the two-dimensional LiInP2Se6 photodetector prepared in this embodiment under a 5V bias voltage are presented. Lasers at 532, 635, 808, and 1064 nm were used (see [reference]). Figure 1 Using a light source as the excitation source, the device can achieve photoresponse at different wavelengths.

[0075] Example 2

[0076] This embodiment prepares a photodetector with a LiInP2Se6 thin film of thickness 30 nm. The preparation process is the same as that in Example 1, except that the parameters in steps (2), (3), (5), (8), (9), (10), and (12) are different. Specifically:

[0077] (2) The temperature is increased in stages. First, the temperature is increased to 200℃ in 25 hours and kept constant for 10 hours; then the temperature is increased to 600℃ in 30 hours and kept constant for 10 hours; then the temperature is increased to 1000℃ in 35 hours and kept constant for 15 hours.

[0078] (3) The temperature is reduced in stages. First, the temperature is reduced to 700℃ in 20 hours; then it is reduced to 500℃ in 15 hours; and then it is reduced to room temperature in 30 hours.

[0079] (5) Temperature rise and fall process: High temperature zone: First, the temperature rises to 660℃ in 10 hours and is kept constant for 15 hours; then the temperature rises to 700℃ in 10 hours and is kept constant for 180 hours; then the temperature drops to room temperature in 10 hours. Low temperature zone: First, the temperature rises to 700℃ in 10 hours and is kept constant for 15 hours; then the temperature drops to 600℃ in 10 hours and is kept constant for 182 hours; then the temperature drops to room temperature in 14 hours.

[0080] (8) A LiInP2Se6 nanofilm with a thickness of 30 nm was obtained.

[0081] (9) The prepared LiInP2Se6 nanofilm was transferred to a heavily doped P-type silicon wafer with a surface thickness of 280 nm using PDMS tape.

[0082] (10) Spin coater speed 3500 rpm, time 40s.

[0083] (12) First, 4nm chromium is deposited by vapor deposition, and then 50nm gold is deposited by vapor deposition.

[0084] Example 3

[0085] This embodiment prepares a photodetector with a LiInP2Se6 thin film of 60 nm thickness. The preparation process is the same as in Example 1, except that the parameters in steps (2), (3), (5), (8), (9), (10), and (12) are different. Specifically:

[0086] (2) The temperature is increased in stages. First, the temperature is increased to 300℃ in 20 hours and kept constant for 15 hours; then the temperature is increased to 500℃ in 25 hours and kept constant for 15 hours; then the temperature is increased to 900℃ in 30 hours and kept constant for 20 hours.

[0087] (3) The temperature is reduced in stages. First, the temperature is reduced to 600℃ in 20 hours; then it is reduced to 500℃ in 10 hours; then it is reduced to room temperature in 20 hours.

[0088] (5) Temperature rise and fall process: High temperature zone: First, the temperature rises to 620℃ in 15 hours and is kept constant for 20 hours; then the temperature rises to 720℃ in 15 hours and is kept constant for 160 hours; then the temperature drops to room temperature in 15 hours; Low temperature zone: First, the temperature rises to 720℃ in 15 hours and is kept constant for 20 hours; then the temperature drops to 620℃ in 15 hours and is kept constant for 162 hours; then the temperature drops to room temperature in 19 hours.

[0089] (8) A LiInP2Se6 nanofilm with a thickness of 60 nm was obtained.

[0090] (9) The prepared LiInP2Se6 nanofilm was transferred to a heavily doped P-type silicon wafer with a surface thickness of 300 nm using PDMS tape.

[0091] (10) Spin coater speed 4500 rpm, time 30s.

[0092] (12) First, 3nm chromium is deposited by vapor deposition, and then 30nm gold is deposited by vapor deposition.

[0093] Example 4

[0094] This embodiment prepares a photodetector with a LiInP2Se6 thin film of 70 nm thickness. The preparation process is the same as in Example 1, except that the parameters in steps (2), (3), (5), and (8) are different. Specifically:

[0095] (2) The temperature is increased in stages. First, the temperature is increased to 200℃ in 10 hours and kept constant for 20 hours; then the temperature is increased to 500℃ in 10 hours and kept constant for 20 hours; then the temperature is increased to 1000℃ in 40 hours and kept constant for 10 hours.

[0096] (3) The temperature is reduced in stages. First, the temperature is reduced to 600℃ in 10 hours; then it is reduced to 700℃ in 20 hours; and then it is reduced to room temperature in 15 hours.

[0097] (5) Temperature rise and fall process, high temperature zone: first, the temperature rises to 500℃ in 5 hours and is kept constant for 20 hours; then the temperature rises to 600℃ in 5 hours and is kept constant for 150 hours; then the temperature drops to room temperature in 8 hours.

[0098] Low temperature zone: First, raise the temperature to 600℃ in 5 hours and keep it constant for 5 hours; then lower the temperature to 500℃ in 5 hours and keep it constant for 150 hours; then lower it to room temperature in 15 hours.

[0099] (8) A LiInP2Se6 nanofilm with a thickness of 70 nm was obtained.

[0100] Example 5

[0101] This embodiment prepares a photodetector with a LiInP2Se6 thin film of 10 nm thickness. The preparation process is the same as in Example 1, except that the parameters in steps (2), (3), (5), and (8) are different. Specifically:

[0102] (2) The temperature is increased in stages. First, the temperature is increased to 300℃ in 40 hours and kept constant for 10 hours; then the temperature is increased to 530℃ in 20 hours and kept constant for 12 hours; then the temperature is increased to 800℃ in 10 hours and kept constant for 30 hours.

[0103] (3) The temperature is reduced in stages. First, the temperature is reduced to 800℃ in 12 hours; then it is reduced to 600℃ in 25 hours; and then it is reduced to room temperature in 10 hours.

[0104] (5) Temperature rise and fall process, high temperature zone: first, the temperature rises to 600℃ in 12 hours and is kept constant for 10 hours; then the temperature rises to 600℃ in 12 hours and is kept constant for 200 hours; then the temperature drops to room temperature in 5 hours.

[0105] Low temperature zone: First, the temperature is raised to 630℃ in 8 hours and kept constant for 10 hours; then it is lowered to 520℃ in 12 hours and kept constant for 200 hours; then it is lowered to room temperature in 20 hours.

[0106] (8) A LiInP2Se6 nanofilm with a thickness of 10 nm was obtained.

Claims

1. A two-dimensional LiInP2Se6 photodetector, characterized in that, From bottom to top, it comprises Si substrate, SiO2 dielectric layer, LiInP2Se6 nanometer film, and the LiInP2Se6 nanometer film is provided with a metal electrode, and the two-dimensional material LiInP2Se6 is used as channel material, and silicon is used as substrate, and SiO2 is used as dielectric layer, and bias is applied to the metal electrode to realize high-performance photoelectric detection.

2. A method for preparing the two-dimensional LiInP2Se6 photodetector of claim 1, characterized in that, The method comprises the following steps: (1) transferring the LiInP2Se6 nanometer film to the silicon substrate; (2) uniformly spin-coating photoresist on the surface of the silicon substrate to prepare a pattern of the bottom electrode; (3) positioning and exposing the pattern of the bottom electrode, and then developing to expose the part to be evaporated; (4) preparing the metal electrode.

3. The method of claim 2, wherein the method further comprises, The thickness of the LiInP2Se6 nanometer film is 10-70 nm.

4. The method of claim 2, wherein the method further comprises, The process of transferring the LiInP2Se6 nanometer film to the silicon substrate is to transfer the LiInP2Se6 nanometer film to a heavily doped P-type silicon wafer with a surface thickness of 280-300 nm SiO2 by using polydimethylsiloxane tape.

5. The method of claim 2, wherein the method further comprises, The rotation speed of the spin-coated photoresist is 3500-4500 rpm, and the spin-coating time is 30-40 seconds.

6. The method of claim 2, wherein the method further comprises, The metal electrode is 3-5 nm chromium and 30-60 nm gold.

7. The method of claim 2, wherein the method further comprises, The preparation process of the LiInP2Se6 nanometer film in step (1) is as follows: ①According to the molar ratio of LiInSe2:P:Se:=1:2:4, the raw materials are mixed and loaded into a quartz tube, and then the quartz tube is sintered after vacuumizing; ②The quartz tube is heated in a heating furnace in a phased manner to make the raw materials fully combine and react; The phased heating is as follows: firstly, the temperature is raised to 200-300 DEG C for 10-40 hours, and then kept constant for 10-20 hours; then the temperature is raised to 500-600 DEG C for 10-30 hours, and then kept constant for 10-20 hours; then the temperature is raised to 800-1000 DEG C for 10-40 hours, and then kept constant for 10-30 hours; then the temperature is lowered to 600-800 DEG C for 10-20 hours; then the temperature is raised to 500-700 DEG C for 10-40 hours; and then the temperature is lowered to room temperature for 10-30 hours; ③After the reaction is completed, the quartz tube is taken out when the temperature of the heating furnace body is lowered to room temperature, and LiInP2Se6 polycrystalline material is obtained; ④According to the molar ratio of LiInP2Se6:I2:=1:0.006, the raw materials are mixed and loaded into a quartz tube, and then the quartz tube is sintered after vacuumizing; wherein I2 is used as a transport agent; The vacuum degree of the vacuumizing is 3-5x10 -4 Pa; ⑤The quartz tube is heated in a CVT furnace in a phased manner to make the raw materials fully react; a high-temperature zone is set to provide driving force for crystal growth; and a temperature field exchange is set to obtain a crystal with a cleaner surface; The heating process is as follows: in the high-temperature zone, firstly, the temperature is raised to 500-600 DEG C for 5-10 hours, and then kept constant for 10-20 hours; then the temperature is raised to 600-700 DEG C for 5-10 hours, and then kept constant for 150-200 hours; and then the temperature is lowered to room temperature for 5-10 hours; in the low-temperature zone, firstly, the temperature is raised to 600-700 DEG C for 5-10 hours, and then kept constant for 5-10 hours; then the temperature is raised to 500-600 DEG C for 5-10 hours, and then kept constant for 150-200 hours; and then the temperature is lowered to room temperature for 10-20 hours. After the reaction is completed, when the CVT furnace body temperature drops to room temperature, the quartz tube is taken out, a small incision is first made in the quartz tube using a file, and during the process, damage to the crystal caused by sudden changes in the internal and external pressure of the quartz tube is avoided as much as possible; ⑦The LiInP2Se6 bulk single crystal is taken out, and the LiInP2Se6 surface obtained by using the CVT method is flat and clean, and can be directly used for subsequent testing; ⑧The LiInP2Se6 bulk single crystal is mechanically peeled to prepare a LiInP2Se6 nanofilm.

8. The method of claim 7, wherein the method further comprises, The LiInP2Se6 nanofilm preparation process is as follows: the LiInP2Se6 bulk single crystal is transferred to Scotch tape, and then the tape is repeatedly folded and pasted. As the number of pasting increases, different thicknesses of two-dimensional LiInP2Se6 nanosheets are continuously peeled off. The thinner the LiInP2Se6 nanosheet, the lighter the color. As the color of the sample on the surface of the tape gradually lightens, the bulk single crystal on the tape will be separated into a thinner LiInP2Se6 nanofilm.

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