Photoelectric detector and preparation method thereof

Abstract

The present invention provides a photodetector and a preparation method, which relates to the technical field of photoelectric devices; wherein the photodetector comprises: a substrate, a drain electrode layer, a P-type semiconductor layer, an N-type semiconductor layer and a source electrode layer; wherein the drain electrode layer and the source electrode layer form an asymmetric electrode structure; the substrate, the drain electrode layer, the P-type semiconductor layer, the N-type semiconductor layer and the source electrode layer contact each other from bottom to top to form a vertical transistor structure. The above-mentioned photodetector can provide a higher specific energy density and specific power density through the asymmetric electrode structure, reducing the energy consumption of the photodetector, so that it can operate for a longer time; the short vertical transistor channel reduces the possibility of defective capture of carriers, so that the short-circuit current, open-circuit voltage and photoelectric conversion efficiency of the photodetector can reach a larger value, therefore, the advantages of the asymmetric electrode and the vertical transistor are combined to improve the performance of the photodetector.

Description

Technical Field

[0001] The present invention relates to the technical field of optoelectronic devices, and in particular to a photoelectric detector and a preparation method thereof. Background Art

[0002] Photodetectors based on van der Waals heterostructures (vdWhs) play an important role in many areas of daily life, including photoelectric imaging, environmental monitoring, military communications, etc. In particular, self-driven photodetectors, which do not require the use of external power supplies, can greatly reduce the energy consumed in processing and moving information.

[0003] However, in the related art, most vdWhs-based photodetectors have defects such as low current density, low power conversion efficiency (PCE) and high power consumption, resulting in poor performance of the photodetectors.

[0004] Therefore, how to improve the performance of photodetectors is an urgent problem to be solved. Summary of the invention

[0005] The present invention provides a photodetector and a preparation method thereof, which are used to solve the defects of low current density, low PCE and high power consumption of the photodetector in the prior art, and improve the performance of the photodetector.

[0006] The present invention provides a photodetector, comprising: a substrate, a drain electrode layer, a P-type semiconductor layer, an N-type semiconductor layer and a source electrode layer; wherein:

[0007] The drain electrode layer and the source electrode layer form an asymmetric electrode structure;

[0008] The substrate, the drain electrode layer, the P-type semiconductor layer, the N-type semiconductor layer and the source electrode layer are in contact with each other from bottom to top to form a vertical transistor structure.

[0009] Optionally, the P-type semiconductor layer and the N-type semiconductor layer form a type II energy band arrangement structure on the energy band.

[0010] Optionally, the material of the P-type semiconductor layer is tungsten diselenide, and the material of the N-type semiconductor layer is molybdenum disulfide.

[0011] Optionally, an ohmic contact is formed between the drain electrode layer and the P-type semiconductor layer;

[0012] An ohmic contact is formed between the source electrode layer and the N-type semiconductor layer.

[0013] Optionally, the material of the drain electrode layer is metal; and the material of the source electrode layer is a highly light-transmitting material.

[0014] Optionally, the metal is gold; and the high light-transmittance material is graphyne.

[0015] Optionally, the photoelectric detector further comprises a test electrode, and the test electrode is used to test the detection performance of the photoelectric detector;

[0016] Wherein, the test electrode is in contact with the source electrode layer, and the material of the test electrode is metal.

[0017] The present invention also provides a method for preparing a photoelectric detector, comprising:

[0018] A drain electrode layer, a P-type semiconductor layer, an N-type semiconductor layer and a source electrode layer are sequentially prepared on a substrate;

[0019] Wherein, the drain electrode layer and the source electrode layer form an asymmetric electrode structure;

[0020] The substrate, the drain electrode layer, the P-type semiconductor layer, the N-type semiconductor layer and the source electrode layer are in contact with each other from bottom to top to form a vertical transistor structure.

[0021] Optionally, the material of the P-type semiconductor layer is tungsten diselenide, and the material of the N-type semiconductor layer is molybdenum disulfide;

[0022] The material of the drain electrode layer is metal; the material of the source electrode layer is a high light-transmittance material; wherein the metal is gold; and the high light-transmittance material is graphyne.

[0023] Optionally, the photodetector further comprises a test electrode, and the test electrode is used to test the detection performance of the photodetector; the test electrode is in contact with the source electrode layer, and the material of the test electrode is metal;

[0024] Wherein, the test electrode is prepared by the following method:

[0025] Evenly drop-coating a polyvinyl alcohol aqueous solution on a flat substrate, and waiting for the polyvinyl alcohol aqueous solution to solidify to obtain a first polyvinyl alcohol film;

[0026] The first polyvinyl alcohol film is removed from the substrate and covered on the test electrode, heated to a first preset temperature to melt the first polyvinyl alcohol film, and then cooled to a second preset temperature to obtain a second polyvinyl alcohol film wrapped with the test electrode;

[0027] Covering the target area of ​​the source electrode with the second polyvinyl alcohol film, heating to the first preset temperature to melt the second polyvinyl alcohol film into the polyvinyl alcohol aqueous solution, until the test electrode and the source electrode are attached to each other, and then removing the polyvinyl alcohol aqueous solution on the surface of the source electrode by a water dissolution method; the target area is the area of ​​the source electrode that is not in contact with the N-type semiconductor layer;

[0028] Wherein, the substrate is a polycarbonate plate, the mass fraction of the polyvinyl alcohol aqueous solution is 5% to 30%, the thickness of the first polyvinyl alcohol film is 200μm to 500μm, the first preset temperature is 80℃ to 100℃, and the second preset temperature is below 40℃.

[0029] The photodetector and preparation method provided by the present invention can provide higher specific energy density and specific power density through an asymmetric electrode structure, thereby reducing the energy consumption of the photodetector and allowing it to operate for a longer time; the short vertical transistor channel reduces the possibility of defective carrier capture, so that the short-circuit current, open-circuit voltage and photoelectric conversion efficiency of the photodetector can all reach larger values. Therefore, by combining the advantages of the asymmetric electrode and the vertical transistor, the performance of the photodetector is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 This is one of the structural schematic diagrams of the photoelectric detector provided by the present invention;

[0032] Figure 2 This is the second structural schematic diagram of the photoelectric detector provided by the present invention;

[0033] Figure 3 It is a schematic flow chart of a method for preparing a photoelectric detector provided by the present invention;

[0034] Figure 4 is a schematic diagram of the photovoltaic characteristic curve of the photoelectric detector provided by the present invention;

[0035] Figure 5 It is a schematic diagram of the photocurrent time response of the photodetector provided by the present invention. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In order to facilitate a clearer understanding of the embodiments of the present application, some relevant knowledge is first introduced as follows.

[0038] 1. Vertical transistor.

[0039] For vertical transistors, the channel length is effectively scaled to the nanometer level, which is determined by the thickness of the material sandwiched between the two electrodes. Two-dimensional transition-metal dichalcogenide (TMD) vertical transistors can achieve nearly ideal external quantum efficiency (EQE). These studies show that vertical transistors based on two-dimensional materials have the advantages of high switching speed, low power consumption, high state current, low operating voltage, etc., can be integrated on a large scale and have higher compatibility with flexible substrates.

[0040] 2. Asymmetric electrode.

[0041] Asymmetric electrode structure refers to the difference in the spatial configuration, material or preparation method of the electrode, which results in different electrical properties. Compared with symmetrical electrode structure, asymmetric electrode structure is more suitable for some special electrochemical applications.

[0042] The asymmetric electrode structure has the following significant advantages:

[0043] 1. Higher safety performance: Compared with the symmetrical electrode structure, the asymmetrical electrode structure can provide higher safety protection, reduce the internal reaction time and heat energy generated by the battery, reduce the internal pressure, and avoid safety hazards caused by overheating of the battery.

[0044] 2. High efficiency and energy consumption: Asymmetric electrode structure can provide higher specific energy density and specific power density, reduce the energy consumption of the battery, so that it can operate for a longer time.

[0045] 3. Optimize charging performance: Asymmetric electrode structure can optimize the charging performance of the battery, improve charging efficiency and reduce charging time.

[0046] In summary, the photodetector provided by the present invention optimizes the photoelectric performance of the van der Waals heterojunction through the vertical transistor structure of the asymmetric electrode, which opens up ideas for realizing high-performance photodetectors.

[0047] In practical applications, photodetectors can detect optical switching ratio, responsivity, photoelectric conversion efficiency, etc. Among them, the optical switching ratio can be calculated by the following formula (1):

[0048]

[0049] Among them, I ph Represents the current under light; I dark represents the current in the dark state.

[0050] The responsivity can be calculated by the following formula (2):

[0051]

[0052] Where R represents the responsiveness; I ph represents the current under light; P in Indicates the incident light power.

[0053] The photoelectric conversion efficiency can be calculated by the following formula (3):

[0054]

[0055] Where η represents the photoelectric conversion efficiency; P el，max Indicates the maximum output power; P in Represents the incident light power, P el，max =I ds ·V ds , where I ds represents the source-drain current, V ds Represents the source-drain voltage.

[0056] Combine the following Figures 1 to 5 The photoelectric detector and the preparation method provided by the present invention are described in detail. Figure 1 is one of the structural schematic diagrams of the photoelectric detector provided by the present invention, see Figure 1 As shown, the photodetector 100 includes: a substrate 101, a drain electrode layer 102, a P-type semiconductor layer 103, an N-type semiconductor layer 104 and a source electrode layer 105; wherein,

[0057] The drain electrode layer 101 and the source electrode layer 105 form an asymmetric electrode structure;

[0058] The substrate 101 , the drain electrode layer 102 , the P-type semiconductor layer 103 , the N-type semiconductor layer 104 , and the source electrode layer 105 are in contact with each other from bottom to top to form a vertical transistor structure.

[0059] The photodetector provided by the present invention can provide higher specific energy density and specific power density through an asymmetric electrode structure, thereby reducing the energy consumption of the photodetector and allowing it to operate for a longer time; the short vertical transistor channel reduces the possibility of defective carrier capture, so that the short-circuit current, open-circuit voltage and photoelectric conversion efficiency of the photodetector can all reach larger values. Therefore, by combining the advantages of the asymmetric electrode and the vertical transistor, the performance of the photodetector is improved.

[0060] Optionally, the P-type semiconductor layer and the N-type semiconductor layer form a type II energy band arrangement structure on the energy band.

[0061] In the embodiment of the present invention, the P-type semiconductor layer and the N-type semiconductor layer form a type II energy band arrangement structure on the energy band, which can realize self-power supply of the photodetector.

[0062] It should be noted that a semiconductor heterojunction is an interface formed by the contact surface of a crystal composed of two different materials. One of the materials is called a P-type semiconductor, which has excess holes; the other material is called an N-type semiconductor, which has excess free electrons. When the P-type semiconductor layer and the N-type semiconductor layer are combined by a specific method, a built-in electric field is formed at the interface.

[0063] Type II band alignment refers to the inversion of the boundary between the conduction band and the valence band in a semiconductor heterojunction, that is, the conduction band and the valence band overlap or misalign in spatial distribution. Type II band alignment forms an electron bound state in the heterojunction, which can restrict the movement of electrons and cause phenomena such as enhanced light absorption and photoluminescence.

[0064] Therefore, the type II band alignment structure has a wide range of applications in semiconductor heterojunctions. The type II band alignment structure can enhance the photoelectric conversion efficiency of the material. By introducing the type II band alignment structure in a semiconductor heterojunction, the energy level distribution of carriers can be changed, the recombination of carriers can be restricted, and the performance of devices such as solar cells and photodetectors can be improved.

[0065] In summary, the photodetector provided by the present invention has a high efficiency of photogenerated carriers because the P-type semiconductor layer and the N-type semiconductor layer form a type II energy band arrangement structure on the energy band; and because the photodetector is a vertical transistor structure, the probability of photogenerated carriers being captured by defects due to the short channel behavior of the vertical transistor is reduced, so that the response time can be shortened to the microsecond level. Through research, it is found that the optical switching ratio of the type II MoS2 / WSe2 van der Waals heterojunction with asymmetric electrodes under zero bias reaches 10 6 , the open circuit voltage reaches 0.57V.

[0066] Optionally, the material of the P-type semiconductor layer is tungsten diselenide (WSe2), and the material of the N-type semiconductor layer is molybdenum disulfide (MoS2).

[0067] Optionally, the selection rules of the drain electrode layer and the source electrode layer materials are as follows:

[0068] 1. An ohmic contact is formed between the drain electrode layer and the P-type semiconductor layer;

[0069] 2. An ohmic contact is formed between the source electrode layer and the N-type semiconductor layer.

[0070] In an embodiment of the present invention, the material selection rule for the drain electrode layer is that an ohmic contact needs to be formed between the drain electrode layer and the P-type semiconductor layer according to the energy band structure; the material selection rule for the source electrode layer is that an ohmic contact needs to be formed between the source electrode layer and the N-type semiconductor layer according to the energy band structure.

[0071] Optionally, the material of the drain electrode layer is metal; and the material of the source electrode layer is a highly light-transmitting material.

[0072] Optionally, the metal is gold (Au); and the high light-transmittance material is graphyne.

[0073] In practical applications, Graphene (source electrode layer) is a highly light-transmitting material that can form an ohmic contact with MoS2, and the light transmittance of Graphene reaches more than 95%. Au as the drain electrode layer can form an ohmic contact with WSe2.

[0074] Based on the work function of two-dimensional semiconductor materials, Au is used as the drain electrode layer, and graphyne with good conductivity and high transmittance is used as the source electrode layer to improve the photoelectric properties of the MoS2 / WSe2 heterojunction photodetector.

[0075] Figure 2 This is the second structural diagram of the photoelectric detector provided by the present invention, see Figure 2As shown, the photodetector 200 includes: a substrate 101, a drain electrode layer 102, a P-type semiconductor layer 103, an N-type semiconductor layer 104, a source electrode layer 105, and a test electrode 201; wherein,

[0076] The substrate 101, the drain electrode layer 102, the P-type semiconductor layer 103, the N-type semiconductor layer 104 and the source electrode layer 105 are connected to the Figure 1 To avoid repetition, they will not be described here.

[0077] Optionally, the test electrode 201 is used to test the detection performance of the photodetector 200;

[0078] The test electrode 201 is in contact with the source electrode layer 105 , and the material of the test electrode 201 is metal.

[0079] In the embodiment of the present invention, when the performance test of the photodetector 200 is performed, the test probe of the test instrument is used to test the photodetector 200. However, since the source electrode layer 105 (e.g., graphyne) is a non-metallic material, it cannot be in direct contact with the test probe. Therefore, it is necessary to prepare the test electrode 201 to contact with the test probe, so as to achieve the performance test of the photodetector 200.

[0080] It should be noted that since the material of the drain electrode layer is metal, the test probe of the testing instrument can directly contact the drain electrode layer; it is understandable that a test electrode in contact with the drain electrode layer can also be prepared, and the material of the test electrode is the same as that of the drain electrode layer.

[0081] Figure 3 is a schematic diagram of the process for preparing the photoelectric detector provided by the present invention, see Figure 3 As shown, the method includes step 301; wherein,

[0082] Step 301, sequentially preparing a drain electrode layer, a P-type semiconductor layer, an N-type semiconductor layer and a source electrode layer on a substrate;

[0083] Wherein, the drain electrode layer and the source electrode layer form an asymmetric electrode structure;

[0084] The substrate, the drain electrode layer, the P-type semiconductor layer, the N-type semiconductor layer and the source electrode layer are in contact with each other from bottom to top to form a vertical transistor structure.

[0085] Optionally, the material of the P-type semiconductor layer is tungsten diselenide (WSe2), and the material of the N-type semiconductor layer is molybdenum disulfide (MoS2);

[0086] The material of the drain electrode layer is metal; the material of the source electrode layer is a high light-transmittance material; wherein the metal is gold; and the high light-transmittance material is graphyne.

[0087] It should be noted that the construction process of the vertical transistor structure is as follows:

[0088] (1) Material preparation: A P-type semiconductor layer (such as WSe2), an N-type semiconductor layer (such as MoS2) and a source electrode layer (such as Graphene thin film) are obtained by mechanical stripping.

[0089] Specifically, first prepare multiple strips of tape, take a sheet of MoS2 and place it on a piece of tape, take another piece of clean tape and press it on it, tear it off, there will be a MoS2 sheet stuck on the tape, and then repeat the tearing operation 3 to 4 times to obtain a thinner MoS2, peel it off onto the polydimethylsiloxane (PDMS) on the glass slide and observe it under a microscope to find the MoS2 flakes of suitable layer thickness and size. Similarly, WSe2 and graphyne flakes can be obtained.

[0090] (2) Transfer. The P-type semiconductor layer, N-type semiconductor layer and source electrode layer are sequentially transferred to a substrate having a drain electrode layer (such as Au) using a dry transfer platform, with each layer stacked vertically and with the largest possible overlapping area.

[0091] Specifically, WSe2 on the PDMS film is first transferred to the Au electrode, and then the few layers of MoS2 on the PDMS film are transferred to WSe2, and a MoS2 / WSe2 heterojunction is formed by stacking. Finally, the graphyne flakes are transferred to MoS2. It should be noted that the Au electrode, WSe2, MoS2 and graphyne overlap as much as possible, and the Au electrode only contacts with WSe2, graphyne only contacts with MoS2, and WSe2 and MoS2 are in contact.

[0092] In another implementation of the present invention, the P-type semiconductor layer, the N-type semiconductor layer and the source electrode layer may be prepared by using a material preparation method such as vapor deposition, etc. The present invention is not limited to this.

[0093] The preparation method of the photodetector provided by the present invention can provide higher specific energy density and specific power density through an asymmetric electrode structure, thereby reducing the energy consumption of the photodetector, so that it can operate for a longer time; the short vertical transistor channel reduces the possibility of defective carrier capture, so that the short-circuit current, open-circuit voltage and photoelectric conversion efficiency of the photodetector can all reach larger values. Therefore, by combining the advantages of the asymmetric electrode and the vertical transistor, the performance of the photodetector is improved.

[0094] In the embodiment of the present invention, the step 301 of sequentially preparing a drain electrode layer, a P-type semiconductor layer, an N-type semiconductor layer and a source electrode layer on a substrate can be specifically implemented in the following manner:

[0095] Step 1), pre-treat the substrate.

[0096] Specifically, the substrate is a silicon wafer with a silicon dioxide (SiO2) insulating layer, and the substrate needs to be cleaned to ensure a clean and appropriately sized substrate. The processing method is as follows:

[0097] First of all, it should be noted that the specifications, time, etc. involved in the following embodiments are only for illustration and the present invention is not limited thereto.

[0098] 1. Cut a 4-inch silicon wafer into squares with a length and width of 1 cm.

[0099] 2. Place them on the cleaning rack in order and use acetone, isopropyl alcohol and anhydrous ethanol for ultrasonic cleaning in turn. The general time is 10 minutes (min) to remove organic matter and other residues attached to the surface of the silicon wafer.

[0100] 3. After cleaning, blow dry with high-purity nitrogen.

[0101] Step 2), prepare the drain electrode.

[0102] Specifically, on a clean substrate, a drain electrode is prepared by using ultraviolet etching, thermal evaporation and other micro-nano technologies, wherein the material of the drain electrode is Au.

[0103] The method for preparing the drain electrode is as follows:

[0104] 1. Ultraviolet light etching.

[0105] a) Spin coating photoresist. Spin coating photoresist on the substrate using a coating machine, which is set to spin at a low speed of 800 revolutions per minute (rpm) for 10 seconds (s); then at a speed of 3000 rpm for 20 seconds; and finally at a high speed of 6000 rpm for 20 seconds to evenly distribute the photoresist (model: AZ-5214) on the substrate.

[0106] b) Glue baking: Place the substrate coated with the photoresist on a glue baking machine preheated to 100° C. and bake for 1 minute to remove the organic solvent in the photoresist.

[0107] c) Exposure: The substrate with the photoresist spun on it is exposed to a specific pattern. First, the electrode pattern of a specific shape and size is drawn using KLayout software and saved in JPG format. Then, a maskless photolithography machine is used for exposure, and the exposure area is the drawn electrode pattern.

[0108] d) Development: The exposed substrate with the photoresist is developed, and the exposed pattern is developed with a developer (model: 2.38% AZ300MIF), and the development time is, for example, 30 seconds, and then rinsed with ionized water and dried with high-purity nitrogen to obtain a substrate with a specific pattern.

[0109] It should be noted that, in another implementation of the present invention, a substrate with a specific pattern may be obtained by using a method for preparing electrode shapes such as electron beam lithography.

[0110] 2. Thermal evaporation electrode.

[0111] a) Metal evaporation: Place the substrate with a specific pattern in a high vacuum coating machine to thermally evaporate a metal film with a thickness of 40nm.

[0112] b) Gold washing: Place the silicon wafer with the metal film evaporated in an acetone solution and shake it gently to remove the excess photoresist on the silicon wafer and the gold film attached to the photoresist, and a drain electrode with a specific shape can be obtained.

[0113] It should be noted that, in another implementation of the present invention, the drain electrode can also be obtained by using a method for preparing an electrode thin film such as electron beam evaporation.

[0114] Step 3) prepare a P-type semiconductor layer, an N-type semiconductor layer and a source electrode layer, and transfer them sequentially to a substrate with a drain electrode layer through a transfer platform to form a heterojunction and a completely vertical transistor with gold and graphyne as asymmetric electrode layers.

[0115] Step 4: Prepare a test electrode corresponding to the source electrode layer, wherein the test electrode is in contact with the source electrode layer and the material of the test electrode is metal.

[0116] In practical applications, polyvinyl alcohol (PVA) may be used to transfer the test electrode to a target region of the source electrode layer.

[0117] Optionally, the test electrode is prepared by the following steps:

[0118] 1. Evenly drop a polyvinyl alcohol aqueous solution on a flat substrate, and wait for the polyvinyl alcohol aqueous solution to solidify to obtain a first polyvinyl alcohol film;

[0119] 2. removing the first polyvinyl alcohol film from the substrate and covering the test electrode, heating the first polyvinyl alcohol film to a first preset temperature to melt the first polyvinyl alcohol film, and then cooling the first polyvinyl alcohol film to a second preset temperature to obtain a second polyvinyl alcohol film wrapped with the test electrode;

[0120] 3. Covering the target area of ​​the source electrode with the second polyvinyl alcohol film, heating to the first preset temperature to melt the second polyvinyl alcohol film into the polyvinyl alcohol aqueous solution, until the test electrode and the source electrode are attached to each other, and then removing the polyvinyl alcohol aqueous solution on the surface of the source electrode by a water dissolution method; the target area is the area of ​​the source electrode that is not in contact with the N-type semiconductor layer;

[0121] Wherein, the substrate is a polycarbonate plate, the mass fraction of the polyvinyl alcohol aqueous solution is 5% to 30%, and in practical applications, the mass fraction of the polyvinyl alcohol aqueous solution is preferably 20%;

[0122] The thickness of the first polyvinyl alcohol film is 200 μm to 500 μm. In practical applications, the thickness of the first polyvinyl alcohol film is preferably 300 μm.

[0123] The first preset temperature is 80°C to 100°C, and the second preset temperature is below 40°C; in practical applications, the first preset temperature is preferably 95°C.

[0124] Figure 4 Schematic diagram of the photovoltaic characteristic curve of the photoelectric detector provided by the present invention. Figure 4 As shown, Figure 4 The current-voltage characteristic curves in the dark state and under different illumination intensities of 405 laser are shown.

[0125] The horizontal axis represents the source-drain voltage V ds (V), the ordinate represents the source-drain current I ds (nA). As the light intensity increases, the current gradually increases. When the light intensity is 44.3mW / cm2, the open circuit voltage is 0.57V and the short circuit current is 275nA.

[0126] Figure 5 Schematic diagram of the photocurrent time response of the photodetector provided by the present invention. Figure 5 As shown, Figure 5 The photocurrent-time curve is shown.

[0127] The horizontal axis is time and the vertical axis is source-drain current. When no bias voltage and gate voltage are applied, the current changes with the light intensity, that is, the photocurrent generated under light. The photocurrent has a good waveform and can quickly return to its original state. As the number of photocarriers increases, it gradually increases with the increase of incident power intensity. In addition, the device has a high on-off ratio of 10 at zero bias voltage. 6 , indicating that it has broad application prospects in high-performance, low-power optical logic circuits.

[0128] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A photoelectric detector, characterized in that: include: substrate, drain electrode layer, P-type semiconductor layer, N-type semiconductor layer and source electrode layer; wherein, The drain electrode layer and the source electrode layer form an asymmetric electrode structure; The substrate, the drain electrode layer, the P-type semiconductor layer, the N-type semiconductor layer and the source electrode layer are in contact with each other from bottom to top to form a vertical transistor structure; The P-type semiconductor layer and the N-type semiconductor layer form a type II energy band arrangement structure on the energy band; The material of the P-type semiconductor layer is tungsten diselenide, and the material of the N-type semiconductor layer is molybdenum disulfide; An ohmic contact is formed between the drain electrode layer and the P-type semiconductor layer; An ohmic contact is formed between the source electrode layer and the N-type semiconductor layer; The material of the drain electrode layer is metal; the metal is gold; the material of the source electrode layer is a high light-transmittance material; the high light-transmittance material is graphyne; The photodetector is used to improve the detection performance of the optical switching ratio and the open circuit voltage under zero bias.

2. The photodetector according to claim 1, characterized in that: The photoelectric detector further comprises a test electrode, and the test electrode is used to test the detection performance of the photoelectric detector; Wherein, the test electrode is in contact with the source electrode layer, and the material of the test electrode is metal.

3. A method for preparing a photoelectric detector, characterized in that: include: A drain electrode layer, a P-type semiconductor layer, an N-type semiconductor layer and a source electrode layer are sequentially prepared on a substrate; Wherein, the drain electrode layer and the source electrode layer form an asymmetric electrode structure; The substrate, the drain electrode layer, the P-type semiconductor layer, the N-type semiconductor layer and the source electrode layer are in contact with each other from bottom to top to form a vertical transistor structure; The P-type semiconductor layer and the N-type semiconductor layer form a type II energy band arrangement structure on the energy band; An ohmic contact is formed between the drain electrode layer and the P-type semiconductor layer; An ohmic contact is formed between the source electrode layer and the N-type semiconductor layer; The material of the P-type semiconductor layer is tungsten diselenide, and the material of the N-type semiconductor layer is molybdenum disulfide; The material of the drain electrode layer is metal; the metal is gold; the material of the source electrode layer is a high light-transmittance material; the high light-transmittance material is graphyne; The photodetector is used to improve the detection performance with respect to the optical switching ratio and the open circuit voltage under zero bias voltage.

4. The method for preparing a photoelectric detector according to claim 3, characterized in that: The photodetector further comprises a test electrode, which is used to test the detection performance of the photodetector; the test electrode is in contact with the source electrode layer, and the material of the test electrode is metal; Wherein, the test electrode is prepared by the following method: Evenly drop-coating a polyvinyl alcohol aqueous solution on a flat substrate, and waiting for the polyvinyl alcohol aqueous solution to solidify to obtain a first polyvinyl alcohol film; The first polyvinyl alcohol film is removed from the substrate and covered on the test electrode, heated to a first preset temperature to melt the first polyvinyl alcohol film, and then cooled to a second preset temperature to obtain a second polyvinyl alcohol film wrapped with the test electrode; Covering the target area of ​​the source electrode layer with the second polyvinyl alcohol film, heating to the first preset temperature to melt the second polyvinyl alcohol film into the polyvinyl alcohol aqueous solution, until the test electrode and the source electrode layer are attached to each other, and then removing the polyvinyl alcohol aqueous solution on the surface of the source electrode layer by a water dissolution method; the target area is the area of ​​the source electrode layer that is not in contact with the N-type semiconductor layer; Wherein, the substrate is a polycarbonate plate, the mass fraction of the polyvinyl alcohol aqueous solution is 5% to 30%, the thickness of the first polyvinyl alcohol film is 200μm to 500μm, the first preset temperature is 80℃ to 100℃, and the second preset temperature is below 40℃.

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