Preparation method of two-dimensional material photoelectric detector

Abstract

The invention relates to a preparation method of a two-dimensional material photoelectric detector, and the method comprises the following steps: transferring a two-dimensional material to a substrate comprising a grid electrode, a source electrode and a drain electrode through wet transfer, exciting oxygen through ultraviolet light to generate ozone, and carrying out the first patterning of the two-dimensional material, thereby obtaining a substrate comprising a patterned two-dimensional material layer; the two-dimensional material photoelectric detector is prepared by the following steps: firstly, carrying out first-time patterning treatment on a P3HT / [6, 6]-phenyl-C61-methyl butyrate PCBM layer, then spin-coating a P3HT / [6, 6]-phenyl-C61-methyl butyrate PCBM layer, and carrying out second-time patterning treatment on the P3HT / PCBM layer by utilizing ultraviolet light to excite oxygen to generate ozone, thereby obtaining the two-dimensional material photoelectric detector. According to the preparation method disclosed by the invention, high-quality Van der Waals contact between the large-area and uniform two-dimensional material layer and the metal electrode is realized; and the performance uniformity, the yield and the long-term stability of the two-dimensional material photoelectric detector are improved.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic device technology, and specifically relates to a method for preparing a two-dimensional material photodetector. Background Technology

[0002] A photodetector is a semiconductor device that converts light signals (photon energy) into electrical signals (current or voltage). It plays an indispensable role in various fields such as optical communication, biosensing, and environmental monitoring, greatly promoting the development of nanoelectronics and nano-optoelectronics. Since the advent of graphene, two-dimensional (2D) materials have received widespread attention from scientists. Two-dimensional materials possess excellent electronic and optical properties and are widely used in optoelectronic devices. A two-dimensional material photodetector is a novel type of photodetector that utilizes atomically thin two-dimensional materials as its core photosensitive element. Its core material is only one or a few atomic layers thick (e.g., graphene), possessing unique advantages such as ultra-wideband spectral response, ultrathinness, ultralight weight, flexibility, extremely high response speed, powerful photoelectric modulation capabilities, and ease of integration. This is the most fundamental difference between it and traditional silicon-based or III-V group detectors.

[0003] Currently, the main methods for fabricating two-dimensional photodetectors include mechanical exfoliation and liquid-phase exfoliation. However, both methods suffer from problems such as inability to scale up production, residual photoresist affecting photoelectric performance, and poor material quality, failing to fundamentally solve the problem of mass production of photodetectors. More specifically, mechanical exfoliation suffers from the randomness of the physical process, relying on external physical forces (tape adhesion) to overcome interlayer van der Waals forces. This is completely random and uncontrollable, making it impossible to predict the size, thickness, and position of the torn flakes. Although semi-automated tools exist, the core remains a trial-and-error process, requiring manual searching for suitable flakes under a microscope, making parallel processing impossible. Even with automation, the inherent randomness of the physical process remains unchanged, resulting in extremely low yields. Attempting to increase yield often sacrifices material selectivity (resulting in a large number of useless thick flakes) and quality. Therefore, mechanical exfoliation cannot currently achieve large-scale production. Secondly, CVD growth combined with photolithography yields materials of poor quality, and the transfer process is complex, leaving residual photoresist. The impact of residual photoresist is mainly divided into two categories: "chemical doping" and "physical contamination," which reduces the electrical and optical performance of the detector. The ultimate solution is direct growth on insulating substrates (such as SiO2 / Si) without the need for transfer. However, insulating substrates have low catalytic activity, making growth difficult, and it's challenging to balance nucleation density, growth rate, and crystal quality. Furthermore, liquid-phase exfoliation methods result in poor material quality, low performance, and poor uniformity. The high-energy ultrasound during exfoliation generates cavitation bubbles, and the localized high temperature and pressure during rupture severely damage the lattice structure of the two-dimensional material, generating numerous defects and leading to small, non-uniform sizes and a high edge proportion. The small size of nanosheets implies a high proportion of unsaturated and highly reactive edge atoms, which become charge recombination centers, resulting in poor device performance. To address these issues, there is an urgent need to develop gentler exfoliation methods. However, the challenge lies in finding universally applicable intercalating ions and electrolyte systems, as well as controlling the degree of intercalation to avoid irreversible structural damage.

[0004] In the prior art, patent CN118825106A discloses a two-dimensional inorganic / inorganic van der Waals heterojunction photodetector and its fabrication method. It sequentially sets a two-dimensional MoSe material layer, a two-dimensional MoS2 material layer and a gold thin film on a substrate. The two-dimensional material layers are transferred to the substrate by dry transfer. The two two-dimensional material layers form a vertical structure of van der Waals heterojunction to achieve van der Waals contact. The gold thin film and the heterojunction also have van der Waals metal contact. However, in practical applications, this technical solution cannot be mass-produced.

[0005] Hui Ren et al. (Nanomaterials, 2025, 15(11), 787) used a high-purity MoS2 target to deposit patterned MoS2 films through a mask. However, the pattern precision obtained by this method is low and the size is limited.

[0006] Therefore, how to provide a method for mass-producing two-dimensional material photodetectors without photoresist contamination is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] The technical problem to be solved by this invention is to provide a method for fabricating a two-dimensional material photodetector, fundamentally solving the following problems: avoiding chemical doping and physical damage to the surface of two-dimensional materials caused by complex photoresist processes; reducing the complexity and cost of the integration process of high-quality two-dimensional materials and functionalized electrodes; achieving high-quality van der Waals contact between a large-area, uniform two-dimensional material layer and a metal electrode; and improving the performance uniformity, yield, and long-term stability of two-dimensional material photodetector devices.

[0008] This invention provides a method for fabricating a two-dimensional material photodetector, comprising the following steps:

[0009] Two-dimensional materials are transferred onto a substrate containing a gate, source, and drain using a wet transfer method. Then, ozone generated by ultraviolet light is used to perform a first patterning process on the two-dimensional materials, resulting in a substrate containing a patterned two-dimensional material layer. Next, a poly(3-hexylthiophene) P3HT / [6,6]-phenyl-C61-butyrate methyl PCBM layer is spin-coated. Then, ozone generated by ultraviolet light is used to perform a second patterning process on the P3HT / PCBM layer, thus obtaining a two-dimensional material photodetector.

[0010] This invention utilizes ultraviolet light excitation to convert oxygen (O2) into ozone molecules (O3), which then further decompose to form a localized high-concentration reactive oxygen species atmosphere. These reactive oxygen atoms, due to their strong oxidizing properties, can uniformly oxidize and etch two-dimensional materials, enabling selective material removal. This patterning method is a relatively mild etching process, and the reaction process can be controlled by the etching time. Therefore, this invention can pattern two layers of material separately using a two-stage alignment process, allowing for controlled etching of the second layer without affecting the first layer, thereby enabling the mass production of two-dimensional material photodetectors.

[0011] Preferably, the method for fabricating the substrate comprising a gate, a source, and a drain includes the following steps:

[0012] Take a silicon wafer with a thermal oxide layer, use silicon as the back gate and the thermal oxide layer as the gate dielectric, use photoresist to etch and expose the source, drain and gate regions on the surface of the silicon wafer, deposit metal in the source, drain and gate regions by evaporation or sputtering process, and then remove the photoresist to obtain the substrate containing the gate, source and drain.

[0013] This invention combines photolithography with metal deposition / stripping techniques to achieve precise patterning, high-performance insulation, and low-resistance contact of the core electrodes (gate, source, and drain) of MOS devices. This method is the cornerstone of the modern semiconductor industry, possessing core advantages such as high precision, superior performance, good controllability, and strong scalability, laying a reliable foundation for the manufacture of various integrated circuit components.

[0014] Preferably, the wet transfer includes the following steps:

[0015] A polymer film is coated onto a metal foil on which two-dimensional materials are grown. The metal foil is then etched using an etching solution and cleaned to obtain a polymer / two-dimensional material film. The polymer / two-dimensional material film is then floated in water. A substrate containing a gate, source, and drain electrode is transferred directly below the film, and the polymer / two-dimensional material film is then retrieved, thus completing the wet transfer of the two-dimensional material.

[0016] Preferably, the corrosion solution is a mixture of copper sulfate, hydrochloric acid, and water in a ratio of 1g:1-10mL:1-10mL.

[0017] Preferably, the two-dimensional material is MoS2 or graphene.

[0018] In existing technologies, ferric chloride solution is often used as a corrosive agent. During and after the reaction, the Fe in the solution... 3+ and Fe 2+ Inevitably, these metal ions will adsorb onto the surface of the two-dimensional material (graphene) and the polymer (polymethyl methacrylate) serving as the transfer support layer. These metal ions are strong charge scattering centers, significantly reducing the carrier mobility of graphene and drastically deteriorating its electrical properties. Even repeated washing with large amounts of deionized water is unlikely to completely remove these strongly adsorbed ions. The main ion in the copper sulfate etching solution provided by this invention is Cu. 2+ Cl - H + and SO4 2- These ions, especially Cu 2+ The adsorption capacity on the graphene surface is much weaker than that of Fe. 3+ Therefore, the transferred graphene surface is very clean with few charge impurities, resulting in extremely high carrier mobility and excellent electrical properties. The slow reaction rate also avoids mechanical impact on the graphene.

[0019] Preferably, the dominant wavelength of the ultraviolet light is 254 nm.

[0020] Preferably, the first patterning process and the second patterning process specifically involve: aligning and loading a quartz mask or ordinary mask with a metal pattern layer onto a substrate to obtain a substrate-mask assembly; and using ultraviolet light to excite oxygen to generate ozone to etch the substrate-mask assembly, thereby completing the patterning.

[0021] Preferably, the temperature for the first patterning process and the second patterning process are both 25-80℃, and the time is both 90-150min.

[0022] Preferably, the exhaust system is activated simultaneously with the first and second patterning processes, and the exhaust system has a wind speed of 20-30 m / s. 3 / h.

[0023] Preferably, the spin-coating of the P3HT / PCBM layer includes the following steps:

[0024] Spin-coating a mixed solution of P3HT and PCBM onto a patterned two-dimensional material layer, spreading the mixed solution and then spinning it evenly, thus completing the spin-coating of the P3HT / PCBM layer.

[0025] Furthermore, the mixed solution is spread out at a low speed, with a rotation speed of 500-1000 rpm and a time of 10-20 seconds.

[0026] Furthermore, high-speed spinning is employed, with a rotation speed of 3000-4000 rpm and a time of 30-60 seconds.

[0027] This invention fabricates a P3HT:PCBM active layer film with complete coverage, uniform thickness, and ideal nanostructure on a patterned two-dimensional material layer. This aims to maximize the light absorption, exciton separation, and charge transport capabilities of the active layer, and to form excellent ohmic contact with the underlying electrode, ultimately achieving a balance between high energy conversion efficiency and highly reproducible fabrication process in organic solar cells.

[0028] The present invention also provides a method for preparing a two-dimensional material photodetector.

[0029] Furthermore, the two-dimensional material photodetector includes a metal layer (10-50 nm thick), a patterned two-dimensional material layer (single layer), and a patterned P3HT / PCBM layer (80-200 nm thick) sequentially disposed on a substrate.

[0030] This invention also provides the application of two-dimensional material photodetectors in the field of optoelectronics.

[0031] Beneficial effects

[0032] This invention is based on a dry etching process excited by ultraviolet light. It uses a gentle etching technique to pattern two-dimensional materials. The method provided can avoid the chemical doping and physical damage to the surface of two-dimensional materials caused by complex photoresist processes, reduce the complexity and cost of integrating high-quality two-dimensional materials with functionalized electrodes, and achieve high-quality van der Waals contact between large-area, uniform two-dimensional material layers and metal electrodes, thereby improving the performance uniformity, yield and long-term stability of two-dimensional material photodetectors. Attached Figure Description

[0033] Figure 1 This is a flowchart of the manufacturing process of a two-dimensional material photodetector in Example 1.

[0034] Figure 2 The patterned graphene layer obtained in step (3) of Example 1.

[0035] Figure 3 The patterned graphene layer and the patterned P3HT / PCBM layer obtained in step (4) of Example 1.

[0036] Figure 4 The image shows the IDS-VDS characteristic curve of the photodetector obtained in Example 1.

[0037] Figure 5 The image shows the It response curve of the photodetector obtained in Example 1. Detailed Implementation

[0038] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0039] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0040] Unless otherwise specified, all raw materials used in the embodiments of this invention were purchased through commercial channels;

[0041] Among them, the oxide layer of the silicon wafer with thermal oxide layer (SiO2 / Si) is greater than 285 nm, and the silicon is low-resistivity silicon with a resistivity range of approximately 0.0001 Ω·cm to 0.1 Ω·cm;

[0042] The mask or quartz mask consists of a light-transmitting quartz region and an opaque metal layer pattern region, with trenches in the metal layer pattern region ranging from 50 to 200 nm.

[0043] Unless otherwise specified, room temperature or normal temperature in the embodiments of the present invention refers to 25±3℃.

[0044] Example 1

[0045] This embodiment provides a method for fabricating a two-dimensional material photodetector, such as... Figure 1 As shown, it includes the following steps:

[0046] (1) Fabrication of the gate, source and drain of the photodetector

[0047] A silicon wafer (SiO2 / Si) with a thermal oxide layer is taken, using silicon itself as the back gate and the thermal oxide layer as the gate dielectric. A standard RCA cleaning process is used to thoroughly remove organic matter, metal ions, and particulate contaminants from the silicon wafer surface, ensuring initial surface cleanliness. A 1.7 μm layer of photoresist is then spin-coated onto the silicon wafer surface. The spin-coated wafer is placed on a hot plate and baked at 110°C for 90 seconds. After exposure and development, the unprotected silicon oxide is etched away with hydrofluoric acid (6 min), opening the area where the gate needs to be formed. The photoresist is removed, and the process is repeated with photolithography, exposure, and development to expose the source, drain, and gate regions. Metal (Cr 5 nm / Au 80 nm) is then deposited using evaporation or sputtering. The sample is immersed in solvents such as acetone overnight to dissolve the photoresist and simultaneously "lift" the metal layer from the photoresist, leaving only the two ends of the channel, forming the source, drain, and gate electrodes, thus obtaining a substrate containing the gate, source, and drain electrodes.

[0048] (2) Cut the copper foil with graphene grown on it to a suitable size and fix the copper foil (graphene side facing up) on the carrier of the spin coater. Add 30 μL of PMMA solution, first spread the adhesive at low speed (600 rpm, 6s), then spin it at high speed (preferably 4000 rpm, 30s) to mix it. Place the PMMA-coated sample on a hot plate and bake it at 90℃ for 10 min to cure the PMMA film. Prepare a fresh copper etching solution (copper sulfate: hydrochloric acid: water = 1g: 5mL: 5mL) and pour it into a clean petri dish. Use tweezers to slowly and tilt the PMMA / graphene / copper foil sample into the etching solution (copper sulfate etching solution), ensuring that the PMMA side is facing up. Let it stand for etching. After the copper foil is completely etched, the PMMA / graphene film will float on the surface of the liquid. Pick up the floating PMMA / graphene film to obtain the PMMA / graphene film.

[0049] (3) Transfer the PMMA / graphene film to a petri dish filled with deionized water, with the PMMA side facing up. Let the film float on the water surface and shake the basin to clean it for 2 minutes. Repeat the steps, transferring the film to the second and third deionized water dishes in turn to completely remove residual etchant. Then, immerse the substrate obtained in step (1) underwater, move it directly below the film, and then lift it up smoothly. After air drying, soak it in acetone for 2 hours to remove PMMA. Load it with a quartz mask (adhere the metal layer of the quartz mask to the two-dimensional material layer on the substrate and achieve micron-level alignment accuracy for loading) to obtain the substrate-mask assembly. Place it smoothly into the sample chamber of the ultraviolet ozone etching device, close the chamber door to ensure sealing, turn on the substrate heating device, set the temperature to 50°C, turn on the ultraviolet light source (main wavelength of 254 nm) for irradiation, and at the same time turn on the exhaust system (wind speed set to 20 m). 3 The reaction time was set to 90 minutes. During this process, oxygen free radicals generated by ultraviolet light excitation diffuse to the graphene surface, oxidizing them into gaseous products such as CO / CO2, which are then discharged with the gas flow. The graphene in the masked areas of the metal patterned layer is retained. Finally, rapid thermal annealing at 400℃ under vacuum for 1 hour is performed to form good ohmic or Schottky contacts between the metal electrode and the channel material, reducing contact resistance and obtaining a substrate containing a patterned graphene layer, such as... Figure 2 As shown.

[0050] (4) Weigh P3HT and PCBM powder and mix them in a chlorobenzene solution at a mass ratio of 1:1. Then spin-coat the mixture onto the patterned graphene layer (first layer material) obtained in step (3). Spread the adhesive at a low speed (600 rpm, 6s) and then spin it at a high speed (4000 rpm, 30s). Then, align and load the second quartz mask with the substrate using an alignment device (adhere the metal layer of the quartz mask to the P3HT / PCBM thin film layer on the substrate and achieve micron-level alignment accuracy). Pattern the P3HT / PCBM thin film using the same etching process as in step (3), where the etching temperature is 30℃ and the time is 2h. The patterned P3HT / PCBM thin film is obtained, as shown below. Figure 3 As shown.

[0051] (5) Wire bonding: Gold wires are soldered to the pressure points of the source, drain, and gate to connect to the external test circuit, thus obtaining the photodetector device.

[0052] Example 2

[0053] This embodiment provides a method for fabricating a two-dimensional material photodetector, such as... Figure 1 As shown, it includes the following steps:

[0054] (1) Fabrication of the gate, source and drain of the photodetector

[0055] A silicon wafer (SiO2 / Si) with a thermal oxide layer is taken, using silicon itself as the back gate and the thermal oxide layer as the gate dielectric. A standard RCA cleaning process is used to thoroughly remove organic matter, metal ions, and particulate contaminants from the silicon wafer surface, ensuring initial surface cleanliness. A 1.4 μm layer of photoresist is then spin-coated onto the silicon wafer surface. The spin-coated wafer is placed on a hot plate and baked at 90°C for 60 seconds. After exposure and development, the unprotected silicon oxide layer is etched away with hydrofluoric acid (4 min), opening the area where the gate needs to be formed. The photoresist is removed, and the process is repeated with photolithography, exposure, and development to expose the source, drain, and gate regions. Metal (Cr 3 nm / Au 30 nm) is then deposited using evaporation or sputtering. The sample is immersed in a solvent such as acetone overnight to dissolve the photoresist and simultaneously "lift" the metal layer from the photoresist, leaving only the two ends of the channel, forming the source, drain, and gate electrodes, thus obtaining a substrate containing the gate, source, and drain electrodes.

[0056] (2) Cut the copper foil with graphene grown on it to a suitable size and fix the copper foil (graphene side facing up) on the carrier of the spin coater. Add 50 μL of PMMA solution, first spread the adhesive at low speed (500 rpm, 20s), then spin it at high speed (3000 rpm, 50s) to mix it. Place the PMMA-coated sample on a hot plate and bake it at 80℃ for 10min to cure the PMMA film. Prepare a fresh copper etching solution (copper sulfate: hydrochloric acid: water = 1g: 5mL: 5mL) and pour it into a clean petri dish. Use tweezers to slowly and tilt the PMMA / graphene / copper foil sample into the etching solution (copper sulfate etching solution), ensuring that the PMMA side is facing up. Let it stand for etching. After the copper foil is completely etched, the PMMA / graphene film will float on the surface of the liquid. Pick up the floating PMMA / graphene film to obtain the PMMA / graphene film.

[0057] (3) Transfer the PMMA / graphene film to a petri dish filled with deionized water, with the PMMA side facing up. Let the film float on the water surface and shake the basin to clean it for 2 minutes. Repeat the steps, transferring the film to the second and third deionized water dishes in turn to completely remove residual etchant. Then, immerse the substrate obtained in step (1) underwater, move it directly below the film, and then lift it up smoothly. After air drying, soak it in acetone for 2 hours to remove PMMA. Load it with a quartz mask (adhere the metal layer of the quartz mask to the two-dimensional material layer on the substrate and achieve micron-level alignment accuracy for loading) to obtain the substrate-mask assembly. Place it smoothly into the sample chamber of the ultraviolet ozone etching device, close the chamber door to ensure sealing, turn on the substrate heating device, set the temperature to 50°C, turn on the ultraviolet light source (main wavelength of 254 nm) for irradiation, and at the same time turn on the exhaust system (wind speed set to 20 m). 3The reaction time was set to 90 minutes. During this process, oxygen free radicals generated by ultraviolet light excitation diffuse to the graphene surface, oxidize them into gaseous products such as CO / CO2, and are discharged with the gas flow. The graphene in the masked area of ​​the metal patterned layer is retained. Finally, it is rapidly thermally annealed at 400℃ under vacuum for 1 hour to form a good ohmic or Schottky contact between the metal electrode and the channel material, reduce the contact resistance, and obtain a substrate containing a patterned graphene layer.

[0058] (4) Weigh P3HT and PCBM powder and mix them in a chlorobenzene solution at a mass ratio of 1:1. Then spin-coat the mixture onto the patterned graphene layer (first layer material) obtained in step (3). Spread the adhesive at a low speed (500 rpm, 20s) and then spin it at a high speed (4000 rpm, 60s). Then, align and load the second quartz mask with the substrate using an alignment device (adhere the metal layer of the quartz mask to the P3HT / PCBM thin film layer on the substrate and achieve micron-level alignment accuracy). Pattern the P3HT / PCBM thin film using the same etching process as in step (3), where the etching temperature is 30℃ and the time is 2h. The patterned P3HT / PCBM thin film is obtained.

[0059] (5) Wire bonding: Gold wires are soldered to the pressure points of the source, drain, and gate to connect to the external test circuit, thus obtaining the photodetector device.

[0060] Example 3

[0061] This embodiment provides a method for fabricating a two-dimensional material photodetector, such as... Figure 1 As shown, it includes the following steps:

[0062] (1) Fabrication of the gate, source and drain of the photodetector

[0063] Take a silicon wafer (SiO2 / Si) with a thermal oxide layer, using silicon itself as the back gate and the thermal oxide layer as the gate dielectric. A standard RCA cleaning process is used to thoroughly remove organic matter, metal ions, and particulate contaminants from the silicon wafer surface, ensuring initial surface cleanliness. Then, a 3μm layer of photoresist is spin-coated onto the silicon wafer surface. The spin-coated wafer is placed on a hot plate and baked at 110°C for 80 seconds. Next, through exposure and development, hydrofluoric acid is used to etch away the unprotected silicon oxide from the photoresist (8 minutes), opening the area where the gate needs to be formed. The photoresist is removed, and the process is repeated with photolithography, exposure, and development to expose the source, drain, and gate regions. Then, metal (Cr 10 nm / Au 100 nm) is deposited using evaporation or sputtering. The sample is immersed in solvents such as acetone overnight to dissolve the photoresist and simultaneously "lift" the metal layer from the photoresist, leaving only the two ends of the channel, forming the source, drain, and gate electrodes, thus obtaining a substrate containing the gate, source, and drain electrodes.

[0064] (2) Cut the copper foil with graphene grown on it to a suitable size and fix the copper foil (graphene side facing up) on the carrier of the spin coater. Add 100 μL of PMMA solution, first spread the adhesive at low speed (1000 rpm, 10s), then spin it at high speed (3000 rpm, 60s) to mix it. Place the PMMA-coated sample on a hot plate and bake it at 180℃ for 10min to cure the PMMA film. Prepare a fresh copper etching solution (copper sulfate: hydrochloric acid: water = 1g: 5mL: 5mL) and pour it into a clean petri dish. Use tweezers to slowly and tilt the PMMA / graphene / copper foil sample into the etching solution (copper sulfate etching solution), ensuring that the PMMA side is facing up. Let it stand for etching. After the copper foil is completely etched, the PMMA / graphene film will float on the surface of the liquid. Pick up the floating PMMA / graphene film to obtain the PMMA / graphene film.

[0065] (3) Transfer the PMMA / graphene film to a petri dish filled with deionized water, with the PMMA side facing up. Let the film float on the water surface and shake the basin to clean it for 2 minutes. Repeat the steps, transferring the film to the second and third deionized water dishes in turn to completely remove residual etchant. Then, immerse the substrate obtained in step (1) underwater, move it directly below the film, and then lift it up smoothly. After air drying, soak it in acetone for 2 hours to remove PMMA. Load it with a quartz mask (adhere the metal layer of the quartz mask to the two-dimensional material layer on the substrate and achieve micron-level alignment accuracy for loading) to obtain the substrate-mask assembly. Place it smoothly into the sample chamber of the ultraviolet ozone etching device, close the chamber door to ensure sealing, turn on the substrate heating device, set the temperature to 50°C, turn on the ultraviolet light source (main wavelength of 254 nm) for irradiation, and at the same time turn on the exhaust system (wind speed set to 20 m). 3 The reaction time was set to 90 minutes. During this process, oxygen free radicals generated by ultraviolet light excitation diffuse to the graphene surface, oxidize them into gaseous products such as CO / CO2, and are discharged with the gas flow. The graphene in the masked area of ​​the metal patterned layer is retained. Finally, it is rapidly thermally annealed at 400℃ under vacuum for 1 hour to form a good ohmic or Schottky contact between the metal electrode and the channel material, reduce the contact resistance, and obtain a substrate containing a patterned graphene layer.

[0066] (4) Weigh P3HT and PCBM powder and mix them in a chlorobenzene solution at a mass ratio of 1:1. Then spin-coat the mixture onto the patterned graphene layer (first layer material) obtained in step (3). Spread the adhesive at a low speed (1000 rpm, 10s) and then spin-coat it at a high speed (4000 rpm, 60s). Then, align and load the second quartz mask with the substrate using an alignment device (adhere the metal layer of the quartz mask to the P3HT / PCBM thin film layer on the substrate and achieve micron-level alignment accuracy). Pattern the P3HT / PCBM thin film using the same etching process as in step (3), where the etching temperature is 30℃ and the time is 2h. The patterned P3HT / PCBM thin film is obtained.

[0067] (5) Wire bonding: Gold wires are soldered to the pressure points of the source, drain, and gate to connect to the external test circuit, thus obtaining the photodetector device.

[0068] The chip obtained in Example 1 was packaged or its electrical performance was tested directly on a probe station using a semiconductor parameter analyzer. The results are as follows: Figure 4-5 As shown, Figure 4 The IDS-VDS characteristic curve of the photodetector device obtained in Example 1; Figure 5 The image shows the It response curve of the photodetector obtained in Example 1.

[0069] It can be seen that, under the same VDS, the difference between the current under illumination and the current under darkness (photocurrent) is large, indicating that the detector has a strong response to light signals and high sensitivity; in addition, the It response curve shows that the device has a fast response speed and good repeatability in multiple cycles.

[0070] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for fabricating a two-dimensional material photodetector, characterized in that, Includes the following steps: Two-dimensional materials are transferred onto a substrate containing a gate, source, and drain using a wet transfer method. Then, ozone generated by ultraviolet light is used to perform a first patterning process on the two-dimensional materials, resulting in a substrate containing a patterned two-dimensional material layer. Next, a poly(3-hexylthiophene) P3HT / [6,6]-phenyl-C61-butyrate methyl PCBM layer is spin-coated. Then, ozone generated by ultraviolet light is used to perform a second patterning process on the P3HT / PCBM layer, thus obtaining a two-dimensional material photodetector.

2. The preparation method according to claim 1, characterized in that, The method for fabricating the substrate comprising a gate, a source, and a drain includes the following steps: Take a silicon wafer with a thermal oxide layer, use silicon as the back gate and the thermal oxide layer as the gate dielectric, use photoresist to etch and expose the source, drain and gate regions on the surface of the silicon wafer, deposit metal in the source, drain and gate regions by evaporation or sputtering process, and then remove the photoresist to obtain the substrate containing the gate, source and drain.

3. The preparation method according to claim 1, characterized in that, The wet transfer process includes the following steps: A polymer film is coated onto a metal foil on which two-dimensional materials are grown. The metal foil is then etched using an etching solution and cleaned to obtain a polymer / two-dimensional material film. The polymer / two-dimensional material film is then floated in water. A substrate containing a gate, source, and drain electrode is transferred directly below the film, and the polymer / two-dimensional material film is then retrieved, thus completing the wet transfer of the two-dimensional material.

4. The preparation method according to claim 3, characterized in that, The corrosion solution is a mixture of copper sulfate, hydrochloric acid, and water in a ratio of 1g:1-10mL:1-10mL.

5. The preparation method according to claim 1, characterized in that, The dominant wavelength of the ultraviolet light is 254 nm.

6. The preparation method according to claim 1, characterized in that, The temperature for both the first and second patterning processes is 25-80℃, and the time is 90-150 min.

7. The preparation method according to claim 1 or 6, characterized in that, The exhaust system is activated simultaneously during the first and second patterning processes, and the exhaust system has a wind speed of 20-30 m / s. 3 / h.

8. The preparation method according to claim 1, characterized in that, The spin-coating of the P3HT / PCBM layer includes the following steps: Spin-coating a mixed solution of P3HT and PCBM onto a patterned two-dimensional material layer, spreading the mixed solution and then spinning it evenly, thus completing the spin-coating of the P3HT / PCBM layer.

9. A two-dimensional material photodetector obtained by a preparation method according to any one of claims 1 to 8.

10. The application of the two-dimensional material photodetector as described in claim 9 in the field of optoelectronics.

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