Self-driven photoelectric detector based on ZnIn2S4 nanosheet / Si heterojunction and preparation method thereof

Abstract

The invention belongs to the technical field of optical detection, and particularly relates to a self-driven photoelectric detector which sequentially comprises a metal In point electrode, a metal Pd front electrode, a ZnIn2S4 nanosheet film layer prepared through PdSe2 modification, a Si single crystal substrate and a metal In back electrode from top to bottom. The ZnIn2S4 nanosheet thin film layer prepared through modification of PdSe2 is prepared through magnetron sputtering, chemical vapor deposition and other methods. Test results show that the prepared thin film device shows good self-driven light detection performance under ultraviolet to mid-infrared light illumination, and has the advantages of stable performance and the like.

Description

Technical Field

[0001] This invention belongs to the field of optical detection technology, specifically relating to a mid-infrared self-driven photodetector and its preparation method. Background Technology

[0002] For nearly half a century, the rapid development of optoelectronic technology has profoundly reshaped the modern technological landscape and permeated all aspects of daily human activities. Photodetectors are core components of the optoelectronic industry, responsible for converting detected optical signals into electrical signals. They not only bridge the gap between light and electricity, the two major information carriers, but also directly affect the detection sensitivity, response speed, and operational reliability of the entire optoelectronic system. In the process of modern information technology transitioning from classical to quantum computing, photodetectors continue to play an irreplaceable fundamental supporting role. As the core unit of optoelectronic systems, these devices demonstrate key technological effectiveness in multiple fields, including fiber optic communication, space exploration, night vision, biomedical detection, and instrument analysis.

[0003] Based on wavelength, sunlight can be divided into ultraviolet (10-400 nm), visible (400-760 nm), and infrared (760 nm-1 mm). Photodetectors are also classified according to their corresponding operating wavelengths: ultraviolet photodetectors, visible photodetectors, and infrared photodetectors. With the rapid development of broadband detection fields such as multispectral remote sensing, broadband analysis, environmental monitoring, biomedical detection, and free-space optical communication, the development of ultraviolet-infrared (UV-IR) broadband detectors is becoming increasingly important. These applications place demands on detector performance such as broadband response, high sensitivity, fast response speed, and low noise. However, traditional UV-IR broadband detection is often achieved by combining multiple discrete narrowband detectors of different wavelengths. The detection module system is complex and bulky, failing to meet the growing application demands for miniaturized, highly integrated broadband detectors in the photodetector field. To date, research on UV-IR broadband high-sensitivity photodetectors remains limited. Therefore, how to design device structures and select specific semiconductor materials to achieve high-efficiency broadband detection has become an urgent problem to be solved.

[0004] In addition, the rapid development of nanoscience has also brought new development opportunities to photodetectors. When the material scale reaches the nanoscale (i.e., 1-100 nm), many physical and chemical properties that are not found in macroscopic and microscopic materials will appear. According to the number of dimensions of the material at the nanoscale, nanomaterials can be divided into three categories: (1) zero-dimensional (0D) nanomaterials, that is, all three dimensions of the material are at the nanoscale, such as quantum dots and nanoparticles; (2) one-dimensional (1D) nanomaterials, that is, two of the three dimensions of the material are at the nanoscale, such as nanorods, nanowires and nanotubes; (3) two-dimensional (2D) nanomaterials, that is, only one of the three dimensions of the material is at the nanoscale, such as nanofilms. Among them, two-dimensional materials, due to their ultrathin structure, unique physical properties and strong light-matter interaction, provide new possibilities for the development of photodetectors.

[0005] As a typical visible-light-responsive n-type two-dimensional ternary sulfide, ZnIn₂S₄ possesses excellent photochemical stability and a tunable direct bandgap (1.72-2.85 eV), making it widely used in thin-film solar cells and photocatalysis. Therefore, exploring how to prepare two-dimensional ZnIn₂S₄ films is a primary problem we need to solve. Research revealed that ZnIn₂S₄ exposed to a strongly reducing environment breaks the Zn-S bond, generating a large number of poorly coordinated S atoms on its surface. These undercoordinated zinc or sulfur vacancies can combine with other active molecules or ions to form dense heterojunctions through chemical bonds. To this end, we used the transition metal chalcogenide PdSe₂ as a transition layer to construct a hybrid-dimensional heterojunction, significantly improving the device performance and broadening its light absorption range to the mid-infrared. A ZnIn₂S₄-based broadband photodetector was successfully constructed. Summary of the Invention

[0006] The purpose of this invention is to provide a broadband self-driven photodetector based on ZnIn2S4 nanosheets / Si heterojunction and its fabrication method, which can solve the problem of the generally poor performance of current broadband self-driven photodetectors.

[0007] The technical problem to be solved by the present invention to achieve the above objectives is to improve the performance of photodetectors by methods such as magnetron sputtering and chemical vapor deposition; that is, to prepare a PdSe2-modified ZnIn2S4 nanosheet thin film layer on the surface of a silicon substrate by magnetron sputtering and chemical vapor deposition to obtain a broadband self-driven photodetector with excellent performance.

[0008] The technical solution adopted by this invention to achieve the above-mentioned objective is a broadband self-driven photodetector based on a ZnIn2S4 nanosheet / Si heterojunction, characterized in that it has a layered structure, comprising, from top to bottom, a metal In point electrode, a metal Pd front electrode, a PdSe2-modified Sb2O3 nanorod thin film layer, a Si single-crystal substrate, and a metal In back electrode; wherein:

[0009] Preferably, the Si single crystal substrate is single-sided polished, with a crystal orientation of (100) plane, a conductivity type of p-type, and a resistivity of 0.1 to 1 ohm·cm;

[0010] A method for fabricating a broadband self-driven photodetector based on ZnIn2S4 nanosheets / Si heterojunction includes the following steps:

[0011] (1) Select a Si substrate and clean it;

[0012] (2) Dry the Si substrate after cleaning;

[0013] (3) The dried Si substrate is placed in a vacuum chamber and a Pd thin film is deposited on the surface of the Si substrate by radio frequency magnetron sputtering technology under an argon atmosphere, using ionized argon ions to bombard the Pd target. The target purity is 99.9%, the argon pressure is maintained at 1.2 Pascals, the target-substrate distance is 50 mm, the film deposition temperature is 20-25 degrees Celsius, and the film thickness is 10-20 nanometers.

[0014] (4) Place the Si substrate covered with a Pd thin film layer into the CVD back end, add Se powder to the front end, evaporation temperature is 300℃, reaction temperature at the back end is 300℃, gas is introduced, the temperature rise rate is 10℃ per minute, and the temperature is maintained at 300℃ for 90 minutes, and then naturally cooled to room temperature; a PdSe2 substrate is obtained on Si.

[0015] (5) ZnIn2S4 nanosheets were grown on the PdSe2 seed layer by hydrothermal method: 15 ml of anhydrous ethanol solution was taken and 35 ml of deionized water was added as solvent. 430 mg of zinc acetate, 480 mg of thioacetamide and 350 mg of indium trichloride were added to the solvent and stirred with a magnetic stirrer for 30 min to obtain a transparent dispersion. The dispersion was transferred to a high-temperature reactor and the Si substrate with the PdSe2 seed layer obtained in step (4) was suspended in the dispersion with high-temperature resistant tape, with the PdSe2 seed layer facing down. The reaction was carried out at 180 °C for 30 min. After the reaction was completed, the substrate was taken out and its surface was rinsed with deionized water. It was then placed in a 60 °C drying oven and dried overnight to obtain ZnIn2S4 nanosheets on the PdSe2 seed layer.

[0016] (6) Take out the sample obtained in step (5) and cover the surface of the ZnIn2S4 nanosheet thin film layer grown on the PdSe2 surface with a mask, and then put the sample into a vacuum chamber; use DC magnetron sputtering technology to bombard the metal Pd target with ionized argon ions to deposit the metal Pd front electrode on the surface of the ZnIn2S4 nanosheet thin film layer grown on the PdSe2 surface; the Pd target is a Pd metal target with a purity of 99.9%; the argon gas pressure is maintained at 5.0 Pascals, the target-substrate distance is 50 mm, the deposition temperature of the metal Pd thin film is 20-25 degrees Celsius, and the thickness of the metal Pd front electrode is 5-15 nanometers;

[0017] (7) Press the metal In electrode on the metal Pd front electrode and the Si substrate respectively, and lead out the metal Cu wire to complete the device fabrication.

[0018] Preferably, in step (1), the Si substrate is a p-type Si single crystal substrate with a size of 10 mm × 10 mm and a resistivity of 0.1 to 1 ohm·cm; the cleaning process is as follows: the Si substrate is ultrasonically cleaned multiple times in high-purity alcohol and acetone solutions, with each cleaning time lasting 180 seconds.

[0019] Preferably, in step (3), the back vacuum level of the vacuum chamber is 5×10⁻⁶. -5 Pascal, the vacuum condition is achieved by a two-stage vacuum pump consisting of a mechanical pump and a molecular pump.

[0020] Preferably, in step (4), the gas ratio and flow rate are argon: 50 sccm.

[0021] Preferably, in step (5), the hydrothermal reaction temperature is 180°C and the time is 30 min.

[0022] Preferably, in step (6), the mask material is stainless steel, with a thickness of 0.1 mm, a size of 12 mm × 12 mm, and an aperture size of 5 mm × 5 mm; the back vacuum degree of the vacuum chamber is 5 × 10⁻⁶. -5 Pascal, the vacuum condition is achieved by a two-stage vacuum pump consisting of a mechanical pump and a molecular pump.

[0023] Preferably, in step (7), the metal electrode and the wire material are In and Cu, respectively, wherein the purity of In is 99.5%, the size and thickness of the metal In electrode on the metal Pd thin film layer are 1 mm × 1.5 mm and 1 mm, respectively, the size and thickness of the metal In electrode on the Si substrate are 10 mm × 10 mm and 2 mm, respectively, and the diameter of the Cu wire is 0.1 mm.

[0024] The aforementioned devices with self-driven photodetector capabilities can be applied in the fabrication of self-driven photodetectors.

[0025] The beneficial technical effects of this invention are:

[0026] This invention fabricates a ZnIn2S4 nanosheet thin film layer on a Si substrate by modifying it with PdSe2, thus developing a thin-film device with self-driven photodetector capability. Test results show that the fabricated thin-film device exhibits significant sensitivity to ultraviolet-mid-infrared light; specifically, at a working voltage of 0 volts, the device current increases significantly under illumination. The light response of the fabricated thin-film device increases with increasing light intensity. Furthermore, the device demonstrates good periodic repeatability. Compared with existing self-driven photodetectors, the fabrication method of the device involved in this invention is simple, non-toxic, and low-cost, and possesses significant advantages in photoresponse performance, making it widely applicable in the field of photodetectors. Attached Figure Description

[0027] Figure 1 The image shows the XRD characterization pattern of the fabricated device.

[0028] Figure 2 A schematic diagram of the structure used to measure the photodetector performance of the fabricated device.

[0029] Figure 3 This represents the device's response performance to light of different wavelengths and power densities when the applied voltage is 0 volts.

[0030] Figure 4 This is a SEM image of the PdSe2 seed layer.

[0031] Figure 5 The image shows the SEM characterization of ZnIn2S4 nanosheets. Detailed Implementation

[0032] This invention utilizes magnetron sputtering and chemical vapor deposition to prepare ZnIn2S4 nanosheet thin films on a Si semiconductor substrate by modifying it with PdSe2. A Pd metal front electrode is deposited using DC magnetron sputtering, and an In metal electrode and connecting metal wires are then pressed to form the device. When exposed to light, due to the photoelectric effect and the presence of a built-in electric field, the device exhibits significant response performance to deep ultraviolet light at an applied voltage of 0 volts.

[0033] The present invention will now be described in detail with reference to the embodiments and accompanying drawings.

[0034] This invention relates to a broadband self-driven photodetector based on a ZnIn2S4 nanosheet / Si heterojunction, comprising a ZnIn2S4 nanosheet thin film layer prepared by PdSe2 modification and a Si semiconductor substrate. The Si substrate serves as a carrier for PdSe2, and the ZnIn2S4 nanosheet thin film layer prepared by PdSe2 modification is disposed on the surface of the Si substrate. The Si substrate is a p-type Si single crystal substrate with a resistivity of 0.1–1 ohm·cm and a (100) orientation.

[0035] Furthermore, a mask is placed over the surface of the ZnIn2S4 nanosheet thin film grown on the PdSe2 surface, and then the sample is placed in a vacuum chamber. DC magnetron sputtering is used to bombard the metal Pd target with ionized argon ions to deposit a metal Pd front electrode on the surface of the ZnIn2S4 nanosheet thin film grown on the PdSe2 surface. The Pd target is a Pd metal target with a purity of 99.9%. The argon gas pressure is maintained at a constant 5.0 Pascals, the target-substrate distance is 50 mm, the deposition temperature of the metal Pd thin film is 20–25 degrees Celsius, and the thickness of the metal Pd front electrode is 5–15 nanometers.

[0036] Furthermore, metal In electrodes are pressed onto the Pd front electrode and the Si substrate respectively, and wires are led out to obtain the device.

[0037] The fabrication method of the above-mentioned device specifically includes the following steps:

[0038] (1) Select a Si substrate and clean it;

[0039] (2) Dry the Si substrate after cleaning;

[0040] (3) The dried Si substrate is placed in a vacuum chamber and a Pd thin film is deposited on the surface of the Si substrate by radio frequency magnetron sputtering technology under an argon atmosphere, using ionized argon ions to bombard the Pd target. The target purity is 99.9%, the argon pressure is maintained at 1.2 Pascals, the target-substrate distance is 50 mm, the film deposition temperature is 20-25 degrees Celsius, and the film thickness is 10-20 nanometers.

[0041] (4) Place the Si substrate covered with a Pd thin film layer into the CVD back end, add Se powder to the front end, evaporation temperature is 300℃, reaction temperature at the back end is 300℃, gas is introduced, the temperature rise rate is 10℃ per minute, and the temperature is maintained at 300℃ for 90 minutes, and then naturally cooled to room temperature; a PdSe2 substrate is obtained on Si.

[0042] (5) ZnIn2S4 nanosheets were grown on the PdSe2 seed layer by hydrothermal method: 15 ml of anhydrous ethanol solution was taken and 35 ml of deionized water was added as solvent. 430 mg of zinc acetate, 480 mg of thioacetamide and 350 mg of indium trichloride were added to the solvent and stirred with a magnetic stirrer for 30 min to obtain a transparent dispersion. The dispersion was transferred to a high-temperature reactor and the Si substrate with the PdSe2 seed layer obtained in step (4) was suspended in the dispersion with high-temperature resistant tape, with the PdSe2 seed layer facing down. The reaction was carried out at 180 °C for 30 min. After the reaction was completed, the substrate was taken out and its surface was rinsed with deionized water. It was then placed in a 60 °C drying oven and dried overnight to obtain ZnIn2S4 nanosheets on the PdSe2 seed layer.

[0043] (6) Take out the sample obtained in step (5) and cover the surface of the ZnIn2S4 nanosheet thin film layer grown on the PdSe2 surface with a mask, and then put the sample into a vacuum chamber; use DC magnetron sputtering technology to bombard the metal Pd target with ionized argon ions to deposit the metal Pd front electrode on the surface of the ZnIn2S4 nanosheet thin film layer grown on the PdSe2 surface; the Pd target is a Pd metal target with a purity of 99.9%; the argon gas pressure is maintained at 5.0 Pascals, the target-substrate distance is 50 mm, the deposition temperature of the metal Pd thin film is 20-25 degrees Celsius, and the thickness of the metal Pd front electrode is 5-15 nanometers;

[0044] (7) Press the metal In electrode on the metal Pd front electrode and the Si substrate respectively, and lead out the metal Cu wire to complete the device fabrication.

[0045] The aforementioned devices with self-driven photodetector capabilities can be applied in the fabrication of self-driven photodetectors.

[0046] The effects of the present invention are further illustrated below with reference to performance measurement results:

[0047] Figure 1 The XRD pattern of the fabricated device is shown. The XRD pattern indicates that the ZnIn2S4 nanosheets exhibit good crystallinity.

[0048] Figure 2 A schematic diagram of the structure used to measure the photodetector performance of the fabricated device.

[0049] Figure 3The periodic response performance of the device to light under an applied voltage of 0 volts is shown in the figure. As the figure illustrates, by changing the illumination environment, the fabricated thin-film device exhibits good photoresponse performance and stability. At a test voltage of 0 volts, the thin-film device responds under illumination with wavelengths ranging from 365 nm to 4.65 μm (dynamic response curves at different optical powers). These characteristics further demonstrate that this thin-film device can be used to develop novel self-driven broadband photodetectors.

[0050] Figure 4 This is a SEM image of the PdSe2 seed layer. The SEM image shows that the PdSe2 seed layer successfully grew on the PdSe2 surface.

[0051] Figure 5 The image shows the SEM characterization of ZnIn2S4 nanosheets. The SEM images demonstrate that ZnIn2S4 nanosheets were successfully grown on the PdSe2 surface.

Claims

1. A mid-infrared self-driven photodetector based on ZnIn2S4 nanosheets / Si heterojunction, characterized in that: It includes a metal In point electrode, a metal Pd front electrode, a ZnIn2S4 nanosheet thin film layer grown on the PdSe2 surface, a Si single crystal substrate, and a metal In back electrode. The ZnIn2S4 nanosheet thin film layer grown on the PdSe2 surface is disposed on the Si substrate surface, the metal Pd front electrode is on the surface of the ZnIn2S4 nanosheet thin film layer grown on the PdSe2 surface, and the metal In electrode is pressed onto the metal Pd front electrode and the Si substrate surface, respectively.

2. The mid-infrared self-driven photodetector based on ZnIn2S4 nanosheets / Si heterojunction according to claim 1, characterized in that: The Si substrate is a p-type Si single crystal substrate with a resistivity of 0.1 to 1 ohm·cm, enabling mid-infrared self-driven detection.

3. A method for fabricating a mid-infrared self-driven photodetector based on ZnIn2S4 nanosheets / Si heterojunction, characterized in that... Includes the following steps: (1) Select a Si substrate and clean it; (2) Dry the Si substrate after cleaning; (3) The dried Si substrate is placed in a vacuum chamber and a Pd thin film is deposited on the surface of the Si substrate by radio frequency magnetron sputtering technology under an argon atmosphere, using ionized argon ions to bombard the Pd target. The target purity is 99.9%, the argon pressure is maintained at 1.2 Pascals, the target-substrate distance is 50 mm, the film deposition temperature is 20-25 degrees Celsius, and the film thickness is 10-20 nanometers. (4) Place the Si substrate covered with a Pd thin film layer into the CVD back end, add Se powder to the front end, evaporation temperature is 300℃, reaction temperature at the back end is 300℃, gas is introduced, the temperature rise rate is 10℃ per minute, and the temperature is maintained at 300℃ for 90 minutes, and then naturally cooled to room temperature; a PdSe2 substrate is obtained on Si. (5) ZnIn2S4 nanosheets were grown on the PdSe2 seed layer by hydrothermal method: 15 ml of anhydrous ethanol solution was taken and 35 ml of deionized water was added as solvent. 430 mg of zinc acetate, 480 mg of thioacetamide and 350 mg of indium trichloride were added to the solvent and stirred with a magnetic stirrer for 30 min to obtain a transparent dispersion. The dispersion was transferred to a high-temperature reactor and the Si substrate with the PdSe2 seed layer obtained in step (4) was suspended in the dispersion with high-temperature resistant tape, with the PdSe2 seed layer facing down. The reaction was carried out at 180 °C for 30 min. After the reaction was completed, the substrate was taken out and its surface was rinsed with deionized water. It was then placed in a 60 °C drying oven and dried overnight to obtain ZnIn2S4 nanosheets on the PdSe2 seed layer. (6) Take out the sample obtained in step (5) and cover the surface of the ZnIn2S4 nanosheet thin film layer grown on the PdSe2 surface with a mask, and then put the sample into a vacuum chamber; use DC magnetron sputtering technology to bombard the metal Pd target with ionized argon ions to deposit the metal Pd front electrode on the surface of the Sb2O3 nanorod thin film layer grown on the PdTe2 surface; the Pd target is a Pd metal target with a purity of 99.9%; the argon gas pressure is maintained at 5.0 Pascals, the target-substrate distance is 50 mm, the deposition temperature of the metal Pd thin film is 20-25 degrees Celsius, and the thickness of the metal Pd front electrode is 5-15 nanometers; (7) Press the metal In electrode on the metal Pd front electrode and the Si substrate respectively, and lead out the metal Cu wire to complete the device fabrication.

4. The method for fabricating a mid-infrared self-driven photodetector based on a ZnIn2S4 nanosheet / Si heterojunction according to claim 3, characterized in that: In step (1), the Si substrate is a p-type Si single crystal substrate with a size of 10 mm × 10 mm and a resistivity of 0.1 to 1 ohm·cm. The cleaning process is as follows: the Si substrate is ultrasonically cleaned multiple times in high-purity alcohol and acetone solutions, with each cleaning lasting 180 seconds.

5. The method for fabricating a mid-infrared self-driven photodetector based on a ZnIn2S4 nanosheet / Si heterojunction according to claim 3, characterized in that: In step (6), the mask sheet is made of stainless steel, with a thickness of 0.1 mm, a size of 12 mm × 12 mm, and a hole size of 5 mm × 5 mm.

6. The method for fabricating a mid-infrared self-driven photodetector based on a ZnIn2S4 nanosheet / Si heterojunction according to claim 3, characterized in that: In step (4), the gas ratio and flow rate are argon: 50 sccm.

7. The method for fabricating a mid-infrared self-driven photodetector based on a ZnIn2S4 nanosheet / Si heterojunction according to claim 3, characterized in that: In step (7), the purity of the raw material In used for the metal In electrode is 99.5%, the size and thickness of the metal In electrode on the metal Pd front electrode are 1 mm × 1.5 mm and 1 mm, respectively, the size and thickness of the metal In electrode on the Si substrate are 10 mm × 10 mm and 2 mm, respectively, and the diameter of the Cu wire is 0.1 mm.

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