Self-driven photoelectric detector based on Bi2S3 / Si heterojunction and preparation method thereof
By preparing large-area ordered Bi2S3 thin films on a mica substrate and transferring them to a Si substrate to construct a Bi2S3/Si heterojunction, the problem of poor quality of Bi2S3 photodetector thin films was solved, achieving high-performance and low-cost fabrication of self-driven photodetectors, which is suitable for the field of photoelectric detection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA UNIV OF PETROLEUM (EAST CHINA)
- Filing Date
- 2026-01-15
- Publication Date
- 2026-04-21
AI Technical Summary
The poor thin film quality of existing Bi2S3 photodetectors limits the detection performance of the devices, and most photodetectors require power supply, which hinders their practical application.
A large-area ordered Bi2S3 thin film was prepared on a mica substrate by chemical vapor deposition and then transferred to a Si substrate with surface energy assistance to construct a Bi2S3/Si heterojunction, forming a self-driven photodetector.
The prepared Bi2S3/Si heterojunction photodetector exhibits significant near-infrared light response performance under no external voltage conditions, with high responsivity and good stability, and the preparation method is simple and low cost.
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Figure CN121908655A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of optical detection technology, specifically relating to a near-infrared self-driven photodetector and its preparation method. Background Technology
[0002] A photodetector is an electronic device that converts light signals into electrical signals. Photodetectors have been widely used in fields such as biological imaging, non-destructive testing, communications, and environmental monitoring. However, most reported photodetectors require a power source, which severely hinders their practical application. Therefore, developing self-powered photodetectors is of great significance.
[0003] An ideal photodetector must meet core requirements such as high responsivity, excellent detectivity, good long-term stability, and low-cost fabrication. This necessitates the search for new types of photosensitive materials, which should possess advantages such as large specific surface area, high volumetric loading, short mass transport paths, and stronger light-trapping capabilities. Photosensitive materials are used to construct heterojunctions, and the quality of these heterojunctions determines the final performance of the photodetector. Currently, an increasing number of materials are being used in photodetection, including metal oxides, transition metal sulfides, topological insulators, graphene, lead sulfide quantum dots, perovskites, polymers, and covalent organic framework materials.
[0004] Nitrogen group sulfides are a class of compounds existing in the form of minerals, possessing low cost, abundant reserves, and interesting properties. Bismuth sulfide, a member of the nitrogen group sulfides, belongs to the orthorhombic crystal system and has a band gap of approximately 1.2 eV. Due to its high mobility, carrier lifetime, and high absorption coefficient, it holds great promise for applications in photoelectric detection. However, currently reported Bi₂S₃ photodetectors are all based on single nanowires or nanoribbons, and the grown Bi₂S₃ films are composed of disordered nanorods, resulting in poor film quality. This limits the detection performance of devices based on these Bi₂S₃ films. Compared to micron-scale nanowires, thin-film photodetectors with high area coverage and large specific surface area have become a current research hotspot. Therefore, exploring how to prepare structurally ordered Bi₂S₃ films with large specific surface area is a primary problem we need to solve. We successfully synthesized large-area ordered Bi₂S₃ films composed of one-dimensional units on mica sheets using chemical vapor deposition, optimizing the growth morphology of the Bi₂S₃ material, which can improve device performance. Meanwhile, a self-driven photodetector based on a Bi2S3 / Si heterojunction was successfully constructed using surface energy-assisted transfer. Summary of the Invention
[0005] The purpose of this invention is to provide a near-infrared self-driven photodetector based on a Bi2S3 / Si heterojunction and its fabrication method, which can solve the problem of the generally poor performance of current near-infrared self-driven photodetectors.
[0006] The technical problem to be solved by the present invention to achieve the above-mentioned objective is to improve the performance of photodetectors by means of chemical vapor deposition, surface energy-assisted transfer and other methods; that is, to prepare a Bi2S3 thin film on the surface of a mica substrate by chemical vapor deposition, and to construct a Bi2S3 / Si heterojunction by surface energy-assisted transfer of the Bi2S3 thin film to a silicon wafer, so as to obtain a near-infrared self-driven photodetector with excellent performance.
[0007] The technical solution adopted by this invention to achieve the above-mentioned objective is a near-infrared self-driven photodetector based on a Bi2S3 / 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, an ordered Bi2S3 thin film layer, a Si single-crystal substrate, and a metal In back electrode; wherein:
[0008] 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;
[0009] A method for fabricating a near-infrared self-driven photodetector based on a Bi2S3 / Si heterojunction includes the following steps:
[0010] (1) Select mica substrate and Si substrate, and clean and dry them;
[0011] (2) Place the mica substrate at the back end of the CVD process, add Bi2O3 powder in the middle and S powder at the front end, set the reaction temperature to 600 °C, introduce gas, and maintain the temperature at 20 °C per minute until it reaches 600 °C for 5 minutes. Then, allow it to cool naturally to room temperature to obtain a Bi2S3 film on the mica.
[0012] (3) Dissolve 9 g of PS in 100 mL of toluene and stir at 600 rpm for 1 hour until completely dissolved;
[0013] (4) Spin-coat the PS solution from step (3) onto the Bi2S3 film grown on the mica substrate;
[0014] (5) Bake the sample obtained in step (4) at 80 °C for 15 minutes to promote the tight adhesion between the PS layer and the Bi2S3 film;
[0015] (6) Drop water droplets onto the top of the sample obtained in step (5), and poke the PS layer from the edge with a sharp object. Water molecules can then penetrate the Bi2S3 film, causing the PS Bi2S3 component to delaminate. Then remove the water droplets from the separated PS Bi2S3 component with a paper towel, pick up the component with tweezers and transfer it to the Si substrate in step (1);
[0016] (7) The PS Bi2S3 component transferred to the Si substrate obtained in step (6) is baked at 80°C for 1 hour to remove water residue;
[0017] (8) The PS Bi2S3 / Si sample obtained in step (7) was baked at 150°C for 30 minutes to promote the bonding of Bi2S3 and Si interface, and then the PS was removed by rinsing with toluene multiple times.
[0018] (9) Dry the sample obtained in step (8) and cover the surface of the Bi2S3 thin film 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 Bi2S3 thin film; 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;
[0019] (10) The metal In electrode was pressed on the metal Pd front electrode and the Si substrate respectively, and the metal Cu wire was led out to complete the fabrication of the device.
[0020] 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.
[0021] Preferably, in step (2), the ratio of Bi2O3 powder to S powder is 1:3, the gas is argon, the flow rate is 30-20 sccm, and the pressure inside the tube is controlled at 80 Pa.
[0022] Preferably, in step (3), the molecular weight of PS is 280,000 g / mol.
[0023] Preferably, in step (4), the spin coating speed is 3000 rpm.
[0024] Preferably, in step (9), 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.
[0025] Preferably, in step (10), 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.
[0026] The aforementioned devices with self-driven photodetector capabilities can be applied in the fabrication of self-driven photodetectors.
[0027] The beneficial technical effects of this invention are:
[0028] This invention develops a self-driven photodetector device by growing a large-area ordered Bi₂S₃ thin film on a mica substrate and transferring it to a silicon wafer to form a Bi₂S₃ / Si heterojunction. Test results show that the fabricated thin film device exhibits significant sensitivity to the visible and near-infrared regions; 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 to existing self-driven photodetectors, the device described in this invention features a simple, non-toxic, and low-cost fabrication method with significant advantages in light response performance, making it widely applicable in the field of photodetectors. Attached Figure Description
[0029] Figure 1 The image shows the XRD characterization pattern of the fabricated device.
[0030] Figure 2 A schematic diagram of the structure used to measure the photodetector performance of the fabricated device.
[0031] Figure 3 The response performance of the device to near-infrared light of different powers when the applied voltage is 0 volts.
[0032] Figure 4 Here is a SEM image of Bi2S3. Detailed Implementation
[0033] This invention utilizes methods such as magnetron sputtering and chemical vapor deposition to prepare a Bi₂S₃ thin film layer on a mica substrate, which is then transferred to a Si wafer. A Pd front electrode is deposited using DC magnetron sputtering, and an In electrode and connecting metal wires are then pressed to form a device. When exposed to light, due to the photoelectric effect and the presence of a built-in electric field, the device exhibits significant near-infrared light response performance at an applied voltage of 0 volts.
[0034] The present invention will now be described in detail with reference to the embodiments and accompanying drawings.
[0035] This invention relates to a near-infrared self-driven photodetector based on a Bi2S3 / Si heterojunction, comprising a large-area ordered Bi2S3 thin film layer and a Si semiconductor 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.
[0036] Furthermore, a mask is placed over the surface of the Bi2S3 thin film layer on the Si substrate, and then the sample is placed in a vacuum chamber. DC magnetron sputtering is used to bombard a Pd target with ionized argon ions to deposit a Pd front electrode on the surface of the Bi2S3 thin film layer. 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 Pd thin film is 20–25 degrees Celsius, and the thickness of the Pd front electrode is 5–15 nanometers.
[0037] 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.
[0038] The fabrication method of the above-mentioned device specifically includes the following steps:
[0039] (1) Select mica substrate and Si substrate and clean them;
[0040] (2) Place the mica substrate into the CVD back end, add 50 mg of Bi2O3 powder in the middle and 150 mg of S powder at the front end, introduce argon gas at 30 sccm, ensure the pressure inside the tube is 80 Pa, start heating, the temperature rise rate is 20 degrees Celsius per minute, hold at 600 degrees Celsius for 5 minutes, and then cool naturally to room temperature to obtain a Bi2S3 film on the mica.
[0041] (3) Dissolve 9 g of PS with a molecular weight of 280,000 g / mol in 100 mL of toluene and stir at 600 rpm for 1 hour until completely dissolved. Then spin-coat the solution onto a Bi2S3 film grown on a mica substrate at 3000 rpm.
[0042] (4) Bake the sample obtained in step (3) at 80 °C for 15 minutes, then drop water droplets on the top of the sample, and poke the PS layer from the edge with a sharp object. Water molecules penetrate the Bi2S3 film, causing the PS Bi2S3 component to delaminate. Then remove the water droplets from the separated PS Bi2S3 component with a paper towel, pick up the component with tweezers and transfer it to the Si substrate in step (1);
[0043] (5) The sample obtained in step (4) is first baked at 80°C for 1 hour to remove water residue, then baked at 150°C for 30 minutes to promote the bonding of Bi2S3 and Si interface, and finally rinsed with toluene multiple times to remove PS.
[0044] (6) Dry the sample obtained in step (5) and cover the surface of the Bi2S3 thin film layer 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;
[0045] (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.
[0046] The aforementioned devices with self-driven photodetector capabilities can be applied in the fabrication of self-driven photodetectors.
[0047] The effects of the present invention are further illustrated below with reference to performance measurement results:
[0048] Figure 1 The XRD pattern of the fabricated device is shown. The XRD pattern indicates that Bi₂S₃ exhibits good crystallinity.
[0049] Figure 2 A schematic diagram of the structure used to measure the photodetector performance of the fabricated device.
[0050] Figure 3 The 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 excellent photoresponse performance and stable performance. At a test voltage of 0 volts, under illumination at wavelengths of 808 nm and 905 nm (dynamic response curves at different optical powers), the on / off ratio of the thin-film device is over 100 times. These characteristics further demonstrate that this thin-film device can be used to develop novel self-driven photodetectors.
[0051] Figure 4 The image shows the SEM characterization of the Bi2S3 thin film. The SEM image reveals that the Bi2S3 thin film is composed of one-dimensional units with an ordered structure.
Claims
1. A near-infrared self-driven photodetector based on a Bi₂S₃ / Si heterojunction, characterized in that: It includes a metal In point electrode, a metal Pd front electrode, a Bi2S3 thin film layer, a Si single crystal substrate, and a metal In back electrode. The Bi2S3 thin film layer is disposed on the surface of the Si substrate, the metal Pd front electrode is on the surface of the Bi2S3 thin film layer, and the metal In electrode is pressed onto the metal Pd front electrode and the surface of the Si substrate, respectively.
2. The near-infrared self-driven photodetector based on a Bi₂S₃ / 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 near-infrared self-driven detection.
3. A method for fabricating a near-infrared self-driven photodetector based on a Bi2S3 / Si heterojunction, characterized in that... Includes the following steps: (1) Select mica substrate and Si substrate, and clean and dry them; (2) Place the mica substrate at the back end of the CVD process, add Bi2O3 powder to the middle end and S powder to the front end, introduce gas, and set the reaction temperature to 600 ℃ with a temperature rise rate of 20 degrees Celsius per minute. Hold the temperature at 600 degrees Celsius for 5 minutes and then allow it to cool naturally to room temperature to obtain a Bi2S3 film on the mica. (3) Dissolve 9 g of PS in 100 mL of toluene and stir at 600 rpm for 1 hour until completely dissolved; (4) Spin-coat the PS solution from step (3) onto the Bi2S3 film grown on the mica substrate; (5) Bake the sample obtained in step (4) at 80 °C for 15 minutes to promote the tight adhesion between the PS layer and the Bi2S3 film; (6) Drop water droplets onto the top of the sample obtained in step (5), and poke the PS layer from the edge with a sharp object. Water molecules can then penetrate the Bi2S3 film, causing the PS Bi2S3 component to delaminate. Then remove the water droplets from the separated PS Bi2S3 component with a paper towel, pick up the component with tweezers and transfer it to the Si substrate in step (1); (7) The PS Bi2S3 component transferred to the Si substrate in step (6) is baked at 80°C for 1 hour to remove water residue; (8) The PS Bi2S3 / Si sample obtained in step (7) was baked at 150°C for 30 minutes to promote the bonding of Bi2S3 and Si interface, and then the PS was removed by rinsing with toluene multiple times. (9) Dry the sample obtained in step (8) and cover the surface of the Bi2S3 thin film 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 Bi2S3 thin film; 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; (10) The In electrode was pressed on the Pd front electrode and the Si substrate respectively, and the Cu wire was led out to complete the fabrication of the device.
4. The method for fabricating a near-infrared self-driven photodetector based on a Bi2S3 / 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 near-infrared self-driven photodetector based on a Bi2S3 / Si heterojunction according to claim 3, characterized in that: In step (2), the ratio of Bi2O3 powder to S powder is 1:3, the gas is argon, the flow rate is 30-20 sccm, and the pressure inside the tube is controlled at 80 Pa.
6. The method for fabricating a near-infrared self-driven photodetector based on a Bi₂S₃ / Si heterojunction according to claim 3, characterized in that: In step (3), the molecular weight of PS is 280,000 g / mol; in step (4), the spin coating speed is 3,000 rpm.
7. The method for fabricating a near-infrared self-driven photodetector based on a Bi₂S₃ / Si heterojunction according to claim 3, characterized in that: In step (9), the mask is made of stainless steel with a thickness of 0.1 mm, a size of 12 mm × 12 mm, and a aperture size of 5 mm × 5 mm; the vacuum level of the vacuum chamber is 5 × 10⁻⁵ Pascals, and the vacuum condition is achieved by a two-stage vacuum pump consisting of a mechanical pump and a molecular pump.
8. The method for fabricating a near-infrared self-driven photodetector based on a Bi₂S₃ / Si heterojunction according to claim 3, characterized in that: In step (10), 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.