Flexible vacuum ultraviolet photoelectric detector and preparation method thereof
By combining liquid phase exfoliation and radio frequency magnetron sputtering, hexagonal boron nitride nanosheet films were prepared on flexible substrates, solving the problem of poor film adhesion and enabling the fabrication of high-performance, large-scale flexible vacuum ultraviolet photodetectors with good photoelectric response and mechanical flexibility.
Patent Information
- Application Number
- CN202511291187.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-10
- Publication Date
- 2025-12-16
AI Technical Summary
In existing technologies, hexagonal boron nitride nanosheet films prepared by liquid phase exfoliation have poor adhesion to flexible substrates, which makes the films easy to fall off during subsequent electrode manufacturing processes, making it difficult to achieve high-performance and large-scale fabrication of flexible vacuum ultraviolet photodetectors.
Hexagonal boron nitride nanosheets were prepared by liquid phase exfoliation and formed into a thin film at the oil-water interface through self-assembly. An hBN layer was deposited on the self-assembled layer by radio frequency magnetron sputtering. Subsequently, a metal electrode was deposited by photolithography to form a flexible vacuum ultraviolet photodetector with a self-assembled layer, a sputtered layer and a metal electrode layer.
A flexible boron nitride thin film was rapidly prepared at room temperature, improving the adhesion between the film and the substrate. The film can withstand subsequent processes without falling off, and a deep ultraviolet photodetector with good photoelectric response and mechanical flexibility was prepared.
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Figure CN121152334A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of photoelectric detectors, specifically to a flexible vacuum ultraviolet photoelectric detector and its fabrication method. Background Technology
[0002] The wavelength range of ultraviolet light is 10-400 nm, while the vacuum ultraviolet (VUV) spectrum ranges from 10-200 nm. Ultraviolet light in this range is strongly absorbed by oxygen in the air and can only propagate in a vacuum. High-sensitivity VUV detectors are of great significance in fields such as space science, radiation monitoring, the electronics industry, and basic science. Against this backdrop, hexagonal boron nitride (hBN), with its wide bandgap of approximately 5.97 eV and corresponding intrinsic absorption limit of approximately 207 nm, covers the critical VUV window of 180-207 nm, making it an ideal material with excellent response characteristics to VUV ultraviolet light.
[0003] Traditional CVD methods for growing hBN require high-temperature environments, far exceeding the heat resistance limits of flexible substrates, and are incompatible with the disordered lattice on the surface of flexible substrates, resulting in a fundamental obstacle to direct growth on flexible substrates. Therefore, the industry generally uses exfoliation or wet transfer techniques to fabricate flexible devices. However, repeated folding of the tape during mechanical exfoliation can lead to the breakage of the thin film sheets, while the chemical processing in wet transfer carries the risk of solvent corrosion or dissolution of the film, and mechanical stress during the transfer process can easily cause cracks, wrinkles, and dislocations in the film. Liquid phase exfoliation and other methods can directly fabricate hBN films on flexible substrates, reducing damage to the film; however, films formed through simple self-assembly or stacking are only bonded to the flexible substrate by weak van der Waals forces, resulting in extremely poor adhesion. This leads to large-area detachment of the nanosheet film during subsequent photolithography, cleaning, and other processes, causing a significant decrease in the performance of the fabricated devices.
[0004] Therefore, solving the adhesion problem of hBN nanosheet films prepared by liquid phase method on flexible substrates has become a key technical bottleneck for realizing high-performance, large-scale fabrication of flexible hBN photodetectors. Summary of the Invention
[0005] To address the technical challenge of poor adhesion between the thin film transferred via liquid phase exfoliation and the flexible substrate, leading to easy film detachment during subsequent electrode fabrication processes, this invention aims to provide a flexible vacuum ultraviolet photodetector and its fabrication method. This method utilizes liquid phase exfoliation to prepare boron nitride nanosheets (BNNSs), forms a boron nitride nanosheet thin film at the oil-water interface through self-assembly, and transfers it onto a flexible substrate. A thin hBN layer is deposited on the surface of the self-assembled nanosheet thin film using low-power radio frequency magnetron sputtering. Finally, a metal electrode is successfully fabricated on the thin film using photolithography evaporation with minimal nanosheet detachment, thus achieving the fabrication of a deep ultraviolet (wavelength <200 nm) flexible photodetector.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A flexible vacuum ultraviolet photodetector includes a self-assembled layer, a sputtered layer, and a metal electrode layer disposed sequentially from bottom to top on a flexible substrate, wherein the self-assembled layer and the sputtered layer are made of hexagonal boron nitride.
[0007] A method for fabricating a flexible vacuum ultraviolet photodetector includes: Hexagonal boron nitride nanosheet dispersions are used to form self-assembled layers through oil-water self-assembly. Transferring the self-assembled layer onto a flexible substrate; A hexagonal boron nitride nanosheet dispersion was sputtered onto the self-assembled layer by radio frequency magnetron sputtering to form a hexagonal boron nitride thin film. Interdigitated electrode patterns were photolithographically etched onto the sputtered layer, and Ni electrodes were deposited onto the sputtered layer using electron beam evaporation to obtain a flexible vacuum ultraviolet photodetector.
[0008] Furthermore, the hexagonal boron nitride nanosheet dispersion is used to form a self-assembled layer through oil-water self-assembly, including the following steps: adding an organic solvent to the hexagonal boron nitride nanosheet dispersion, and after the organic solvent and water interface are formed, adding an alcohol solvent dropwise to form a boron nitride nanosheet film at the interface.
[0009] Furthermore, the organic solvent is n-hexane.
[0010] Furthermore, the alcohol solvent is ethanol.
[0011] Furthermore, the volume ratio of the hexagonal boron nitride nanosheet dispersion, the organic solvent, and the alcohol solvent is 25-40:10-20:5-10.
[0012] Furthermore, the conditions for RF magnetron sputtering are: nitrogen flow rate of 5-15 sccm, argon flow rate of 20-40 sccm, sputtering power of 50-100 W, sputtering temperature of 150-300℃, and background vacuum of less than 1.0 × 10⁻⁶. -4 Pa, the growth pressure is 0.6 Pa.
[0013] Furthermore, the hexagonal boron nitride nanosheet dispersion was prepared by the following process: 20-50 nm boron nitride nanosheets were prepared by liquid phase exfoliation, and water was used as the solvent to obtain the hexagonal boron nitride nanosheet dispersion.
[0014] Furthermore, the electrode width in the interdigitated electrode pattern is 15-25 μm, and the electrode spacing is 10-15 μm.
[0015] Furthermore, the thickness of the electron beam deposited Ni electrode is 60-70 nm.
[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This detector can be rapidly fabricated at room temperature using a liquid-phase exfoliation self-assembly method, offering simplicity and ease of large-scale production. A sputtered layer is formed via radio frequency magnetron sputtering, serving a dual purpose: firstly, the sputtered hBN bombards the nanosheet surface, strengthening the bond between the film and the flexible substrate and significantly improving the adhesion of the entire hBN film to the substrate; secondly, it forms a continuous surface, protecting the underlying nanosheet film and allowing it to withstand subsequent photolithography and development processes without detachment, further enhancing the adhesion between the boron nitride film and the flexible substrate. Finally, metal electrodes were successfully fabricated on the film using photolithography evaporation with minimal nanosheet detachment, thus achieving the fabrication of a deep ultraviolet (wavelength <200 nm) flexible photodetector.
[0017] The detector of this invention exhibits excellent photoelectric response under deep ultraviolet light (wavelength < 200 nm) irradiation and bending with different radii of curvature. The detector has a photocurrent of 1.12 nA and 1.71 pA, a photocurrent-to-darkness ratio of 655, and rise and fall times of 200 ms and 99 ms, indicating good signal-to-noise ratio and detection sensitivity. Furthermore, when the device is subjected to extreme bending, the photocurrent attenuation rate is approximately 10%, demonstrating good mechanical flexibility. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the flexible vacuum ultraviolet photodetector device structure of the present invention, wherein (a) is a schematic diagram and (b) is an exploded view; In the figure, 1-flexible substrate; 2-self-assembled layer; 3-sputtered layer; 4-metal electrode layer; Figure 2 These are the IV curves of the flexible vacuum ultraviolet photodetector device prepared in Example 1 of this invention under dark conditions and 185 nm light illumination. Figure 3 This is the IT curve of the flexible vacuum ultraviolet photodetector device prepared in Example 1 of the present invention under 185 nm light irradiation; Figure 4 This is a graph showing the trend of photocurrent variation of the flexible vacuum ultraviolet photodetector device prepared in Embodiment 1 of the present invention under different radii of curvature. Figure 5 This is a graph showing the photocurrent variation trend of the flexible vacuum ultraviolet photodetector device prepared in Embodiment 2 of the present invention under different radii of curvature. Figure 6 This is the IV curve of the flexible vacuum ultraviolet photodetector device prepared in Comparative Example 1 of the present invention under 185 nm light irradiation. Detailed Implementation
[0019] To enable those skilled in the art to better understand the present invention, it will be described in detail with reference to the accompanying drawings and specific embodiments.
[0020] like Figure 1 As shown in (a) and (b), the flexible vacuum ultraviolet photodetector of the present invention includes: Substrate layer, the substrate layer is a flexible substrate 1; Self-assembled layer 2, the self-assembled layer is located on the substrate layer, and the self-assembled layer is a self-assembled hBN thin film; Sputtered layer 3 is located on self-assembled layer 2; the sputtered layer is a sputtered hBN thin film; Metal electrode layer 4, which is located on sputtered layer 3.
[0021] The detection wavelength of the flexible vacuum ultraviolet photodetector of the present invention is located in the vacuum ultraviolet light band, with a wavelength of less than 200 nm.
[0022] The photoresponse material of the flexible vacuum ultraviolet photodetector of the present invention is hexagonal boron nitride (hBN).
[0023] The method for fabricating the flexible vacuum ultraviolet photodetector of the present invention includes the following steps: S1. A large number of hexagonal boron nitride nanosheets (BNNSs) were prepared by liquid phase exfoliation, and boron nitride nanosheets with a size of mainly 20-50 nm were collected from the supernatant after centrifugation. Water was used as a solvent to prepare a hexagonal boron nitride nanosheet dispersion, i.e., a BNNSs dispersion.
[0024] In step S1, 450 mg of hexagonal boron nitride (hBN) powder is dispersed in deionized water and ultrasonically treated in a water bath at a frequency of 30-60 Hz for 12-21 h to achieve the stripping of BNNSs and obtain a BNNSs suspension. Then, the BNNSs suspension is centrifuged at a centrifuge speed of 3000-7000 rpm, and 60% of the supernatant is taken as the BNNSs dispersion.
[0025] S2. The BNNSs dispersion is used to form a boron nitride nanosheet film, i.e., a self-assembled layer (i.e., a self-assembled hBN film), through oil-water self-assembly. The self-assembled layer is transferred to the substrate (i.e., flexible substrate 1). A hexagonal boron nitride film is sputtered onto the self-assembled layer by radio frequency magnetron sputtering to form a sputtering layer 3 (i.e., a sputtered hBN film) to improve the adhesion between the film and the substrate.
[0026] In step S2, 10-20 ml of the organic solvent n-hexane is added to 25-40 ml of BNNSs dispersion. After the n-hexane / water interface is formed, 5-10 ml of ethanol is added dropwise to form a boron nitride nanosheet film at the oil-water interface.
[0027] The specific conditions for radio frequency magnetron sputtering are as follows: nitrogen flow rate of 5-15 sccm, argon flow rate of 20-40 sccm, sputtering power of 50-100 W, sputtering temperature of 150-300℃, and background vacuum of less than 1.0×10⁻⁶. -4 Pa, the growth pressure is 0.6 Pa.
[0028] S3. The interdigitated electrode pattern is photolithographically patterned on the thin film using a photolithography plate, and the Ni electrode pattern is deposited on the hexagonal boron nitride thin film by electron beam evaporation to obtain a flexible vacuum ultraviolet photodetector device.
[0029] In step S3, the electrode width in the interdigitated electrode pattern is 15-25 μm, and the electrode spacing is 10-15 μm. The thickness of the Ni electrode deposited by electron beam evaporation is 60-70 nm.
[0030] The following are specific examples.
[0031] Example 1 S1. 450 mg of hBN powder with a transverse size of approximately 25 μm was dispersed in 500 ml of deionized water and sonicated in a water bath at a frequency of 45 Hz for 12 h to obtain a BNNSs suspension. The BNNSs suspension was centrifuged at a speed of 7000 rpm, and 60% of the supernatant was used as the BNNSs dispersion. 30 ml of the BNNSs dispersion was added to a beaker, and 10 ml of n-hexane was added to the beaker. After the n-hexane / water interface was formed, 5 ml of ethanol was slowly added dropwise with a dropper. After a hexagonal boron nitride film was formed at the oil-water interface and the n-hexane evaporated, a self-assembled layer was obtained and transferred to a flexible substrate.
[0032] S2. Using radio frequency magnetron sputtering, an hBN thin film is sputtered onto the self-assembled layer to form a sputtered layer, which improves the adhesion between the self-assembled film and the flexible substrate; the specific sputtering parameters are: background vacuum: less than 1.0 × 10⁻⁶. -4 Pa; Sputtering gas flow rate: 10 sccm of high-purity nitrogen and 30 sccm of high-purity argon; Sputtering target: hBN target; Growth pressure: 0.6 Pa; Substrate temperature: 300℃; Sputtering power: 100 W.
[0033] S3. An interdigitated electrode pattern is photolithographically patterned on the thin film using a photolithography plate. The electrode width in the interdigitated electrode pattern is 15 μm, and the electrode spacing is 10 μm. Electrodes are then photolithographically deposited onto the sputtered layer. The specific parameters for the photolithographic electrodes are as follows: a first spin coating is performed at a speed of 300 r / min for 10 s, followed by a second spin coating at a speed of 4000 r / min for 30 s. Pre-baking time is 100 s, exposure time is 3.7 s, post-baking time is 90 s, and development time is 45 s. The developer on the sputtered layer is then removed using deionization, and the layer is dried with a nitrogen gun. After photolithography, Ni metal electrodes are deposited using electron beam evaporation. The specific parameters for Ni metal deposition are: deposition pressure: less than 2.0 × 10⁻⁶. -3 Pa; Evaporation rate: 0.3 Å / s; Electrode thickness: 70 nm.
[0034] Example 2 S1. 450 mg of hBN powder with a transverse dimension of approximately 25 μm was dispersed in 500 ml of deionized water and sonicated in a water bath at a frequency of 45 Hz for 12 h to obtain a BNNSs suspension. The BNNSs suspension was centrifuged at a speed of 7000 rpm, and 60% of the supernatant was used as the BNNSs dispersion. 30 ml of the BNNSs dispersion was added to a beaker, and 10 ml of n-hexane organic solvent was added to the beaker. After the n-hexane / water interface was formed, 5 ml of ethanol was slowly added dropwise with a dropper. After a hexagonal boron nitride film was formed at the oil-water interface and the n-hexane evaporated, a self-assembled layer was obtained and transferred to a flexible substrate.
[0035] S2. Using radio frequency magnetron sputtering, an hBN thin film is sputtered onto the self-assembled layer to form a sputtered layer, which improves the adhesion between the self-assembled film and the flexible PI substrate; the specific sputtering parameters are: background vacuum: less than 1.0 × 10⁻⁶. - 4 Pa; Sputtering gas flow rate: 10 sccm of high-purity nitrogen and 30 sccm of high-purity argon; Sputtering target: hBN target; Growth pressure: 0.6 Pa; Substrate temperature: 300℃; Sputtering power: 50 W.
[0036] S3. An interdigitated electrode pattern is photolithographically patterned on the thin film using a photolithography plate. The electrode width in the interdigitated electrode pattern is 15 μm, and the electrode spacing is 10 μm. Electrodes are then photolithographically deposited onto the sputtered layer. The specific parameters for the photolithographic electrodes are as follows: a first spin coating is performed at a speed of 300 r / min for 10 s, followed by a second spin coating at a speed of 4000 r / min for 30 s. Pre-baking time is 100 s, exposure time is 3.7 s, post-baking time is 90 s, and development time is 45 s. The substrate is then washed with deionized water to remove the developer and dried with a nitrogen gun. After photolithography, Ni metal electrodes are deposited using electron beam evaporation. The specific parameters for Ni metal deposition are: deposition pressure: less than 2.0 × 10⁻⁶. -3 Pa; Evaporation rate: 0.3 Å / s; Electrode thickness: 70 nm.
[0037] Example 3 S1. 450 mg of hBN powder with a transverse size of approximately 20 μm was dispersed in 500 ml of deionized water and sonicated in a water bath at a frequency of 40 Hz for 16 h to obtain a BNNSs suspension. The BNNSs suspension was centrifuged at 3000 rpm, and 60% of the supernatant was used as the BNNSs dispersion. 25 ml of the BNNSs dispersion was added to a beaker, and 15 ml of n-hexane was added to the beaker. After the n-hexane / water interface was formed, 5 ml of ethanol was slowly added dropwise with a dropper. After a hexagonal boron nitride film was formed at the oil-water interface and the n-hexane evaporated, a self-assembled layer was obtained and transferred to a flexible substrate.
[0038] S2. Using radio frequency magnetron sputtering, an hBN thin film is sputtered onto the self-assembled layer to form a sputtered layer, which improves the adhesion between the self-assembled film and the flexible substrate; the specific sputtering parameters are: background vacuum: less than 1.0 × 10⁻⁶. -4 Pa; Sputtering gas flow rate: 8 sccm of high-purity nitrogen and 20 sccm of high-purity argon; Sputtering target: hBN target; Growth pressure: 0.6 Pa; Substrate temperature: 250 °C; Sputtering power: 100 W.
[0039] S3. Interdigitated electrode patterns are photolithographically patterned on the thin film using a photolithography plate. The electrode width in the interdigitated electrode pattern is 25 μm, and the electrode spacing is 15 μm. Evaporated electrodes are then photolithographically deposited onto the sputtered layer. The specific parameters for the photolithographic electrodes are as follows: a first spin coating is performed at a speed of 300 r / min for 10 s, followed by a second spin coating at a speed of 4000 r / min for 30 s. Pre-baking time is 100 s, exposure time is 3.7 s, post-baking time is 90 s, and development time is 45 s. The developer on the sputtered layer is then removed using deionization, and the layer is dried with a nitrogen gun. After photolithography, Ni metal electrodes are deposited using electron beam evaporation. The specific parameters for Ni metal deposition are: deposition pressure: less than 2.0 × 10⁻⁶. -3 Pa; Evaporation rate: 0.3 Å / s; Electrode thickness: 70 nm.
[0040] Example 4 S1. 450 mg of hBN powder with a transverse dimension of approximately 30 μm was dispersed in 500 ml of deionized water and sonicated in a water bath at a frequency of 60 Hz for 12 h to obtain a BNNSs suspension. The BNNSs suspension was centrifuged at a speed of 5000 rpm, and 60% of the supernatant was used as the BNNSs dispersion. 40 ml of the BNNSs dispersion was added to a beaker, and 20 ml of n-hexane was added to the beaker. After the n-hexane / water interface was formed, 10 ml of ethanol was slowly added dropwise with a dropper. After a hexagonal boron nitride film was formed at the oil-water interface and the n-hexane evaporated, a self-assembled layer was obtained and transferred to a flexible substrate.
[0041] S2. Using radio frequency magnetron sputtering, an hBN thin film is sputtered onto the self-assembled layer to form a sputtered layer, which improves the adhesion between the self-assembled film and the flexible substrate; the specific sputtering parameters are: background vacuum: less than 1.0 × 10⁻⁶. -4 Pa; Sputtering gas flow rate: 15 sccm for high-purity nitrogen and 35 sccm for high-purity argon; Sputtering target: hBN target; Growth pressure: 0.6 Pa; Substrate temperature: 150 °C; Sputtering power: 70 W.
[0042] S3. An interdigitated electrode pattern is photolithographically patterned on the thin film using a photolithography plate. The electrode width in the interdigitated electrode pattern is 15 μm, and the electrode spacing is 12 μm. Evaporation electrodes are then photolithographically deposited onto the sputtered layer. The specific parameters for the photolithographic electrodes are as follows: a first spin coating is performed at a speed of 300 r / min for 10 s, followed by a second spin coating at a speed of 4000 r / min for 30 s. Pre-baking time is 100 s, exposure time is 3.7 s, post-baking time is 90 s, and development time is 45 s. The developer on the sputtered layer is then removed using deionization, and the layer is dried with a nitrogen gun. After photolithography, Ni metal electrodes are deposited using electron beam evaporation. The specific parameters for Ni metal deposition are: deposition pressure: less than 2.0 × 10⁻⁶. -3 Pa; Evaporation rate: 0.3 Å / s; Electrode thickness: 60 nm.
[0043] Example 5 S1. 450 mg of hBN powder with a transverse dimension of approximately 50 μm was dispersed in 500 ml of deionized water and sonicated in a water bath at a frequency of 30 Hz for 21 h to obtain a BNNSs suspension. The BNNSs suspension was centrifuged at a speed of 6000 rpm, and 60% of the supernatant was used as the BNNSs dispersion. 30 ml of the BNNSs dispersion was added to a beaker, and 15 ml of n-hexane was added to the beaker. After the n-hexane / water interface was formed, 8 ml of ethanol was slowly added dropwise with a dropper. After a hexagonal boron nitride film was formed at the oil-water interface and the n-hexane evaporated, a self-assembled layer was obtained and transferred to a flexible substrate.
[0044] S2. Using radio frequency magnetron sputtering, an hBN thin film is sputtered onto the self-assembled layer to form a sputtered layer, which improves the adhesion between the self-assembled film and the flexible substrate; the specific sputtering parameters are: background vacuum: less than 1.0 × 10⁻⁶. -4 Pa; Sputtering gas flow rate: 5 sccm for high-purity nitrogen and 40 sccm for high-purity argon; Sputtering target: hBN target; Growth pressure: 0.6 Pa; Substrate temperature: 200 °C; Sputtering power: 50 W.
[0045] S3. An interdigitated electrode pattern is photolithographically patterned on the thin film using a photolithography plate. The electrode width in the interdigitated electrode pattern is 20 μm, and the electrode spacing is 15 μm. Electrodes are then photolithographically deposited onto the sputtered layer. The specific parameters for the photolithographic electrodes are as follows: a first spin coating is performed at a speed of 300 r / min for 10 s, followed by a second spin coating at a speed of 4000 r / min for 30 s. Pre-baking time is 100 s, exposure time is 3.7 s, post-baking time is 90 s, and development time is 45 s. The developer on the sputtered layer is then removed using deionization, and the layer is dried with a nitrogen gun. After photolithography, Ni metal electrodes are deposited using electron beam evaporation. The specific parameters for Ni metal deposition are: deposition pressure: less than 2.0 × 10⁻⁶. -3 Pa; Evaporation rate: 0.3 Å / s; Electrode thickness: 65 nm.
[0046] Comparative Example 1 S1. 450 mg of hBN powder with a transverse size of approximately 25 μm was dispersed in 500 ml of deionized water and sonicated in a water bath at a frequency of 45 Hz for 12 h to obtain a BNNSs suspension. The BNNSs suspension was centrifuged at a speed of 7000 rpm, and 60% of the supernatant was used as the BNNSs dispersion. 30 ml of the BNNSs dispersion was added to a beaker, and 10 ml of n-hexane organic solvent was added to the beaker. After the n-hexane / water interface was formed, 5 ml of ethanol was slowly added dropwise with a dropper. After a hexagonal boron nitride film was formed at the oil-water interface and the n-hexane evaporated, a self-assembled layer was obtained and transferred onto a flexible substrate.
[0047] S2. Electrodes are photolithographically deposited onto the self-assembled layer. Specific parameters for the photolithographic electrodes are: spin coating speed 1: 300 r / min, time: 10 s; spin coating speed 2: 4000 r / min, time: 30 s; pre-baking time: 100 s; exposure time: 3.7 s; post-baking time: 90 s; development time: 45 s. The developing solution on the substrate is then removed using deionization, and the substrate is dried with a nitrogen gun. After photolithography, Ni metal electrodes are deposited using electron beam evaporation. Specific parameters for Ni deposition are: deposition pressure: less than 2.0 × 10⁻⁶. -3 Pa; Evaporation rate: 0.3 Å / s; Electrode thickness: 70 nm.
[0048] The flexible detectors prepared in Examples 1-2 and the comparative examples were subjected to the following experiments: The flexible vacuum ultraviolet photodetector device prepared in Example 1 was subjected to photoelectric response testing, and IV curves were obtained under 185nm illumination and in the dark. Figure 2 As can be seen, the photocurrent and dark current of the detector at 80 V are 1.12 nA and 1.71 pA, respectively, with a photocurrent-to-dark current ratio of 655, indicating that the fabricated detector device has good photoelectric response under a 185 nm light source. In contrast, the photoelectric response test of the flexible vacuum ultraviolet photodetector device fabricated in Example 1 shows... Figure 6 As can be seen, the photocurrent and dark current of the detector at 80 V are 53 pA and 9.58 pA, respectively, and the photocurrent-dark current ratio is 5.53, indicating that low-power RF magnetron sputtering of hBN thin films can improve the performance of nanosheet thin film detectors.
[0049] The IT curve of the flexible vacuum ultraviolet photodetector device prepared in Example 1 under 185 nm light illumination is shown below. Figure 3 As can be seen, the rise and fall times of the device are 200 ms and 99 ms, respectively, indicating that the fabricated detector has good response characteristics under a 185 nm light source and can generate a photoresponse relatively quickly.
[0050] To measure the photoelectric performance of the detector under different bending conditions, the detector was bent to different degrees to test its photoelectric performance.
[0051] Figure 4 The image shows the IV test results of the flexible vacuum ultraviolet photodetector device prepared in Example 1 at different radii of curvature. The wavelength of the light is 185 nm. The test results show that the photocurrent of the detector does not change significantly under different radii of curvature and has small differences. At the same time, the photocurrent changes the most when it is almost folded in half with R=2.6 cm, decreasing by about 10%, indicating that the device can still maintain good photoelectric response under high bending conditions.
[0052] Figure 5 The image shows the IV test results of the flexible vacuum ultraviolet photodetector device prepared in Example 2 at different radii of curvature. The wavelength of the light is 185 nm. The test results show that the photocurrent of the detector is 1.17 nA and the photocurrent does not change significantly under different radii of curvature, showing small differences. At the same time, when it is almost folded in half, with R=2.6 cm, the photocurrent changes the most, decreasing by about 16%, indicating that the power of RF magnetron sputtering has a certain optimization effect on the device performance.
[0053] This invention utilizes liquid-phase exfoliation to prepare boron nitride nanosheets (BNNSs). A boron nitride nanosheet film is formed at the oil-water interface through self-assembly and then transferred onto a flexible substrate. A thin hBN layer is deposited on the surface of the self-assembled nanosheet film using low-power radio frequency magnetron sputtering. This sputtered layer serves a dual purpose: firstly, the sputtered hBN bombards the nanosheet film surface, resulting in a stronger bond between the film and the flexible substrate, significantly improving the adhesion of the entire hBN film to the substrate; secondly, it forms a continuous surface, protecting the underlying nanosheet film and enabling it to withstand subsequent photolithography, development, and other processes without detachment. Finally, a metal electrode is successfully fabricated on the film using photolithography evaporation with minimal nanosheet detachment, thus realizing the fabrication of a deep ultraviolet (wavelength <200 nm) flexible photodetector.
[0054] The above are merely specific implementation examples of the present invention, representing practical applications based on specific experimental conditions and process parameters, and are not exhaustive limitations on the technical solutions. For those skilled in the art, based on an understanding of the core logic of the present invention, different variations can be made to the technical features of each stage, and these obvious variations should also be within the scope of protection of the present invention.
Claims
1. A flexible vacuum ultraviolet photodetector, characterized in that, It includes a self-assembled layer (2), a sputtered layer (3) and a metal electrode layer (4) arranged sequentially from bottom to top on a flexible substrate (1), wherein the self-assembled layer (2) and the sputtered layer (3) are made of hexagonal boron nitride.
2. A method for fabricating a flexible vacuum ultraviolet photodetector, characterized in that, include: Hexagonal boron nitride nanosheet dispersion was used to form a self-assembled layer (2) through oil-water self-assembly. The self-assembled layer (2) is transferred onto the flexible substrate (1); A hexagonal boron nitride nanosheet dispersion was sputtered onto the self-assembled layer by radio frequency magnetron sputtering to form a hexagonal boron nitride thin film (3). A photolithographic interdigitated electrode pattern is formed on the sputtered layer (3), and a Ni electrode is deposited on the sputtered layer (3) by electron beam evaporation to obtain a flexible vacuum ultraviolet photodetector.
3. The method for fabricating the flexible vacuum ultraviolet photodetector according to claim 2, characterized in that, The hexagonal boron nitride nanosheet dispersion is used to form a self-assembled layer through oil-water self-assembly, including the following steps: adding an organic solvent to the hexagonal boron nitride nanosheet dispersion, and after the organic solvent and water interface are formed, adding an alcohol solvent dropwise to form a boron nitride nanosheet film at the interface.
4. The method for fabricating the flexible vacuum ultraviolet photodetector according to claim 3, characterized in that, The organic solvent is n-hexane.
5. The method for fabricating the flexible vacuum ultraviolet photodetector according to claim 3, characterized in that, The alcohol solvent is ethanol.
6. The method for fabricating the flexible vacuum ultraviolet photodetector according to claim 3, characterized in that, The volume ratio of the hexagonal boron nitride nanosheet dispersion, organic solvent, and alcohol solvent is 25-40:10-20:5-10.
7. The method for fabricating the flexible vacuum ultraviolet photodetector according to claim 3, characterized in that, The conditions for radio frequency magnetron sputtering are: nitrogen flow rate of 5-15 sccm, argon flow rate of 20-40 sccm, sputtering power of 50-100 W, sputtering temperature of 150-300℃, and background vacuum of less than 1.0×10⁻⁶. -4 Pa, the growth pressure is 0.6 Pa.
8. The method for fabricating the flexible vacuum ultraviolet photodetector according to claim 3, characterized in that, The hexagonal boron nitride nanosheet dispersion was prepared by the following process: 20-50 nm boron nitride nanosheets were prepared by liquid phase exfoliation, and water was used as the solvent to obtain the hexagonal boron nitride nanosheet dispersion.
9. The method for fabricating the flexible vacuum ultraviolet photodetector according to claim 3, characterized in that, The electrode width in the interdigitated electrode pattern is 15-25 μm, and the electrode spacing is 10-15 μm.
10. The method for fabricating the flexible vacuum ultraviolet photodetector according to claim 3, characterized in that, The thickness of the Ni electrode deposited by electron beam evaporation is 60-70 nm.