Single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire, dual-band ultraviolet photoelectric detector, preparation method and application

Abstract

The invention belongs to the technical field of ultraviolet photoelectric detectors, and relates to a single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire, a dual-waveband ultraviolet photoelectric detector, a preparation method and application. The nanowire comprises a SiC nanowire core, an amorphous SiO2 shell layer and Ga2O3 nanoparticles, wherein the SiC nanowire core is coated with the amorphous SiO2 shell layer, the Ga2O3 nanoparticles are attached to the SiO2 shell layer, and a core-shell-satellite structure is formed. According to the invention, by constructing the SiC / SiO2 / Ga2O3 core-shell-satellite nanowire structure, selective recognition and high-performance detection of single-device dual-band UVA and UVC are realized. According to the structure, SiC / SiO2 / Ga2O3 radial heterojunctions, the passivation effect of an amorphous SiO2 shell layer and the synergistic effect of the Ga2O3 nanoparticles on the strong absorption capacity of UVC are combined.

Description

Technical Field

[0001] This invention belongs to the field of ultraviolet photodetector technology, and relates to a single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire, a dual-band ultraviolet photodetector, its preparation method, and its application. Background Technology

[0002] Ultraviolet (UV) photodetectors are widely used in environmental monitoring, military early warning, biomedicine, optical communication, and flame detection. They can efficiently and accurately detect UV radiation across different wavelength ranges, especially in the UVA (320–400 nm) and UVC (200–280 nm) bands. Traditional UV detectors typically require multiple detector chips made of different materials or combined with filters to achieve multi-band response, resulting in high system complexity, low integration, and high energy consumption, making it difficult to meet the demands for miniaturization and intelligence. Therefore, developing novel structures and materials that can achieve selective detection of both UVA and UVC bands in a single device is of great significance.

[0003] Silicon carbide (SiC), as a typical wide-bandgap semiconductor material, possesses high thermal stability, high breakdown electric field strength, good radiation resistance, and fast electron drift velocity, making it an ideal material for constructing ultraviolet detectors. Compared to bulk materials, one-dimensional SiC nanowires exhibit quantum confinement effects, a large specific surface area, excellent light-harvesting capabilities, and efficient directional carrier transport characteristics, resulting in superior performance in the field of ultraviolet detection. However, the bandgap of SiC (~2.4–3.3 eV) determines that its primary response is in the UVA band, with limited absorption efficiency for shorter wavelength UVC light, making multi-band identification difficult.

[0004] In recent years, improving the ultraviolet response performance of SiC by constructing heterojunctions or composite structures has become a research hotspot. However, most existing SiC-based heterojunctions can only enhance the response capability of a fixed wavelength band, and generally lack the ability to achieve distinguishable detection of UVA / UVC dual bands in a single ultraviolet optoelectronic device. In addition, the interface modulation and bandgap matching of complex nanostructures have not been effectively solved. Therefore, developing a novel device structure with a novel structure, tunable bandgap, and the ability to accurately distinguish UVA and UVC and achieve high-performance detection in a single SiC device has significant scientific and application value. Summary of the Invention

[0005] Based on the problems and defects existing in the prior art, this invention provides a single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire. The dual-band ultraviolet photodetector prepared using its hierarchical heterostructure can achieve fine bandgap control, selectively identify and separate UVA and UVC light; it has high gain, ultra-high external quantum efficiency and fast response performance under UVC light; and it features synergistic enhancement of interface defect suppression, carrier separation enhancement and cross-interface tunneling effect.

[0006] The specific technical solution provided by this invention is as follows: In a first aspect, the present invention provides a single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire, wherein the nanowire comprises a SiC nanowire core, an amorphous SiO2 shell covering the SiC nanowire core, and Ga2O3 nanoparticles attached to the SiO2 shell, forming a core-shell-satellite structure.

[0007] Secondly, the present invention provides a method for preparing the single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire, comprising the following steps: SiC nanowires were soaked in acetone solution and subjected to ultrasonic treatment to expose unsaturated dangling bonds and high-energy active sites on the surface of the SiC nanowires, while inducing the formation of wrinkled stripe structures on the surface. The treated SiC nanowires were mixed with Ga(NO3)3·6H2O and heated to 800℃~900℃ under vacuum sealing conditions at a heating rate of 3℃ / min~5℃ / min, and held at that temperature for 3h~5h. After cooling, they were annealed in air at 400℃~600℃ for 1h~3h. During this process, a uniform amorphous SiO2 shell was formed in situ on the surface of the SiC nanowires, and Ga2O3 nanoparticles were attached to and grew on the amorphous SiO2 shell, forming SiC / SiO2 / Ga2O3 composite nanowires with a "core-shell satellite" multi-level structure.

[0008] The purpose of acetone treatment is to remove impurities adsorbed on the surface of SiC nanowires, thereby exposing a large number of unsaturated dangling bonds and high-energy surface sites. These surface sites significantly improve the surface reactivity of SiC nanowires, facilitating subsequent efficient interfacial reactions. Furthermore, acetone ultrasonic treatment induces wrinkled stripes on the SiC nanowire surface. These stripes are wrinkled textures formed after surface roughening, primarily originating from the unevenness created by the slight corrosion of the SiC surface by acetone. These stripes significantly increase surface roughness and active site density. Simultaneously, the rough wrinkled structure enhances the mechanical interlocking between interfaces, thereby improving the stability of the overall core-shell-satellite structure and providing the necessary structural basis for constructing high-performance SiC / SiO2 / Ga2O3 nanowire ultraviolet photodetectors. Therefore, acetone treatment of SiC nanowires helps form a uniform amorphous SiO2 shell in subsequent high-temperature solid-state reactions and promotes high-density and uniform nucleation of Ga2O3 nanoparticles.

[0009] In a high-temperature, vacuum-sealed quartz tube at 800–900 °C, Ga(NO3)3•6H2O completely decomposes, generating Ga2O3, NO2, and O2. During this process, NO2 acts as an oxidant, reacting with the SiC surface to form silicon-containing intermediates. These intermediates are subsequently further oxidized to form SiO2. Since 800–900 °C is much lower than the growth temperature of crystalline SiO2, the formed SiO2 oxide layer is amorphous and uniformly coats the surface of the SiC nanowires. This amorphous SiO2 effectively reduces the dangling bond density on the SiC surface, decreases recombination centers, acts as a surface passivation agent, and alleviates the lattice mismatch problem between SiC and Ga2O3. Furthermore, amorphous SiO2 has high surface activity and a large specific surface area, providing a better structural basis for subsequent Ga2O3 deposition. During vapor deposition, gaseous Ga2O3 molecules adsorb onto the highly surface-active amorphous SiO2 surface and undergo a chemical reaction. When Ga2O3 molecules accumulate to a certain extent on the surface, initial aggregation and nucleation occur, forming tiny particles. As more Ga2O3 molecules continue to deposit, the initial nucleated particles begin to grow, forming uniform Ga2O3 nanoparticles on the surface of SiC / SiO2 nanowires. Subsequently, in an oxygen-rich air atmosphere of 400–600 °C, oxygen molecules are adsorbed onto the SiC / SiO2 / Ga2O3 surface in large quantities, resulting in a more complete oxidation reaction. This promotes the further growth of amorphous SiO2 and Ga2O3 nanoparticles, ultimately yielding SiC / SiO2 / Ga2O3 core-shell-satellite nanowires.

[0010] Preferably, the ultrasonic treatment time is 20-30 minutes.

[0011] Preferably, the molar ratio of the treated SiC nanowires to Ga(NO3)3·6H2O is 3~5:1.

[0012] Preferably, the Ga2O3 nanoparticles have a diameter of 10~17 nm and the amorphous SiO2 shell has a thickness of 8~13 nm.

[0013] Preferably, the ratio of SiC nanowires to acetone solution is 1~2 mg: 5~10 mL.

[0014] Preferably, after ultrasonic treatment, the sample is washed 3-5 times by centrifugation with deionized water, and then dried in a vacuum drying oven at 60 °C for 4-8 h to obtain the treated SiC nanowires.

[0015] Thirdly, the present invention provides a dual-band ultraviolet photodetector made of a single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire, comprising: Si / SiO2 substrate; Nickel electrodes disposed at both ends of the Si / SiO2 substrate; and The single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire disposed on the Si / SiO2 substrate has its two ends connected to the nickel electrode.

[0016] Preferably, the spacing between the nickel electrodes at both ends of the Si / SiO2 substrate is 4μm to 10μm.

[0017] Fourthly, this invention provides a method for fabricating a dual-band ultraviolet photodetector using a single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire, comprising the following steps: The SiC / SiO2 / Ga2O3 core-shell-satellite nanowires were dispersed and then drop-coated onto the Si / SiO2 substrate, dried, and individual nanowires were screened out. Two nickel electrodes are fabricated on the Si / SiO2 substrate, and the single nanowire is transferred between the two nickel electrodes to form an electrical connection, thus obtaining a pre-assembled device. The pre-assembled device is subjected to vacuum annealing to form an ohmic contact between the nanowire and the nickel electrode, thus obtaining the dual-band ultraviolet photodetector.

[0018] Preferably, the SiC / SiO2 / Ga2O3 core-shell-satellite nanowires are dispersed in isopropanol and ultrasonically treated for 30-60 minutes; the ratio of SiC / SiO2 / Ga2O3 nanowires to isopropanol is 0.05-0.10 mg: 2-3 mL.

[0019] Preferably, the drying conditions after drop coating are drying at 60°C for 30 to 60 minutes; the nickel electrode is obtained by vacuum evaporation deposition.

[0020] Preferably, the suspension is drop-coated onto a Si / SiO2 sheet and dried in an oven at 60 °C for 30–60 minutes; the substrate surface is observed under an optical microscope to screen out well-dispersed single nanowires of appropriate length; the dried Si / SiO2 sheet is used as a mask and a 600-mesh copper grid is used to deposit nickel electrodes in a vacuum evaporation apparatus; subsequently, polydimethylsiloxane (PDMS) is used to precisely transfer the single nanowires between the nickel electrodes on a two-dimensional transfer platform.

[0021] Preferably, the nanowire is annealed in a vacuum annealing furnace at 600-800 °C for 20-40 minutes to ensure good ohmic contact between the nanowire and the electrode, thereby successfully fabricating a single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire dual-band ultraviolet photodetector.

[0022] Fifthly, the present invention provides an application of the dual-band ultraviolet photodetector in detecting ultraviolet radiation in different wavelength ranges.

[0023] Preferably, the dual-band ultraviolet photodetector is used to distinguish between ultraviolet radiation of 320~400 nm and 200~280 nm.

[0024] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages: This invention achieves selective recognition and high-performance detection of dual-band UVA and UVC in a single device by constructing a SiC / SiO2 / Ga2O3 core-shell-satellite nanowire structure. This structure combines the synergistic effect of a SiC / SiO2 / Ga2O3 radial heterojunction, the passivation effect of the amorphous SiO2 shell, and the strong UVC absorption capability of Ga2O3 nanoparticles. Its ultraviolet photoelectric performance test results show that it achieves high performance at 365 nm (UVA) ultraviolet light (245 mW / cm²). 2 At a bias voltage of 10 V and 10 V, the device achieved 5.3 × 10⁻⁶. 4 High A / W responsivity; at 254 nm (UVC) ultraviolet light (67 mW / cm²). 2At a bias voltage of 5 V, a responsivity of 1547.06 A / W was achieved, reaching a high of 7.42 × 10⁻⁶. 5 The external quantum efficiency (EQE) is 98%, and the response and recovery times are fast (98 / 93 ms). At the same optical power density (67 mW / cm²), it achieves this. 2 Under ultraviolet irradiation at different wavelengths of 254 nm and 365 nm, the photocurrent of the device at 254 nm is significantly higher than that at 365 nm. The selective recognition and high-performance detection of the dual-band UVA and UVC are mainly due to the multiple synergistic effects of the structure: (1) The SiC nanowire core layer serves as the central carrier transport channel. Its wide bandgap characteristics, high thermal stability and excellent electron mobility enable it to complete the generation and rapid transport of the main photogenerated carriers under 365 nm (UVA) irradiation, which is the basis for the stable operation of the device under high temperature and strong light conditions; (2) The amorphous SiO2 intermediate layer not only acts as a passivation layer to effectively reduce surface recombination centers, but also acts as a carrier tunnel layer to promote the separation of interface charges; (3) Ga2O3 nanoparticles (bandgap of about 4.7 eV) act as sensitizers to enhance the response to the UVC (254 nm) band. In summary, SiC / SiO2 / Ga2O3 core-shell-satellite nanowires utilize the multiple synergistic effects of their structure to achieve distinguishable detection of UVA and UVC and high-performance ultraviolet response, providing an important technical path for developing next-generation adaptive, multifunctional, and integrable ultraviolet photoelectric detection systems. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 The images show the structural characterization of the SiC / SiO2 / Ga2O3 core-shell-satellite nanowires in this invention. a is an image of the surface morphology of the SiC nanowires after acetone treatment; b-d are images of the surface morphology of the SiC / SiO2 / Ga2O3 core-shell-satellite nanowires; e is a high-resolution transmission electron microscope (HRTEM) image of the SiC / SiO2 / Ga2O3 heterojunction interface; f is the electron diffraction (SAED) pattern of region 2 in image e; g-j are magnified HRTEM images of regions 1, 2, 3, and 4 in image e, respectively; k is the XRD pattern of the SiC / SiO2 / Ga2O3 core-shell-satellite nanowires; and l is a spatial distribution diagram of Si, C, O, and Ga elements in the nanowires.

[0027] Figure 2This is a schematic diagram of the dual-band ultraviolet photodetector device using a single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire in this invention.

[0028] Figure 3 The photoelectric properties of the dual-band ultraviolet photodetector made of a single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire in this invention are shown under different ultraviolet light irradiation conditions. a) is a graph showing the relationship between the responsivity (R) and external quantum efficiency (EQE) of the device under 365 nm illumination and 10 V bias voltage as a function of optical power density; b) is a graph showing the response and recovery time of the device under 254 nm illumination and 5 V bias voltage; c) is a graph showing the relationship between R and EQE of the device under 254 nm illumination and 5 V bias voltage as a function of optical power density; d) is a graph showing the relationship between the device under the same optical power density of 67 mW / cm². 2 The IV characteristic curves are shown under different 254 nm and 365 nm illumination conditions. e is the stability test of the device under 254 nm illumination (67 mW / cm²) after being placed in an air environment for three months (unpackaged device). Detailed Implementation

[0029] The technical solution of the present invention will be described below with reference to the embodiments, but the present invention is not limited to the following embodiments.

[0030] Unless otherwise specified, the experimental and detection methods described in each embodiment are conventional methods; unless otherwise specified, the reagents and materials described are commercially available.

[0031] The present invention provides a single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire, which includes a SiC nanowire core, an amorphous SiO2 shell covering the core, and Ga2O3 nanoparticles attached to the SiO2 shell to form a core-shell-satellite structure.

[0032] This invention also designs a dual-band ultraviolet photodetector based on a single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire structure. The core innovation of this device lies in its unique hierarchical multi-level heterostructure design. The nanowire heterostructure constructed in this invention includes: a SiC nanowire core, an amorphous SiO2 intermediate layer formed through self-oxidation of the surface, and subsequently, Ga2O3 nanoparticles attached and grown on the SiO2 layer under high-temperature processing and vacuum encapsulation, thus forming a unique "core-shell-satellite" multi-level architecture. This structural design allows the device to generate photocurrent solely from the SiC core under 365 nm (UVA) excitation, while under 254 nm (UVC) irradiation, SiC and Ga2O3 simultaneously absorb incident photons, producing a synergistic enhancement effect, achieving dual-source enhanced UVC high-sensitivity detection. Therefore, through the above precise bandgap structure design, the single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire ultraviolet photodetector has achieved the identification and high-sensitivity detection of UVA and UVC, laying the foundation for the development of the next generation of adaptive, multifunctional ultraviolet photodetector systems.

[0033] Example 1 This embodiment provides SiC / SiO2 / Ga2O3 core-shell-satellite nanowires, which are prepared according to the following steps: (1) 20 mg of SiC nanowire aerogel was immersed in 100 mL of acetone solution and sonicated for 30 minutes. After treatment, the sample was washed 5 times by centrifugation with deionized water. The washed sample was placed in a vacuum drying oven at 60 °C for 8 hours to obtain the treated SiC nanowires;

[0034] (2) The treated SiC nanowires and uniformly ground Ga(NO3)3•6H2O were evenly spread in a quartz tube at a molar ratio of 3:1, and the quartz tube was vacuum sealed. Then, the sealed quartz tube was placed in a muffle furnace and heated to 800 ℃ at a heating rate of 3 ℃ / min and held at that temperature for 3 hours, and then allowed to cool naturally in the furnace. After cooling, the sample was taken out and transferred to a crucible, and annealed in an air atmosphere at 600 ℃ for 3 hours to obtain SiC / SiO2 / Ga2O3 nanowires.

[0035] Example 2 This embodiment provides SiC / SiO2 / Ga2O3 core-shell-satellite nanowires, which are prepared according to the following steps: (1) 20 mg of SiC nanowire aerogel was immersed in 100 mL of acetone solution and sonicated for 20 minutes. After treatment, the sample was washed 5 times by centrifugation with deionized water. The washed sample was placed in a vacuum drying oven at 60 °C for 8 hours to obtain the treated SiC nanowires;

[0036] (2) The treated SiC nanowires and uniformly ground Ga(NO3)3•6H2O were evenly spread in a quartz tube at a molar ratio of 3:1, and the quartz tube was vacuum sealed. Then, the sealed quartz tube was placed in a muffle furnace and heated to 800 ℃ at a heating rate of 3 ℃ / min and held at that temperature for 3 hours, and then allowed to cool naturally in the furnace. After cooling, the sample was taken out and transferred to a crucible, and annealed in an air atmosphere at 600 ℃ for 3 hours to obtain SiC / SiO2 / Ga2O3 nanowires.

[0037] Example 3 This embodiment provides SiC / SiO2 / Ga2O3 core-shell-satellite nanowires, which are prepared according to the following steps: (1) 20 mg of SiC nanowire aerogel was immersed in 100 mL of acetone solution and sonicated for 30 minutes. After treatment, the sample was washed 5 times by centrifugation with deionized water. The washed sample was placed in a vacuum drying oven at 60 °C for 8 hours to obtain the treated SiC nanowires;

[0038] (2) The treated SiC nanowires and uniformly ground Ga(NO3)3•6H2O were evenly spread in a quartz tube at a molar ratio of 5:1, and the quartz tube was vacuum sealed. Then, the sealed quartz tube was placed in a muffle furnace and heated to 800 ℃ at a heating rate of 3 ℃ / min and held at that temperature for 3 hours, and then allowed to cool naturally in the furnace. After cooling, the sample was taken out and transferred to a crucible, and annealed in an air atmosphere at 600 ℃ for 3 hours to obtain SiC / SiO2 / Ga2O3 nanowires.

[0039] Example 4 This embodiment provides SiC / SiO2 / Ga2O3 core-shell-satellite nanowires, which are prepared according to the following steps: (1) 20 mg of SiC nanowire aerogel was immersed in 100 mL of acetone solution and sonicated for 30 minutes. After treatment, the sample was washed 5 times by centrifugation with deionized water. The washed sample was placed in a vacuum drying oven at 60 °C for 8 hours to obtain the treated SiC nanowires;

[0040] (2) The treated SiC nanowires and uniformly ground Ga(NO3)3•6H2O were evenly spread in a quartz tube at a molar ratio of 3:1, and the quartz tube was vacuum sealed. Then, the sealed quartz tube was placed in a muffle furnace and heated to 900 ℃ at a heating rate of 5 ℃ / min and held at that temperature for 5 hours, and then allowed to cool naturally in the furnace. After cooling, the sample was taken out and transferred to a crucible, and annealed in air at 600 ℃ for 3 hours to obtain SiC / SiO2 / Ga2O3 nanowires.

[0041] Example 5 This embodiment provides SiC / SiO2 / Ga2O3 core-shell-satellite nanowires, which are prepared according to the following steps: (1) 20 mg of SiC nanowire aerogel was immersed in 100 mL of acetone solution and sonicated for 30 minutes. After treatment, the sample was washed 5 times by centrifugation with deionized water. The washed sample was placed in a vacuum drying oven at 60 °C for 8 hours to obtain the treated SiC nanowires;

[0042] (2) The treated SiC nanowires and uniformly ground Ga(NO3)3•6H2O were evenly spread in a quartz tube at a molar ratio of 3:1, and the quartz tube was vacuum sealed. Then, the sealed quartz tube was placed in a muffle furnace and heated to 800 ℃ at a heating rate of 3 ℃ / min and held at that temperature for 3 hours, and then allowed to cool naturally in the furnace. After cooling, the sample was taken out and transferred to a crucible, and annealed in an air atmosphere at 400 ℃ for 1 hour to obtain SiC / SiO2 / Ga2O3 nanowires.

[0043] Examples 1-5 successfully prepared SiC / SiO2 / Ga2O3 nanowires with a core-shell-satellite structure. The structural characterization is illustrated using the product from Example 1 as an example. Figure 1 .

[0044] The morphology and structure of the SiC / SiO2 / Ga2O3 nanowires of Example 1 were characterized using transmission electron microscopy (TEM) and X-ray diffraction (XRD). Figure 1Figure a shows the surface morphology of SiC nanowires after acetone treatment. It was found that ultrasonic treatment with acetone induces wrinkled stripes on the SiC nanowire surface. These stripes are wrinkled textures formed after surface roughening, mainly originating from the unevenness created by the slight corrosion of the SiC surface by acetone. These stripes significantly increase surface roughness and active site density. Simultaneously, the rough wrinkled structure enhances the mechanical interlocking between interfaces, thereby improving the stability of the overall core-shell-satellite structure. This provides the necessary structural basis for constructing high-performance SiC / SiO2 / Ga2O3 nanowire ultraviolet photodetectors. Therefore, acetone treatment of SiC nanowires helps form a uniform amorphous SiO2 shell in subsequent high-temperature reactions and promotes high-density and uniform nucleation of Ga2O3 nanoparticles.

[0045] Following a subsequent high-temperature annealing process, a core-shell-satellite structure with good performance was successfully obtained, such as... Figure 1 As shown in Figures b to d. High-resolution transmission electron microscopy (HRTEM) analysis was performed on a single nanowire. Figure 1 (e) reveals the detailed structural features of the SiC / SiO2 / Ga2O3 heterojunction. This structure exhibits a clear radial compositional gradient: a crystalline SiC core is uniformly encapsulated within an amorphous SiO2 interlayer formed in situ by thermal oxidation of the SiC nanowire surface. Dispersed Ga2O3 nanoparticles (10–17 nm in diameter) are firmly attached to the SiO2 shell, exhibiting a well-defined edge structure and low aggregation, demonstrating the effectiveness of the two-step thermal treatment process. This method effectively promotes the controllable nucleation and growth of Ga2O3, forming a uniformly distributed interface structure firmly bonded to the amorphous SiO2 shell.

[0046] To further investigate the heterostructure of SiC / SiO2 / Ga2O3 nanowires Figure 1 The red-boxed areas 1, 2, 3, and 4 in Figure e underwent more detailed high-resolution analysis. For example... Figure 1 As shown in f~i, the SiC and Ga2O3 lattices are clearly distinguishable. The (002) plane of SiC has a lattice spacing of 0.252 nm, while the (002) plane and (112) plane of Ga2O3 have lattice spacings of 0.279 nm and 0.197 nm, respectively. Figure 1 The image shows an amorphous layer of approximately 8–13 nm between SiC and Ga2O3. (See image j.) Figure 1As shown in Figure k, XRD analysis revealed characteristic diffraction peaks of the crystal structure. The diffraction peaks at 35.7°, 40.1°, 60.1°, 72°, and 75.7° can be attributed to 3C-SiC (PDF #29-1129). In addition, the diffraction peaks observed at 31.68°, 38.38°, and 45.6° correspond to the (002), (401), and (112) crystal planes of Ga2O3, respectively (PDF #76-0573). Figure 1 Figure 1 shows the spatial distribution of Si, C, O, and Ga elements on a single nanowire, further confirming the presence of Ga2O3 nanoparticles on the surface of the SiC nanowire. The above structural characterization analysis indicates that SiC / SiO2 / Ga2O3 core-shell-satellite nanowires were successfully prepared using acetone pretreatment combined with high-temperature annealing.

[0047] Example 6 This embodiment provides a method for fabricating a single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire ultraviolet photodetector, including the following steps: 0.10 mg of the prepared SiC / SiO2 / Ga2O3 nanowires were dispersed in 3 ml of isopropanol solution and ultrasonically dispersed for 60 minutes to obtain a uniform suspension. The suspension was drop-coated onto a Si / SiO2 substrate and dried in a 60 °C oven for 60 minutes. The substrate surface was observed under an optical microscope to screen out well-dispersed single nanowires of suitable length. Using the dried Si / SiO2 substrate as a mask and a 600-mesh copper grid, nickel electrodes were deposited in a vacuum evaporation apparatus. Subsequently, single nanowires were precisely transferred between two nickel electrodes using polydimethylsiloxane (PDMS) on a two-dimensional transfer platform; annealing was performed at 800 °C for 40 minutes in a vacuum annealing furnace to ensure good ohmic contact between the nanowires and the electrodes, thus successfully fabricating a single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire ultraviolet photodetector. The device structure is shown below. Figure 2 As shown, the distance between the two nickel electrodes is 4 μm.

[0048] Example 7 This embodiment provides a method for fabricating a single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire ultraviolet photodetector, including the following steps: 0.10 mg of the prepared SiC / SiO2 / Ga2O3 nanowires were dispersed in 3 ml of isopropanol solution and ultrasonically dispersed for 30 minutes to obtain a uniform suspension. The suspension was drop-coated onto a Si / SiO2 substrate and dried in an oven at 60 °C for 30 minutes. The substrate surface was observed under an optical microscope to screen out well-dispersed single nanowires of suitable length. The dried Si / SiO2 substrate was used as a mask, and nickel electrodes were deposited in a vacuum evaporation apparatus with a 600-mesh copper grid. Subsequently, single nanowires were precisely transferred between the nickel electrodes using polydimethylsiloxane (PDMS) on a two-dimensional transfer platform; annealing was performed at 800 °C for 40 minutes in a vacuum annealing furnace to ensure good ohmic contact between the nanowires and the electrodes, thus successfully fabricating a single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire ultraviolet photodetector, in which the spacing between the two nickel electrodes was 10 μm.

[0049] Example 8 This embodiment provides a method for fabricating a single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire ultraviolet photodetector, including the following steps: 0.05 mg of the prepared SiC / SiO2 / Ga2O3 nanowires were dispersed in 2 ml of isopropanol solution and ultrasonically dispersed for 60 minutes to obtain a uniform suspension. The suspension was drop-coated onto a Si / SiO2 substrate and dried in an oven at 60 °C for 60 minutes. The substrate surface was observed under an optical microscope to screen out well-dispersed single nanowires of suitable length. The dried Si / SiO2 substrate was used as a mask, and nickel electrodes were deposited in a vacuum evaporation apparatus with a 600-mesh copper grid. Subsequently, single nanowires were precisely transferred between the nickel electrodes using polydimethylsiloxane (PDMS) on a two-dimensional transfer platform; annealing was performed at 800 °C for 40 minutes in a vacuum annealing furnace to ensure good ohmic contact between the nanowires and the electrodes, thus successfully fabricating a single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire ultraviolet photodetector, in which the spacing between the two nickel electrodes was 4 μm.

[0050] Example 9 This embodiment provides a method for fabricating a single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire ultraviolet photodetector, including the following steps: 0.10 mg of the prepared SiC / SiO2 / Ga2O3 nanowires were dispersed in 3 ml of isopropanol solution and ultrasonically dispersed for 60 minutes to obtain a uniform suspension. The suspension was drop-coated onto a Si / SiO2 substrate and dried in an oven at 60 °C for 60 minutes. The substrate surface was observed under an optical microscope to screen out well-dispersed single nanowires of suitable length. The dried Si / SiO2 substrate was used as a mask, and nickel electrodes were deposited in a vacuum evaporation apparatus with a 600-mesh copper grid. Subsequently, single nanowires were precisely transferred between the nickel electrodes using polydimethylsiloxane (PDMS) on a two-dimensional transfer platform; annealing was performed at 600 °C for 20 minutes in a vacuum annealing furnace to ensure good ohmic contact between the nanowires and the electrodes, thus successfully fabricating a single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire ultraviolet photodetector, in which the spacing between the two nickel electrodes was 8 μm.

[0051] Detectors were successfully fabricated in Examples 6-9, and their photoelectric performance was tested using the device in Example 6 as an example.

[0052] Experimental Example 1 This experimental example provides the photoelectric performance test results of a dual-band ultraviolet photodetector with a single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire under different ultraviolet light irradiation conditions.

[0053] In this experimental example, the photoelectric performance testing system for a single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire ultraviolet photodetector was constructed by connecting a Keithley 4200SCS semiconductor parameter analyzer and a Micromanipulator 6150 high-precision probe station. The Micromanipulator 6150 probe station was equipped with a shielded enclosure to ensure testing accuracy in a dark environment. By adjusting external conditions (such as ultraviolet light wavelength, ultraviolet light power, and voltage) to influence the current of the single nanowire, the ultraviolet photoelectric detection performance of the single SiC / SiO2 / Ga2O3 nanowire detector was systematically studied.

[0054] Its ultraviolet photoelectric performance test results show that, Figure 3 As shown in Figure a, under 365 nm (UVA) ultraviolet light (245 mW / cm²), 2 At a bias voltage of 10 V and 10 V, the device achieved 5.3 × 10⁻⁶. 4 High A / W responsivity. At 254 nm (UVC) ultraviolet light (67 mW / cm²), 2 ) and 5 V bias ( Figure 3 (b~c) The device achieved a responsivity of 1547.06 A / W and an external quantum efficiency (EQE) of 7.42 × 10⁻⁶. 5The response and recovery times were 98 / 93 ms. At the same optical power density (67 mW / cm²), the response and recovery times were [missing information]. 2 The device exhibits a significantly higher photocurrent at 254 nm than at 365 nm (e.g., ...). Figure 3 (as shown in d). The selective recognition and high-performance detection of the dual-band UVA and UVC are mainly due to the multiple synergistic effects of the structure: (1) The SiC nanowire core layer serves as the central carrier transport channel. Its wide bandgap, high thermal stability and excellent electron mobility enable it to complete the generation and rapid transport of the main photogenerated carriers under 365 nm (UVA) illumination, which is the basis for the stable operation of the device under high temperature and strong light conditions; (2) The amorphous SiO2 intermediate layer not only acts as a passivation layer to effectively reduce surface recombination centers, but also acts as a carrier tunnel layer to promote the separation of interface charges; (3) Ga2O3 nanoparticles (bandgap of about 4.7 eV) act as sensitizers to enhance the response to the UVC (254 nm) band.

[0055] Furthermore, this device also exhibits excellent stability. For example... Figure 3 As shown in Figure e, under 254 nm irradiation (power density of 67 mW / cm²), its performance remained consistent after 80 consecutive cycles (totaling 150 seconds). Even without encapsulation and exposed to room temperature air for three months, the device maintained a stable photocurrent response with almost no attenuation. This operational stability is mainly attributed to the inherent high stability of the wide bandgap SiC and Ga₂O₃ materials themselves, as well as the passivation effect of the amorphous SiO₂ layer.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire, characterized in that, The nanowire comprises a SiC nanowire core, an amorphous SiO2 shell covering the SiC nanowire core, and Ga2O3 nanoparticles attached to the SiO2 shell, forming a core-shell-satellite structure.

2. A method for preparing a single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire as described in claim 1, characterized in that, Includes the following steps: SiC nanowires were soaked in acetone solution and subjected to ultrasonic treatment to expose unsaturated dangling bonds and high-energy active sites on the surface of the SiC nanowires, while inducing the formation of wrinkled stripe structures on the surface of the SiC nanowires. The treated SiC nanowires were mixed with Ga(NO3)3·6H2O and heated to 800℃~900℃ under vacuum sealing conditions at a heating rate of 3℃ / min~5℃ / min, and held at that temperature for 3h~5h. After cooling, they were annealed in air at 400℃~600℃ for 1h~3h. During this process, an amorphous SiO2 shell was formed in situ on the surface of the SiC nanowires, and Ga2O3 nanoparticles were attached to and grown on the amorphous SiO2 shell, forming SiC / SiO2 / Ga2O3 composite nanowires with a "core-shell satellite" multi-level structure.

3. The preparation method according to claim 2, characterized in that, The ultrasonic treatment time is 20-30 minutes.

4. The preparation method according to claim 2, characterized in that, The molar ratio of the treated SiC nanowires to Ga(NO3)3·6H2O is 3~5:

1.

5. A dual-band ultraviolet photodetector using a single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire, characterized in that... include: Si / SiO2 substrate; Nickel electrodes disposed at both ends of the Si / SiO2 substrate; as well as The single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire as described in claim 1 is disposed on the Si / SiO2 substrate and bridged between two nickel electrodes.

6. The dual-band ultraviolet photodetector according to claim 5, characterized in that, The spacing between the two nickel electrodes is 4 μm to 10 μm.

7. A method for fabricating a dual-band ultraviolet photodetector using a single SiC / SiO2 / Ga2O3 core-shell-satellite nanowire as described in claim 5, characterized in that, Includes the following steps: The SiC / SiO2 / Ga2O3 core-shell-satellite nanowires were dispersed and then drop-coated onto the Si / SiO2 substrate, dried, and individual nanowires were screened out. Two nickel electrodes are fabricated on the Si / SiO2 substrate, and the single nanowire is transferred between the two nickel electrodes to form an electrical connection, thus obtaining a pre-assembled device. The pre-assembled device is subjected to vacuum annealing to form an ohmic contact between the nanowire and the nickel electrode, thus obtaining the dual-band ultraviolet photodetector.

8. The preparation method according to claim 7, characterized in that, The SiC / SiO2 / Ga2O3 core-shell-satellite nanowires are dispersed in isopropanol and ultrasonically treated for 30-60 minutes. The ratio of SiC / SiO2 / Ga2O3 nanowires to isopropanol is 0.05-0.10 mg: 2-3 mL.

9. The preparation method according to claim 7, characterized in that, The drying conditions after drop coating are 60°C for 30-60 minutes; the nickel electrode is obtained by vacuum evaporation deposition. The vacuum annealing conditions are: annealing at 600℃~800℃ for 20min~40min.

10. The application of the dual-band ultraviolet photodetector of claim 5 in detecting ultraviolet radiation in different wavelength ranges, characterized in that, The dual-band ultraviolet photodetector is used to distinguish between ultraviolet radiation of 320~400 nm and 200~280 nm.

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