Deep ultraviolet photodetector and preparation method and application thereof

Abstract

This application discloses a deep ultraviolet (DUV) photodetector, its fabrication method, and its application. The DUV photodetector includes a substrate, a gallium oxide layer of a first conductivity type, and a transparent conductive layer of a second conductivity type; at least a selected area on the surface of the substrate is formed of a metallic material; the gallium oxide layer is disposed at least in the selected area on the surface of the substrate and forms an ohmic contact or a Schottky contact with the metallic material; the transparent conductive layer is disposed on the gallium oxide layer and forms a pn junction with the gallium oxide layer. The DUV photodetector of this application has advantages such as a high detection area ratio, high photoconductivity gain, fast response speed, high responsivity, and small size for easy integration. Furthermore, the fabrication process is simple and the manufacturing cost is low, which can well meet the needs of large-scale production.

Description

Technical Field

[0001] This application relates to a photodetector, specifically a deep ultraviolet photodetector, its fabrication method, and its application, belonging to the field of optoelectronic device technology. Background Technology

[0002] Photodetectors can rapidly convert light signals into electrical signals, finding wide applications in alarm and guidance, high-voltage discharge monitoring, fire early warning, and meteorological monitoring. Compared to infrared detectors, the development of solar-blind ultraviolet detectors is still at a relatively low level. Traditional photomultiplier tubes are large and operate at 100 volts; thermal detectors, while smaller and more accurate, have slow response times. The advent of fourth-generation ultra-wide bandgap semiconductor gallium oxide (GaO) has brought significant advantages. With a bandgap of 4.9 eV and a corresponding wavelength of 254 nm, GaO falls precisely in the solar-blind ultraviolet band. Furthermore, GaO exhibits high absorption coefficient and fast response in this region, offering substantial advantages over existing large-volume, high-energy-consuming photomultiplier tubes and traditional compound semiconductor materials such as gallium nitride and silicon carbide.

[0003] Existing gallium oxide-based solar-blind ultraviolet photodetectors are diverse. Under ultraviolet light irradiation at corresponding wavelengths (approximately 200nm-300nm), they exhibit photoconductive and photovoltaic effects, altering their carrier concentration and built-in field, thus changing their electrical characteristics and reflecting this as current at the detection end. Furthermore, the basic structures of existing gallium oxide-based solar-blind ultraviolet photodetectors are mainly horizontal and vertical. Horizontal structures have a larger device area, and reducing their size places high demands on photolithography processes and instrumentation. Moreover, as the size decreases, their responsivity and photocurrent-to-dark-current ratio decrease significantly. In vertical structures, metal electrodes are often grown on the upper layer. The presence of these metal electrodes blocks light absorption, reducing their photoresponsivity. Additionally, the non-equilibrium carriers generated in the Ga2O3 photosensitive region under ultraviolet light irradiation experience increased migration distances due to the non-vertical location of the metal electrodes, further reducing the detector's response speed. In addition, existing gallium oxide-based solar-blind ultraviolet photodetectors, whether horizontal or vertical, will block part of the detection area due to the presence of metal electrodes. In order to ensure the size of the photosensitive surface area of ​​the device, it is often necessary to increase the size of the entire device. Summary of the Invention

[0004] The purpose of this application is to provide a deep ultraviolet light detector, its fabrication method, and its application, in order to overcome the shortcomings of the prior art.

[0005] To achieve the aforementioned objectives, the technical solution adopted in this application includes:

[0006] The first aspect of this application provides a deep ultraviolet photodetector, comprising a substrate, a gallium oxide layer of a first conductivity type and a transparent conductive layer of a second conductivity type; at least a selected area on the surface of the substrate is formed of a metallic material; the gallium oxide layer is disposed at least on the selected area on the surface of the substrate and forms an ohmic contact or a Schottky contact with the metallic material; the transparent conductive layer is disposed on the gallium oxide layer and forms a pn junction with the gallium oxide layer.

[0007] In one embodiment, the metallic material comprises Pt. In some cases, the metallic material may also be other metallic materials besides Pt that can form an effective ohmic contact or Schottky contact with gallium oxide.

[0008] Preferably, the metal material is Pt, which can not only form a Schottky barrier with gallium oxide to improve the working capability of the device, but also, when gallium oxide is heteroepitaxially grown on metal Pt through heteroepitaxial process, it can effectively reduce lattice mismatch and reduce surface roughness compared to other heteroepitaxial substrates.

[0009] In one embodiment, the gallium oxide layer is grown in situ on a selected region of the substrate surface. For example, the gallium oxide layer may be grown on the selected region of the substrate surface by MOCVD (metal-organic chemical vapor deposition), atomic layer deposition (ALD), or other processes.

[0010] Furthermore, the selected area on the substrate surface can be a local area of ​​the substrate surface or the entire surface area of ​​the substrate.

[0011] In some cases, the substrate may be formed entirely of the metallic material.

[0012] In one embodiment, the gallium oxide layer is n-type and the transparent conductive layer is p-type.

[0013] In one embodiment, the gallium oxide layer is made of ε-Ga2O3. In some cases, other crystalline phases of gallium oxide thin films can also be used to construct photodetectors to achieve photodetection functions, and their response band can be tuned by changing their composition.

[0014] In one embodiment, the thickness of the gallium oxide layer is 10-600 nm, preferably around 300 nm.

[0015] In one embodiment, the transparent conductive layer comprises a carbon nanotube film that is transparent in the solar blind zone.

[0016] In one embodiment, the thickness of the carbon nanotube film is 0.2-2 nm, preferably around 1 nm.

[0017] In some cases, the transparent conductive layer may also be composed of other materials that have high conductivity and high transmittance in the solar blind zone band, and can form a pn junction with the gallium oxide layer.

[0018] Preferably, the transparent conductive layer is a carbon nanotube film that is transparent in the solar blind zone. This is because carbon nanotubes prepared by processes such as sol-gel deposition are naturally p-type, which can directly form a pn junction with n-type ε-Ga2O3, effectively reducing the dark current of the device.

[0019] Furthermore, carbon nanotubes possess a well-developed and mature fabrication process, exhibiting excellent stability, superior electron transport properties, high density, and high transmittance in the UVC (<280nm) band. Theoretically, they are ideally suited for bonding to gallium oxide, creating a complementary effect that significantly enhances the electron mobility of gallium oxide, improves the photoelectric conversion efficiency of photodetectors, and provides excellent electron injection and collection capabilities. However, in practical applications, directly contacting carbon nanotube films with gallium oxide alone presents two challenges: firstly, the high conductivity and low band gap of carbon nanotubes may lead to breakdown under high voltages, affecting the detector's performance and stability; secondly, it introduces surface states that severely impact detector performance. In this application, on the one hand, the synergistic combination of the Pt substrate, the n-type ε-Ga2O3 layer, and the carbon nanotube film not only effectively improves the quality of the metal-semiconductor contact by utilizing the high work function of Pt, reducing the impact of surface defects on electron transport, and significantly improving the signal-to-noise ratio, enhancing the device's response speed and sensitivity, but also effectively avoids reverse breakdown by forming a back-to-back PN junction and Schottky contact structure. The PN junction, by forming a built-in electric field, can suppress the increase of reverse current, preventing breakdown under reverse bias. The Schottky contact, with its low reverse leakage current and fast response time, effectively improves the device's stability and durability. Combining these two structures in the design not only enhances the device's performance but also significantly improves its breakdown resistance, thus ensuring the device's reliability and efficiency under high-voltage operating environments. On the other hand, after the basic structure of the photodetector is fabricated, annealing treatment can also largely eliminate the problems caused by direct contact between the carbon nanotube film and gallium oxide, thereby comprehensively improving the detector's electrical characteristics.

[0020] In addition, in some cases, the carbon nanotube film can also be narrow-band or linear, so that it can be directly used as a wire to function as the lead-out electrode of the detector.

[0021] In one embodiment, the substrate, gallium oxide layer, and transparent conductive layer cooperate to form a quasi-vertical PN junction / Schottky junction structure. In some cases, the deep ultraviolet photodetector may also be a device with other configurations including the pn junction.

[0022] In one embodiment, at least a selected area on the substrate surface is formed of a metallic material and constitutes a first electrode, and a second electrode is further disposed on the transparent conductive layer. For example, when the entire substrate is formed of a metallic material, the substrate itself can constitute the first electrode. The second electrode can be formed of metals such as Ti and Au, or non-metallic conductive materials such as AZO, ITO, and conductive carbon materials. It is preferably strip-shaped or linear to minimize the area of ​​the covered transparent conductive layer surface, thereby maximizing the effective detection area of ​​the detector.

[0023] In some cases, the first electrode may be omitted, and the carbon nanotube film may be used directly as the lead-out electrode of the detector.

[0024] A second aspect of this application provides a method for fabricating the deep ultraviolet light detector, comprising:

[0025] A substrate is provided, wherein at least a selected area of ​​the substrate surface is formed of a metallic material;

[0026] A gallium oxide layer of a first conductivity type is disposed at least in a selected area on the surface of the substrate, and the gallium oxide layer forms an ohmic contact or a Schottky contact with the metal material;

[0027] A transparent conductive layer of a second conductivity type is disposed on the gallium oxide layer, and the transparent conductive layer and the gallium oxide layer form a pn junction.

[0028] In one embodiment, the preparation method specifically includes: growing the gallium oxide layer in situ on a selected area of ​​the substrate surface by epitaxial growth.

[0029] For example, the gallium oxide layer can be grown in situ on a selected area of ​​the substrate surface using MOCVD process, and the growth temperature is controlled at 400-1200℃ (preferably 400-800℃), the oxygen flow rate is 400-10000 sccm (preferably 400-1000 sccm), the TEG flow rate is 400-900 sccm (preferably 400-600 sccm), and the growth time is 10-120 min (preferably 10-30 min).

[0030] In one embodiment, the preparation method specifically includes: depositing a carbon nanotube film on the gallium oxide layer at least by sol-gel deposition, and using the carbon nanotube film as the transparent conductive layer.

[0031] In some cases, carbon nanotube films can also be formed on the gallium oxide layer using other methods. For example, a carbon nanotube film with high transmittance and high conductivity in the solar blind zone can be formed by transferring the prepared carbon nanotube film onto the gallium oxide layer, or by in-situ deposition of carbon nanotubes on the gallium oxide layer using methods such as CVD (chemical vapor deposition).

[0032] Preferably, this application describes the deposition of a carbon nanotube thin film on the gallium oxide layer using a sol-gel deposition method. This method not only allows for low-temperature growth and controllable doping, but also enables the active groups on the surface of the carbon nanotubes to react and combine with the active groups on the surface of the gallium oxide layer in a solvent, thereby making the bond between the carbon nanotube film and the gallium oxide layer more robust and improving the structural stability of the device.

[0033] In one embodiment, the fabrication method specifically includes: after forming a device structure comprising the substrate, the gallium oxide layer, and the transparent conductive layer, annealing the device structure in a protective atmosphere at a temperature of 400-600°C for 2-5 minutes. The annealing process achieves at least the following effects: eliminating surface stress between carbon nanotubes and gallium oxide, resulting in better contact; removing impurities from the sol-gel deposition process, adjusting electronic properties; repairing defects and removing impurities in the carbon nanotubes, thereby improving carrier mobility; and adjusting the band gap of the carbon nanotubes, optimizing their band alignment with gallium oxide, thus improving the overall electronic performance of the device. Specifically: a) Annealing promotes the contact and interface quality between the carbon nanotubes and the gallium oxide substrate. Through heat treatment, the interfacial adhesion between the carbon nanotubes and the gallium oxide surface increases, thereby improving their electron transport characteristics and enhancing the contact performance between metal-semiconductor or semiconductor-carbon nanotube. This is crucial for improving the efficiency and stability of the device. b. During the growth of carbon nanotubes, impurities or oxide layers may deposit on the substrate surface, which can interfere with subsequent device performance. Annealing can effectively remove these adverse substances, especially oxide layers, thereby improving the interfacial electrical properties between carbon nanotubes and gallium oxide. c. Annealing can also modulate the electronic properties of carbon nanotubes. Especially under high-temperature conditions, defects and impurities in carbon nanotubes may be repaired, leading to increased carrier mobility. In addition, annealing may also modulate the band gap of carbon nanotubes, optimizing their band alignment with gallium oxide, thereby improving the overall electronic performance of the device.

[0034] The protective atmosphere can be formed by nitrogen, argon, or a mixture thereof.

[0035] In one embodiment, the preparation method further includes:

[0036] After the annealing process is completed, the gallium oxide layer and the transparent conductive layer are partially removed to expose a portion of the metal material and form the first electrode.

[0037] In addition, a second electrode is disposed on the transparent conductive layer.

[0038] For example, a second electrode can be grown on the transparent conductive layer using photolithography and electron beam evaporation processes.

[0039] For example, excess portions of the gallium oxide layer and the transparent conductive layer can be removed by plasma etching or similar processes, exposing the metal material portion on the substrate surface to form the first electrode.

[0040] The third aspect of this application provides the application of the deep ultraviolet light detector in the detection of solar-blind ultraviolet light.

[0041] For example, one embodiment of this application provides a light detection method, which includes subjecting the light to be detected to the deep ultraviolet light detector, and detecting solar-blind ultraviolet light in the light to be detected based on the detection signal output by the deep ultraviolet light detector.

[0042] Compared with the prior art, the advantages of this application include:

[0043] Firstly, the provided deep ultraviolet photodetector utilizes a transparent conductive layer formed by carbon nanotube films, which exhibit good uniformity, stability, conductivity, and transparency in the solar-blind region. This not only overcomes the defect of metal obstruction of the detector's detection area caused by the interdigitated structure of the MSM (Mesh Detector) and greatly expands the effective detection area, but also allows the carbon nanotube film to form a pn junction contact with the gallium oxide layer, effectively reducing the non-equilibrium carrier migration distance and the resulting dark current, thus significantly improving the detector's response capability. Simultaneously, using metal Pt as the heteroepitaxial growth substrate for the gallium oxide layer not only improves the crystal and surface quality of the gallium oxide layer but also forms a Schottky barrier with it, enhancing the detector's operational capability. Furthermore, this detector, based on the synergistic composition of carbon nanotube films, ε-Ga2O3 layers, and metal Pt substrates, effectively reduces the overall area while maintaining the size of its photosensitive region. This makes it highly suitable for fabricating solar-blind ultraviolet photodetector arrays, enabling detection and imaging in the solar-blind ultraviolet band. It boasts advantages such as a high detection area ratio, high photoconductivity gain, fast response speed, high responsivity, and small size for easy integration.

[0044] Secondly, the deep ultraviolet light detector provided has a simple manufacturing process and low production cost, which can well meet the needs of large-scale production. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the axial cross-sectional structure of a deep ultraviolet light detector according to an embodiment of this application;

[0046] Figure 2 yes Figure 1 A top view of the deep ultraviolet photodetector shown;

[0047] Figure 3 This is a schematic diagram illustrating the fabrication process of a deep ultraviolet light detector according to one embodiment of this application;

[0048] Figure 4 This is a transmittance test diagram of a carbon nanotube film to solar-blind ultraviolet light before and after annealing in one embodiment of this application. Detailed Implementation

[0049] The technical solution, implementation process, and principles of this application will be further explained below with reference to the accompanying drawings and several embodiments.

[0050] Please refer to Example 1 Figure 1-2 As shown, this embodiment provides a deep ultraviolet light detector comprising a Pt metal substrate 1 and an n-type ε-Ga₂O₃ layer 2 and a p-type carbon nanotube film 3 sequentially stacked on the substrate 1. A ring-shaped metal electrode 4 is also disposed on the carbon nanotube film 3. The substrate 1 serves as the first electrode of the detector. Correspondingly, the metal electrode 4 is the second electrode. The detector has a quasi-vertical PN junction / Schottky junction structure.

[0051] The n-type ε-Ga₂O₃ layer 2 forms a Schottky contact with the substrate 1, and the n-type ε-Ga₂O₃ layer 2 forms a pn junction with the p-type carbon nanotube film 3. The metal electrode 4 forms an ohmic contact with the p-type carbon nanotube film 3. The thicknesses of the n-type ε-Ga₂O₃ layer 2 and the p-type carbon nanotube film 3 are approximately 50 nm and 1 nm, respectively. The metal electrode 4 is made of Ti / Au (with a thickness of approximately 50 nm / 100 nm).

[0052] See Figure 3 One method for fabricating the detector includes the following steps:

[0053] S1. First, use acetone and isopropanol to ultrasonically clean the Pt substrate to remove dust and organic contaminants from its surface. Then, grow an n-type ε-Ga2O3 layer on the Pt substrate using MOCVD. During the growth process, control the growth temperature to be approximately 500℃, the O2 introduction rate to be approximately 440 sccm, the TEG introduction rate to be approximately 495 sccm, and the growth time to be approximately 15 min.

[0054] S2. Deposit p-type carbon nanotube films on n-type ε-Ga2O3 layers using the sol-deposition method described in reference 1.

[0055] S3. Using a plasma etching process, partially etch away the p-type carbon nanotube film and n-type ε-Ga2O3 layer in the device structure finally obtained in step S2, so that the annular region on the surface of the Pt substrate is exposed. This annular region surrounds the area on the surface of the Pt substrate that is covered by the remaining p-type carbon nanotube film and n-type ε-Ga2O3 layer.

[0056] S4. The device structure obtained in step S3 is annealed in a nitrogen / argon mixed atmosphere (volume ratio of about 1:1) at a temperature of about 500°C for about 3 minutes. After spin-coating with AZ5214 and UV exposure and development, the desired pattern is obtained. Then, metal electrodes are grown on the p-type carbon nanotube film using electron beam evaporation. The formed device structure is then immersed in acetone for cleaning to remove excess metal.

[0057] Figure 4 The results of transmittance tests for solar-blind ultraviolet light are shown for p-type carbon nanotube films fabricated on glass slides using the same process conditions as in step S2, before and after annealing (annealing conditions are the same as in step S4). It can be seen that carbon nanotubes show almost no absorption or reflection of ultraviolet light.

[0058] Comparative Example 1: The structure and preparation method of the deep ultraviolet light detector provided in this comparative example are basically the same as those in Example 1, except that: in step S1, an n-type ε-Ga2O3 thin film is prepared according to the method of CN115719708A and then transferred to a Pt substrate.

[0059] Comparative Example 2 provides a deep ultraviolet light detector with a structure and preparation method that are basically the same as those in Example 1, except that the p-type carbon nanotube film is replaced with a p-type graphene film of the same thickness.

[0060] Comparative Example 3 provides a deep ultraviolet light detector with a structure and preparation method that are basically the same as those in Example 1, except that in step S2, a commercially available carbon nanotube film (purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., XFZ35-308068-56-6-103457) is cut and transferred onto an n-type ε-Ga2O3 layer.

[0061] Comparative Example 4 provides a deep ultraviolet light detector with a structure and preparation method that are basically the same as those in Example 1, except that annealing is not performed in step S4.

[0062] The performance of the detectors in the embodiments and comparative examples 1-4 was tested according to the methods in references 4 and 5, and the results are shown in Table 1 below.

[0063] Table 1. Performance test results of the detectors in the embodiments and comparative examples 1-4.

[0064] serial number responsiveness Response speed Example 1 2640A / W 0.013s Comparative Example 1 1360A / W 0.03s Comparative Example 2 124A / W 0.006s Comparative Example 3 1250A / W 0.042s Comparative Example 4 2520A / W 0.05s

[0065] Note: The data listed in the table above are the average values ​​obtained from multiple tests on multiple samples.

[0066] In addition, the applicant also found through comparative experiments that if the Pt substrate in Example 1 is replaced with other metal substrates such as Cu, Ti, and W, the dark current (noise) and responsivity of the detector will both increase, but the overall performance will decrease significantly.

[0067] Example 2: The deep ultraviolet photodetector and its fabrication method provided in this example are basically the same as those in Example 1, except that:

[0068] In the detector structure, the thickness of the n-type ε-Ga2O3 layer is about 600 nm, and the thickness of the carbon nanotube film is about 2 nm. It is fabricated according to the method in Reference 2.

[0069] In the fabrication method of the detector, the growth temperature of the n-type ε-Ga2O3 layer is about 800℃, the oxygen flow rate is about 1000 sccm, and the TEG flow rate is about 600 sccm.

[0070] Example 3: The deep ultraviolet photodetector and its fabrication method provided in this example are basically the same as those in Example 1, except that:

[0071] In the detector structure, the thickness of the n-type ε-Ga2O3 layer is about 10 nm, and the thickness of the carbon nanotube film is about 1.5 nm, and it is fabricated according to the method in Reference 3.

[0072] In the fabrication method of the detector, the growth temperature of the n-type ε-Ga2O3 layer is about 400℃, the oxygen flow rate is 400 sccm, and the TEG flow rate is 400 sccm.

[0073] The detector performance of Examples 2 and 3 was tested according to the method described in the above literature, and the results showed that they also have the advantages of fast response speed and high responsivity.

[0074] It should be understood that the above embodiments are merely illustrative of the technical concept and features of this application, and are intended to enable those skilled in the art to understand the content of this application and implement it accordingly. They should not be construed as limiting the scope of protection of this application. All equivalent changes or modifications made in accordance with the spirit and essence of this application should be included within the scope of protection of this application.

[0075] The specific information about the documents mentioned in this specification is as follows:

[0076] Reference 1: Lin, C.R., Su, C.H., Hung, C.H., Chang, C.Y., & Stobinski, L (2005). Characterization of bamboo-like CNTs prepared using sol-gel catalyst. Diamond and Related Materials, 14(3-7), 493-496. https: / / doi.org / 10.1016 / j.diamond.2004.12.005.

[0077] Reference 2: Alfryyan, N., Akram, M., Manzoor, A., Jamil, A., Alrowaili, Z.A., Al-Buriahi, M.S., Irshad, A., & Din, M.I. (2023). Synthesis of Cd-substituted NiCoPrFe2O4@CNTs via sol-gel method: Investigating the structural and photocatalytic properties. Physica B: Condensed Matter, 635, 414885. https: / / doi.org / 10.1016 / j.physb.2023.414885.

[0078] Reference 3: Mahdiani, M., Sobhani, A., & Salavati-Niasari, M. (2017). Enhancement of magnetic, electrochemical and photocatalytic properties of lead hexaferrites with coating graphene and CNT: Sol-gel auto-combustion synthesis by valine. Separation and Purification Technology, 177, 305-313. https: / / doi.org / 10.1016 / j.seppur.2017.05.029.

[0079] Literature 4: Chen, T.; Zhang, X.; Ma, Y.; He, T.; Wei, X.; Tang, W.; Tang, W.; Zhou, X.; Fu, H.; Zhang, L.; et al. Self-Powered and Spectrally Distinctive Nanoporous Ga2O3 / GaN Epitaxial Heterojunction UV Photodetectors. Adv. Photon. Res. 2021, 2, No. 2100049.

[0080] Literature 5: Chen, X.; Liu, K.W.; Zhang, Z.Z.; Wang, C.R.; Li, B.H.; Zhao, H.F.; Zhao, D.X.; Shen, D.Z. Self-Powered Solar-Blind Photodetector with Fast Response Based on Au / β-Ga2O3 Nanowires Array Film Schottky Junction. ACS Appl. Mater. Interfaces 2016, 8, 4185-4191.

Claims

1. A deep ultraviolet light detector, characterized in that, The device includes a substrate, a gallium oxide layer of a first conductivity type, and a transparent conductive layer of a second conductivity type; at least a selected area on the surface of the substrate is formed of a metallic material; the gallium oxide layer is disposed at least on the selected area on the surface of the substrate and forms an ohmic contact or a Schottky contact with the metallic material; the transparent conductive layer is disposed on the gallium oxide layer and forms a pn junction with the gallium oxide layer.

2. The deep ultraviolet light detector according to claim 1, characterized in that: The metallic material includes Pt; and / or, the gallium oxide layer is grown in situ on a selected region of the substrate surface; And / or, the transparent conductive layer comprises a carbon nanotube film transparent in the solar blind zone; and / or, the thickness of the transparent conductive layer is 0.2-2 nm; and / or, the gallium oxide layer is made of ε-Ga2O3; and / or, the thickness of the gallium oxide layer is 10-300 nm; and / or, the gallium oxide layer is n-type and the transparent conductive layer is p-type.

3. The deep ultraviolet light detector according to claim 1, characterized in that: The substrate, gallium oxide layer, and transparent conductive layer work together to form a quasi-vertical PN junction / Schottky junction structure.

4. The deep ultraviolet light detector according to claim 1, characterized in that: At least a selected area on the surface of the substrate is formed of a metallic material and constitutes a first electrode, and a second electrode is also disposed on the transparent conductive layer.

5. The method for fabricating a deep ultraviolet photodetector according to any one of claims 1-4, characterized in that, include: A substrate is provided, wherein at least a selected area of ​​the substrate surface is formed of a metallic material; A gallium oxide layer of a first conductivity type is disposed at least in a selected area on the surface of the substrate, and the gallium oxide layer forms an ohmic contact or a Schottky contact with the metal material; A transparent conductive layer of a second conductivity type is disposed on the gallium oxide layer, and the transparent conductive layer and the gallium oxide layer form a pn junction.

6. The preparation method according to claim 5, characterized in that, Specifically, it includes: The gallium oxide layer is formed in situ on a selected area of ​​the substrate surface by epitaxial growth.

7. The preparation method according to claim 6, characterized in that, Specifically, it includes: The gallium oxide layer is grown in situ on a selected area of ​​the substrate surface using MOCVD process, and the growth temperature is controlled at 400-1200℃, the oxygen flow rate is 400-10000 sccm, the TEG flow rate is 400-900 sccm, and the growth time is 10-120 min. And / or, at least by sol-gel deposition, a carbon nanotube film is deposited on the gallium oxide layer, and the carbon nanotube film is used as the transparent conductive layer.

8. The preparation method according to claim 7, characterized in that, Specifically, it includes: After forming the device structure comprising the substrate, the gallium oxide layer and the transparent conductive layer, the device structure is annealed in a protective atmosphere at a temperature of 400-600°C for 2-5 minutes.

9. The preparation method according to claim 8, characterized in that, Also includes: After the annealing process is completed, the gallium oxide layer and the transparent conductive layer are partially removed to expose a portion of the metal material and form the first electrode. In addition, a second electrode is disposed on the transparent conductive layer.

10. The application of the deep ultraviolet light detector according to any one of claims 1-4 in the detection of solar-blind ultraviolet light.

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