A diamond / gallium oxide heterojunction and its application in solar-blind ultraviolet detectors

Abstract

The invention relates to the technical field of solar-blind ultraviolet detector materials, and specifically discloses a diamond / gallium oxide heterojunction and its application in solar-blind ultraviolet detectors, wherein the diamond / gallium oxide heterojunction comprises a single-crystal diamond layer and a Zr-doped ε-Ga2O3 layer on the single-crystal diamond layer; the single-crystal diamond layer is a (100)-oriented single-crystal diamond, and the surface roughness RMS of the single-crystal diamond is 2-6nm; the Zr-doped ε-Ga2O3 layer is a Zr-doped ε-Ga2O3 heteroepitaxially grown on the surface of the single-crystal diamond by a pulsed laser deposition method; the Zr-doped ε-Ga2O3 grows along the (001) direction on the surface of the single-crystal diamond; and the Zr-doped ε-Ga2O3 is a columnar crystal structure. The heterojunction of the invention realizes excellent photoelectric detection performance, solves the problem of poor selectivity of traditional solar-blind ultraviolet detectors, and has a wide range of application value.

Description

Technical Field

[0001] The invention relates to the technical field of solar-blind ultraviolet detector materials, and in particular to a diamond / gallium oxide heterojunction and application thereof in solar-blind ultraviolet detectors. Background Art

[0002] As a new type of photoelectric detection device, solar-blind ultraviolet detectors have important applications in the fields of solar ultraviolet radiation monitoring, fire warning, biochemical detection, and military warning. This type of detector needs to have high responsiveness in the deep ultraviolet band (200~280nm) and extremely low response to visible light to achieve accurate detection of the target spectrum. Heterostructures based on wide-bandgap semiconductor materials are an important way to achieve high-performance solar-blind ultraviolet detection. Diamond and Ga2O3 have excellent photoelectric properties and suitable bandgap widths, making them high-performance heterojunction materials. Diamond has characteristics such as an ultra-wide bandgap of 5.47eV, high carrier mobility, and excellent thermal conductivity, while Ga2O3 has a tunable band structure and good chemical stability. The heterojunction of the two materials can give full play to their respective advantages, providing an important basis for the realization of high-performance solar-blind ultraviolet detectors.

[0003] At present, heterostructures based on diamond and Ga2O3 still face key challenges in interface engineering and detection efficiency in practical applications. For example, the Chinese patent with publication number CN117976758A discloses a solar-blind ultraviolet detector based on diamond / AlScN heterojunction, but due to the interface lattice mismatch, the interface state density is high and the carrier recombination loss is serious, which ultimately affects the quantum efficiency of the device. The Chinese patent with publication number CN116779725A proposes a solar-blind ultraviolet photodetector based on Ga2O3-few-layer MXenes heterojunction, but the interface bonding is not tight and the energy band mismatch limits the effective separation and transmission of photogenerated carriers. In addition, the stress regulation and defect passivation of the interface between diamond and Ga2O3 heterojunction in the prior art have not been effectively solved, and the interface state and energy band discontinuity lead to increased carrier recombination losses. At the same time, the crystal phase regulation and interface bonding mechanism of Ga2O3 are not well studied, which hinders the breakthrough improvement of device performance. The existence of these key scientific issues seriously restricts the practical application of diamond / gallium oxide heterojunction solar-blind ultraviolet detectors. Summary of the invention

[0004] (1) Technical issues solved

[0005] The purpose of the present invention is to provide a diamond / gallium oxide heterojunction and its application in a solar-blind ultraviolet detector, so as to solve the problem that the current heterojunction has insufficient performance in interface engineering and detection efficiency.

[0006] (2) Technical solution

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A diamond / gallium oxide heterojunction, comprising a single crystal diamond layer and a Zr-doped ε-Ga2O3 layer on the single crystal diamond layer;

[0009] The single crystal diamond layer is a single crystal diamond with a (100) orientation, and the surface roughness RMS of the single crystal diamond is 2-6 nm;

[0010] The Zr-doped ε-Ga2O3 layer is Zr-doped ε-Ga2O3 heteroepitaxially grown on the surface of a single crystal diamond by a pulsed laser deposition method; the Zr-doped ε-Ga2O3 grows along the (001) direction on the surface of the single crystal diamond; the Zr-doped ε-Ga2O3 has a columnar crystal structure;

[0011] The preparation method of the diamond / gallium oxide heterojunction comprises the following steps: placing a single crystal diamond in a magnetron sputtering deposition chamber, using an RF sputtering mode and a DC sputtering mode for a Ga2O3 target and a Zr target respectively, with an oxygen partial pressure of 0.010-0.020 mbar, a substrate temperature of 550-570°C, an RF sputtering power of 100-200 W, a DC sputtering power of 10-50 W, a deposition time of 180-240 min, and a deposition thickness of 300-500 nm.

[0012] The present invention selects (100) oriented single crystal diamond as the substrate material, which can not only provide an ideal lattice matching platform, but also its crystal orientation arrangement perpendicular to the heterojunction interface is conducive to the directional transmission of carriers. The Zr-doped ε-Ga2O3 grown on the surface of single crystal diamond by pulsed laser deposition presents a regular columnar crystal structure and grows preferentially along the (001) direction. This specific growth orientation not only ensures the lattice matching degree with the single crystal diamond substrate, but also forms a channel structure that is conducive to carrier transmission. The introduction of Zr doping can regulate the band structure and carrier concentration of ε-Ga2O3. At the same time, the formation of the columnar crystal structure helps to provide a direct carrier transmission path. These features work synergistically with the single crystal diamond substrate to significantly improve the bonding quality and carrier transmission efficiency of the heterojunction interface. In addition, Zr-doped ε-Ga2O3 has a more suitable band structure than other phases, and the heterojunction formed with single crystal diamond can achieve higher performance band matching, which is conducive to the effective separation and collection of photogenerated carriers, thereby improving the detection sensitivity and response characteristics of the device. The low roughness of the single crystal diamond surface of the present invention creates favorable conditions for the subsequent epitaxial growth of Ga2O3.

[0013] Preferably, the interface between the single crystal diamond layer and the Zr-doped ε-Ga2O3 layer is a coherent interface; the diamond / gallium oxide heterojunction of the present invention achieves coherent bonding of the heterojunction interface by constructing a high-quality Zr-doped ε-Ga2O3 heteroepitaxial layer on the (100) oriented single crystal diamond surface, thereby effectively solving key problems such as lattice mismatch and carrier recombination existing in traditional diamond-based heterojunction interfaces.

[0014] Preferably, the Zr atom doping amount of the Zr-doped ε-Ga2O3 is ; The carrier concentration of the Zr-doped ε-Ga2O3 is . The present invention achieves highly selective detection of heterojunction devices in the deep ultraviolet band by optimizing the Zr doping amount and carrier concentration. By precisely controlling the Zr atomic doping concentration, the band structure and carrier concentration of ε-Ga2O3 are successfully regulated to match the energy band of diamond. This doping regulation not only optimizes the carrier transmission characteristics, but also significantly improves the photoelectric response performance of the device.

[0015] Preferably, within the wavelength range of 210-280 nm, the ratio of the response value of the diamond / gallium oxide heterojunction at a wavelength of 210 nm to that at 280 nm is 150-180, and the ratio of the response value at a wavelength of 240 nm to that at 280 nm is 90-110.

[0016] Preferably, the dark current of the diamond / gallium oxide heterojunction at a bias voltage of 10V is , the photocurrent under ultraviolet irradiation is .

[0017] In terms of spectral response characteristics, the heterojunction structure exhibits excellent wavelength selectivity in the deep ultraviolet band, especially in the wavelength range of 210~280nm, which shows obvious cutoff characteristics, which is highly consistent with the requirements of high-performance day-blind ultraviolet detection. The device exhibits extremely low dark current and high photocurrent under bias voltage, reflecting an excellent light-to-dark current ratio. This performance feature originates from the high-quality coherent interface formed between single crystal diamond and Zr-doped ε-Ga2O3, as well as the reasonable energy band design achieved through doping.

[0018] The synergistic effect of the ultra-wide bandgap characteristics of diamond and the band structure of ε-Ga2O3 regulated by Zr doping not only ensures the high responsiveness of the device in the deep ultraviolet region, but also effectively suppresses the visible light response and achieves high-performance solar-blind characteristics. This design strategy based on heterojunction interface engineering and carrier regulation provides a feasible technical path for the realization of high-performance solar-blind ultraviolet photodetectors.

[0019] Preferably, the method for preparing single crystal diamond comprises the following steps:

[0020] The Ir / YSZ / Si(100) substrate is placed in a microwave plasma enhanced chemical vapor deposition reactor, and nucleation treatment and growth treatment are performed in sequence to obtain a single crystal diamond / Ir / YSZ / Si(100) substrate; then the single crystal diamond / Ir / YSZ / Si(100) substrate is subjected to acid etching and mechanical polishing in sequence to remove YSZ / Si(100) and Ir in sequence to obtain a single crystal diamond;

[0021] The process parameters of the nucleation treatment are: bias voltage of -300~-250V, microwave power of 1000~1200W, substrate temperature of 700~750°C, working pressure of 100~150mbar, a mixed gas of methane, nitrogen and hydrogen as the reaction atmosphere, the volume fraction of methane in the mixed gas is 3~4%, the content of nitrogen is 40~60ppm, the flow rate of the mixed gas is 100~150sccm, and the nucleation treatment time is 20~35min;

[0022] After the nucleation treatment is completed, the growth treatment is carried out, the growth treatment temperature remains unchanged, and the process parameters of the growth treatment are: bias voltage is -250~-200V, microwave power is 900~1000W, working pressure is 150~200mbar, and a mixed gas of methane, nitrogen and hydrogen is used as the reaction atmosphere. The volume fraction of methane in the mixed gas is 6.0~10.0%, the content of nitrogen is 90~110ppm, the flow rate of the mixed gas is 150~200sccm, and the growth treatment time is 120~360min.

[0023] Preferably, the acid etching method comprises the following steps: completely immersing the single crystal diamond / Ir / YSZ / Si(100) substrate in a mixed acid solution for etching, wherein the mixed acid solution is obtained by mixing hydrofluoric acid with a mass fraction of 45-55wt.% and nitric acid with a mass fraction of 55-65wt.%, the volume ratio of the hydrofluoric acid to the nitric acid is 1:3, the etching temperature is 25-35°C, the etching time is 60-120min, and then the etched substrate is fully cleaned with deionized water until the cleaning solution is neutral, thereby obtaining a substrate with YSZ / Si(100) removed;

[0024] The mechanical polishing method comprises the following steps: using a diamond suspension to mechanically polish a substrate from which YSZ / Si(100) is removed to remove Ir, the average particle size of diamond particles in the diamond suspension is 5-10 nm, the polishing pressure is 2-5 psi, the polishing time is 30-60 min, the surface roughness RMS of the single crystal diamond after polishing is 2-6 nm, then the single crystal diamond is cleaned with deionized water, and dried by nitrogen, and finally the single crystal diamond is obtained.

[0025] Preferably, the method for preparing the Ir / YSZ / Si(100) substrate comprises the following steps:

[0026] A Si (100) wafer with a thickness of 2.0 to 4.0 mm was used as the substrate and placed in a vacuum chamber. In a high vacuum chamber of Torr, a pulsed laser deposition method is used to prepare YSZ with a thickness of 20-50 nm on a Si(100) wafer. The deposition temperature is 700-750°C, the wavelength of the pulsed laser is 248 nm, the laser repetition frequency is 5-10 Hz, the laser energy density is 1.5-2.0 J / cm², and 99.99% pure oxygen with a flow rate of 50-100 sccm is used as the reaction atmosphere. The deposition time is 15-30 min, and YSZ / Si(100) is obtained after the deposition is completed and cooled to room temperature.

[0027] Then YSZ / Si(100) was transferred to an electron beam evaporation system and Under the conditions of 3000 ℃ and 8000 ℃, use iridium with a purity of 99.99% as the evaporation source, control the evaporation rate to 0.05~0.1nm / s, the substrate rotation speed to 10~20rpm, the substrate temperature to 620~650℃, the thickness of the deposited Ir layer to 120~150nm, and slowly cool to room temperature after deposition.

[0028] The present invention adopts a multi-stage precision preparation process design mainly to enhance the interface quality and structural integrity of the heterojunction. This scheme realizes the preparation of high-quality single-crystal diamond substrates and the controllable growth of Zr-doped ε-Ga2O3 through a precisely controlled multi-step preparation process. First, Ir / YSZ / Si (100) is used as the substrate material, and the growth of the YSZ buffer layer and the Ir transition layer is precisely controlled by pulsed laser deposition and electron beam evaporation technology, providing an ideal lattice matching platform for the subsequent epitaxial growth of single-crystal diamond. In the process of microwave plasma enhanced chemical vapor deposition, the controllable growth of high-quality single-crystal diamond is achieved by optimizing the process parameters of the two stages of nucleation and growth, including bias voltage, microwave power, temperature, pressure, and reaction gas ratio. The subsequent acid etching and mechanical polishing steps not only remove the auxiliary growth layer, but also ensure the low roughness of the diamond surface, creating favorable conditions for the subsequent epitaxial growth of Ga2O3. In the preparation of Zr-doped ε-Ga2O3, the precise co-deposition of Ga2O3 and Zr was achieved through the synergistic effect of RF sputtering and DC sputtering. The precise control of temperature, power and oxygen partial pressure during the deposition process ensured the formation of the ε phase and the effective doping of Zr. The synergistic effect of this multi-level precision preparation process not only ensured the high-quality growth of each functional layer, but also achieved the coherent interface formation between diamond and Ga2O3 through interface engineering, thus laying a material foundation for improving device performance.

[0029] As a general inventive concept, the present invention provides an application of a diamond / gallium oxide heterojunction in a solar-blind ultraviolet photodetector.

[0030] (3) Beneficial technical effects

[0031] 1. The present invention achieves excellent solar-blind ultraviolet detection performance by constructing a diamond / gallium oxide heterojunction structure. The specific crystal orientation of the diamond substrate and the columnar crystal structure of Zr-doped ε-Ga2O3 form an efficient carrier transmission channel, which significantly improves the photoelectric conversion efficiency of the device. Zr doping not only achieves precise regulation of the ε-Ga2O3 band structure and carrier concentration, but also optimizes the separation and transmission of interface carriers by matching the band with single-crystal diamond. In addition, the present invention effectively solves the lattice mismatch problem of traditional heterojunctions by combining the coherent interface of (100)-oriented single-crystal diamond and Zr-doped ε-Ga2O3. This design strategy based on interface engineering and band regulation enables the device to exhibit excellent wavelength selectivity and high responsiveness in the deep ultraviolet band while maintaining extremely low dark current, providing an innovative solution for the development of a new generation of high-performance solar-blind ultraviolet detectors. Compared with traditional technologies, the present invention has obvious advantages in device preparation and performance optimization, and can be widely used in fields such as atmospheric monitoring, flame detection and biomedicine.

[0032] 2. The present invention significantly improves the interface quality and structural integrity of the diamond / gallium oxide heterojunction through the innovative design of a multi-stage precision preparation process. The use of an Ir / YSZ / Si (100) substrate in combination with pulsed laser deposition and electron beam evaporation technology provides an ideal lattice matching platform for diamond epitaxial growth. The controllable growth of high-quality single-crystalline diamond is achieved through the optimization of process parameters during microwave plasma enhanced chemical vapor deposition. The coordinated application of subsequent surface treatment processes and RF / DC radio frequency sputtering ensures the precise preparation of Zr-doped ε-Ga2O3. The synergistic effect of this multi-stage process not only solves the problems of difficult interface quality control and poor structural integrity in the preparation of traditional heterojunctions, but also achieves high-quality growth of each functional layer and a significant improvement in interface coherence, laying a technological foundation for the industrial application of high-performance ultraviolet photodetectors, and has important application value in the fields of photoelectric detection and environmental monitoring.

[0033] 3. The present invention successfully realizes high-performance photoelectric detection of diamond / gallium oxide heterojunction solar-blind UV detectors through precise Zr doping and carrier concentration control. By optimizing the Zr doping concentration, precise control of the ε-Ga2O3 band structure and carrier characteristics is achieved, forming a band match with single-crystalline diamond. This design exhibits excellent wavelength selectivity and cutoff characteristics in the 210-280nm band, while maintaining extremely low dark current and high photocurrent ratio. The synergistic effect of the ultra-wide bandgap of diamond and the band structure of Zr-doped ε-Ga2O3 not only ensures the high responsiveness of the device in the deep ultraviolet region, but also effectively suppresses the visible light response, achieving high-performance solar-blind characteristics. This design strategy based on heterojunction interface engineering and carrier control solves the problems of poor wavelength selectivity and large dark current of traditional devices, and provides an innovative solution for the development of high-performance solar-blind UV detectors. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a cross-sectional scanning electron microscope image of the diamond / gallium oxide heterojunction prepared in Example 1 of the present invention.

[0035] Figure 2 This is a roughness characterization diagram of the polished single crystal diamond surface prepared in Example 1 of the present invention.

[0036] Figure 3 This is the phase XRD spectrum of the diamond / gallium oxide heterojunction prepared in Example 1 of the present invention.

[0037] Figure 4 This is a transmission electron microscope (TEM) photograph of the diamond / gallium oxide heterojunction interface prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0038] To make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0039] Embodiment 1:

[0040] A diamond / gallium oxide heterojunction comprises a single crystal diamond layer and a Zr-doped ε-Ga2O3 layer located on the single crystal diamond layer; the single crystal diamond layer is a single crystal diamond with a (100) orientation; the Zr-doped ε-Ga2O3 layer is Zr-doped ε-Ga2O3 heteroepitaxially grown on the surface of the single crystal diamond by a pulsed laser deposition method; the Zr-doped ε-Ga2O3 grows along the (001) direction on the surface of the single crystal diamond; the Zr-doped ε-Ga2O3 has a columnar crystal structure; and the interface between the single crystal diamond layer and the Zr-doped ε-Ga2O3 layer is a coherent interface.

[0041] The preparation method of the single crystal diamond in this embodiment is:

[0042] S1, placing the Ir / YSZ / Si(100) substrate into a microwave plasma enhanced chemical vapor deposition reactor, and sequentially performing nucleation treatment and growth treatment to obtain a single crystal diamond / Ir / YSZ / Si(100) substrate;

[0043] The process parameters of the nucleation treatment are: bias voltage of -300 V, microwave power of 1000 W, substrate temperature of 700 ° C, working pressure of 100 mbar, mixed gas of methane, nitrogen and hydrogen as the reaction atmosphere, the volume fraction of methane in the mixed gas is 3%, the content of nitrogen is 50 ppm, the flow rate of the mixed gas is 100 sccm, and the nucleation treatment time is 20 min;

[0044] After the nucleation treatment is completed, the growth treatment is carried out. The growth treatment temperature remains unchanged. The process parameters of the growth treatment are: bias voltage is -250V, microwave power is 900W, working pressure is 150mbar, and a mixed gas of methane, nitrogen and hydrogen is used as the reaction atmosphere. The volume fraction of methane in the mixed gas is 8%, the content of nitrogen is 100ppm, the flow rate of the mixed gas is 150sccm, and the growth treatment time is 120min. After the treatment, a single crystal diamond / Ir / YSZ / Si(100) substrate is obtained.

[0045] S2, then subjecting the single crystal diamond / Ir / YSZ / Si(100) substrate to acid etching and mechanical polishing in sequence to remove YSZ / Si(100) and Ir in sequence to obtain single crystal diamond;

[0046] The acid etching method is as follows: a single crystal diamond / Ir / YSZ / Si(100) substrate is completely immersed in a mixed acid solution for etching, wherein the mixed acid solution is obtained by mixing 50wt.% of hydrofluoric acid and 60wt.% of nitric acid, wherein the volume ratio of hydrofluoric acid to nitric acid is 1:3, the etching temperature is 25°C, the etching time is 60min, and after the acid etching is completed, the etched substrate is fully cleaned with deionized water until the cleaning solution is neutral, thereby obtaining a substrate from which YSZ / Si(100) is removed;

[0047] The mechanical polishing method is: use diamond suspension to mechanically polish the YSZ / Si(100) substrate to remove Ir, the average particle size of diamond particles in the diamond suspension is 5nm, the polishing pressure is 2psi, the polishing time is 30min, and the surface roughness RMS of the single crystal diamond after polishing is 2nm. Then the single crystal diamond is cleaned 3 times with deionized water and blown dry with nitrogen to obtain single crystal diamond.

[0048] The preparation method of the Ir / YSZ / Si(100) substrate of this embodiment is as follows: a Si(100) wafer with a thickness of 2.0 mm is used as a substrate, and the wafer is placed in a vacuum chamber with a vacuum degree of In a high vacuum chamber of Torr, a pulsed laser deposition method was used to prepare YSZ with a thickness of 20 nm on a Si(100) wafer. The deposition temperature was 700°C, the wavelength of the pulsed laser was 248 nm, the laser repetition frequency was 5 Hz, the laser energy density was 1.5 J / cm², and 99.99% pure oxygen with a flow rate of 50 sccm was used as the reaction atmosphere. The deposition time was 15 min. After the deposition was completed and cooled to room temperature, YSZ / Si(100) was obtained. Then, the YSZ / Si(100) was transferred to an electron beam evaporation system and heated to room temperature. Under the conditions of 3000 Torr, use iridium with a purity of 99.99% as the evaporation source, control the evaporation rate to 0.05nm / s, the substrate rotation speed to 10rpm, the substrate temperature to 620℃, the deposited Ir layer thickness to 120nm, and slowly cool to room temperature after deposition.

[0049] The method for preparing the diamond / gallium oxide heterojunction of this embodiment is as follows: placing a single crystal diamond in a magnetron sputtering deposition chamber, The target and Zr target were sputtered in RF sputtering mode and DC sputtering mode respectively, with oxygen partial pressure of 0.010 mbar, substrate temperature of 550 °C, RF sputtering power of 100 W, DC sputtering power of 10 W, deposition time of 180 min, and deposition thickness of 300 nm. The Zr atomic doping amount is 0.50at.%. The carrier concentration is .

[0050] In the wavelength range of 210-280nm, the ratio of the response value at 210nm to the response value at 280nm is 150; the ratio of the response value at 240nm to the response value at 280nm is 90. The dark current of the diamond / gallium oxide heterojunction at a bias voltage of 10V is , the photocurrent under ultraviolet irradiation is .

[0051] pass Figure 1 It can be proved that the diamond / gallium oxide heterojunction prepared in Example 1 of the present invention has a clear layered structure, and the Zr doped It presents a columnar crystal morphology, indicating that the material has a high crystalline quality. Figure 2 The roughness of the polished single-crystal diamond surface was demonstrated, and the results showed that its roughness was only 2nm, proving that the surface was very smooth and conducive to the subsequent heterojunction growth. Figure 3 The XRD patterns further prove that Zr doping The diamond substrate is a single crystal diamond with (100) orientation and orderly growth on the surface of the single crystal diamond. This orderly oriented growth helps to improve the interface quality of the heterojunction. Finally, Figure 4 The transmission electron microscope (TEM) photo clearly shows the coherent interface of the heterojunction, proving that the lattice matching at the interface is good, which is of great significance for improving the optoelectronic performance of the heterojunction. The above analysis proves that the diamond / gallium oxide heterojunction prepared by the present invention has excellent quality in structure and interface, and can provide a good foundation for high-performance solar-blind ultraviolet detectors.

[0052] Embodiment 2:

[0053] A diamond / gallium oxide heterojunction comprises a single crystal diamond layer and a Zr-doped ε-Ga2O3 layer located on the single crystal diamond layer; the single crystal diamond layer is a single crystal diamond with a (100) orientation; the Zr-doped ε-Ga2O3 layer is Zr-doped ε-Ga2O3 heteroepitaxially grown on the surface of the single crystal diamond by a pulsed laser deposition method; the Zr-doped ε-Ga2O3 grows along the (001) direction on the surface of the single crystal diamond; the Zr-doped ε-Ga2O3 has a columnar crystal structure; and the interface between the single crystal diamond layer and the Zr-doped ε-Ga2O3 layer is a coherent interface.

[0054] The preparation method of the single crystal diamond in this embodiment is:

[0055] S1, placing the Ir / YSZ / Si(100) substrate into a microwave plasma enhanced chemical vapor deposition reactor, and sequentially performing nucleation treatment and growth treatment to obtain a single crystal diamond / Ir / YSZ / Si(100) substrate;

[0056] The process parameters of the nucleation treatment are: bias voltage of -285V, microwave power of 1060W, substrate temperature of 715℃, working pressure of 115mbar, mixed gas of methane, nitrogen and hydrogen as reaction atmosphere, methane volume fraction of the mixed gas is 3%, nitrogen content is 50ppm, flow rate of the mixed gas is 115sccm, and nucleation treatment time is 25min;

[0057] After the nucleation treatment is completed, the growth treatment is carried out, the growth treatment temperature remains unchanged, and the process parameters of the growth treatment are: the bias voltage is -235V, the microwave power is 930W, the working pressure is 165mbar, the mixed gas of methane, nitrogen and hydrogen is used as the reaction atmosphere, the volume fraction of methane in the mixed gas is 8%, the content of nitrogen is 100ppm, the flow rate of the mixed gas is 165sccm, and the growth treatment time is 216min. After the treatment, a single crystal diamond / Ir / YSZ / Si(100) substrate is obtained;

[0058] S2, then subjecting the single crystal diamond / Ir / YSZ / Si(100) substrate to acid etching and mechanical polishing in sequence to remove YSZ / Si(100) and Ir in sequence to obtain single crystal diamond;

[0059] The acid etching method is as follows: the single crystal diamond / Ir / YSZ / Si(100) substrate is completely immersed in a mixed acid solution for etching, wherein the mixed acid solution is obtained by mixing 50wt.% of hydrofluoric acid and 60wt.% of nitric acid, wherein the volume ratio of hydrofluoric acid to nitric acid is 1:3, the etching temperature is 28°C, and the etching time is 78min. After the acid etching is completed, the etched substrate is fully cleaned with deionized water until the cleaning solution is neutral, thereby obtaining a substrate with YSZ / Si(100) removed.

[0060] The mechanical polishing method is: use diamond suspension to mechanically polish the YSZ / Si(100) substrate to remove Ir, the average particle size of diamond particles in the diamond suspension is 7nm, the polishing pressure is 3psi, the polishing time is 42min, and the surface roughness RMS of the single crystal diamond after polishing is 4nm. Then the single crystal diamond is cleaned 3 times with deionized water and blown dry with nitrogen to obtain single crystal diamond.

[0061] The preparation method of the Ir / YSZ / Si(100) substrate of this embodiment is as follows: a Si(100) wafer with a thickness of 2.6 mm is used as a substrate, and the wafer is placed in a vacuum chamber with a vacuum degree of In a high vacuum chamber of Torr, a pulsed laser deposition method was used to prepare YSZ with a thickness of 29 nm on a Si(100) wafer. The deposition temperature was 715°C, the wavelength of the pulsed laser was 248 nm, the laser repetition frequency was 6 Hz, the laser energy density was 1.7 J / cm², and the flow rate was 65 sccm of 99.99% pure oxygen as the reaction atmosphere. The deposition time was 21 min. After the deposition was completed and cooled to room temperature, YSZ / Si(100) was obtained. Then, YSZ / Si(100) was transferred to an electron beam evaporation system and heated to room temperature. Under the conditions of 3000 Å / min, use iridium with a purity of 99.99% as the evaporation source, control the evaporation rate to 0.07 nm / s, the substrate rotation speed to 13 rpm, the substrate temperature to 631 °C, the deposited Ir layer thickness to 132 nm, and slowly cool to room temperature after deposition.

[0062] The method for preparing the diamond / gallium oxide heterojunction of this embodiment is as follows: placing a single crystal diamond in a magnetron sputtering deposition chamber, The target and Zr target were sputtered in RF sputtering mode and DC sputtering mode respectively, with oxygen partial pressure of 0.013 mbar, substrate temperature of 556 °C, RF sputtering power of 130 W, DC sputtering power of 22 W, deposition time of 198 min, and deposition thickness of 360 nm. The Zr atomic doping amount is 0.80at.%; Zr doping The carrier concentration is .

[0063] In the wavelength range of 210-280nm, the ratio of the response value at 210nm to the response value at 280nm is 159; the ratio of the response value at 240nm to the response value at 280nm is 97. The dark current of the diamond / gallium oxide heterojunction at a bias voltage of 10V is , the photocurrent under ultraviolet irradiation is .

[0064] Embodiment 3:

[0065] A diamond / gallium oxide heterojunction comprises a single crystal diamond layer and a Zr-doped ε-Ga2O3 layer located on the single crystal diamond layer; the single crystal diamond layer is a single crystal diamond with a (100) orientation; the Zr-doped ε-Ga2O3 layer is Zr-doped ε-Ga2O3 heteroepitaxially grown on the surface of the single crystal diamond by a pulsed laser deposition method; the Zr-doped ε-Ga2O3 grows along the (001) direction on the surface of the single crystal diamond; the Zr-doped ε-Ga2O3 has a columnar crystal structure; and the interface between the single crystal diamond layer and the Zr-doped ε-Ga2O3 layer is a coherent interface.

[0066] The preparation method of the single crystal diamond in this embodiment is:

[0067] S1, placing the Ir / YSZ / Si(100) substrate into a microwave plasma enhanced chemical vapor deposition reactor, and sequentially performing nucleation treatment and growth treatment to obtain a single crystal diamond / Ir / YSZ / Si(100) substrate;

[0068] The process parameters of the nucleation treatment are: bias voltage of -270 V, microwave power of 1120 W, substrate temperature of 730 ° C, working pressure of 130 mbar, methane, nitrogen and hydrogen mixed gas as the reaction atmosphere, the volume fraction of methane in the mixed gas is 3%, the content of nitrogen is 50 ppm, the flow rate of the mixed gas is 130 sccm, and the nucleation treatment time is 29 min;

[0069] After the nucleation treatment is completed, the growth treatment is carried out. The growth treatment temperature remains unchanged. The process parameters of the growth treatment are: bias voltage is -230V, microwave power is 960W, working pressure is 180mbar, and a mixed gas of methane, nitrogen and hydrogen is used as the reaction atmosphere. The volume fraction of methane in the mixed gas is 8%, the content of nitrogen is 100ppm, the flow rate of the mixed gas is 180sccm, and the growth treatment time is 264min. After the treatment, a single crystal diamond / Ir / YSZ / Si(100) substrate is obtained.

[0070] S2, then subjecting the single crystal diamond / Ir / YSZ / Si(100) substrate to acid etching and mechanical polishing in sequence to remove YSZ / Si(100) and Ir in sequence to obtain single crystal diamond;

[0071] The acid etching method is as follows: a single crystal diamond / Ir / YSZ / Si(100) substrate is completely immersed in a mixed acid solution for etching, wherein the mixed acid solution is obtained by mixing 50wt.% of hydrofluoric acid and 60wt.% of nitric acid, wherein the volume ratio of hydrofluoric acid to nitric acid is 1:3, the etching temperature is 31°C, and the etching time is 96min. After the acid etching is completed, the etched substrate is fully cleaned with deionized water until the cleaning solution is neutral, thereby obtaining a substrate from which YSZ / Si(100) is removed;

[0072] The mechanical polishing method is: use diamond suspension to mechanically polish the YSZ / Si(100) substrate to remove Ir, the average particle size of diamond particles in the diamond suspension is 8nm, the polishing pressure is 4psi, the polishing time is 48min, and the surface roughness RMS of the single crystal diamond after polishing is 5nm. Then the single crystal diamond is cleaned 3 times with deionized water and blown dry with nitrogen to obtain single crystal diamond.

[0073] The preparation method of the Ir / YSZ / Si(100) substrate of this embodiment is as follows: a Si(100) wafer with a thickness of 3.2 mm is used as a substrate, and the wafer is placed in a vacuum chamber with a vacuum degree of In a high vacuum chamber of Torr, a pulsed laser deposition method was used to prepare YSZ with a thickness of 38 nm on a Si(100) wafer. The deposition temperature was 730°C, the wavelength of the pulsed laser was 248 nm, the laser repetition frequency was 8 Hz, the laser energy density was 1.8 J / cm², and 99.99% pure oxygen with a flow rate of 80 sccm was used as the reaction atmosphere. The deposition time was 24 min. After the deposition was completed and cooled to room temperature, YSZ / Si(100) was obtained. Then, YSZ / Si(100) was transferred to an electron beam evaporation system and heated to room temperature at a vacuum of Under the conditions of 3000 Å / min, use iridium with a purity of 99.99% as the evaporation source, control the evaporation rate to 0.08 nm / s, the substrate rotation speed to 16 rpm, the substrate temperature to 640 °C, the thickness of the deposited Ir layer to be 144 nm, and slowly cool to room temperature after the deposition is completed.

[0074] The method for preparing the diamond / gallium oxide heterojunction of this embodiment is as follows: placing a single crystal diamond in a magnetron sputtering deposition chamber, The target and Zr target were sputtered in RF sputtering mode and DC sputtering mode respectively, with oxygen partial pressure of 0.016 mbar, substrate temperature of 562 °C, RF sputtering power of 160 W, DC sputtering power of 34 W, deposition time of 216 min, and deposition thickness of 420 nm. The Zr atomic doping amount is 1.10at.%. The carrier concentration is .

[0075] In the wavelength range of 210-280nm, the ratio of the response value at 210nm to the response value at 280nm is 168; the ratio of the response value at 240nm to the response value at 280nm is 104. The dark current of the diamond / gallium oxide heterojunction at a bias voltage of 10V is , the photocurrent under ultraviolet irradiation is .

[0076] Embodiment 4:

[0077] A diamond / gallium oxide heterojunction comprises a single crystal diamond layer and a Zr-doped ε-Ga2O3 layer on the single crystal diamond layer; the single crystal diamond layer is a (100) oriented single crystal diamond; the Zr-doped ε-Ga2O3 layer is a Zr-doped ε-Ga2O3 heteroepitaxially grown on the surface of the single crystal diamond by a pulsed laser deposition method; It grows along the (001) direction on the surface of single crystal diamond; the Zr-doped ε-Ga2O3 has a columnar crystal structure; and the interface between the single crystal diamond layer and the Zr-doped ε-Ga2O3 layer is a coherent interface.

[0078] The preparation method of the single crystal diamond in this embodiment is:

[0079] S1, placing the Ir / YSZ / Si(100) substrate into a microwave plasma enhanced chemical vapor deposition reactor, and sequentially performing nucleation treatment and growth treatment to obtain a single crystal diamond / Ir / YSZ / Si(100) substrate;

[0080] The process parameters of the nucleation treatment are: bias voltage of -250 V, microwave power of 1200 W, substrate temperature of 750 ° C, working pressure of 150 mbar, a mixed gas of methane, nitrogen and hydrogen as the reaction atmosphere, the volume fraction of methane in the mixed gas is 3%, the content of nitrogen is 50 ppm, the flow rate of the mixed gas is 150 sccm, and the nucleation treatment time is 35 min;

[0081] After the nucleation treatment is completed, the growth treatment is carried out. The growth treatment temperature remains unchanged. The process parameters of the growth treatment are: bias voltage is -200 V, microwave power is 1000 W, working pressure is 200 mbar, and a mixed gas of methane, nitrogen and hydrogen is used as the reaction atmosphere. The volume fraction of methane in the mixed gas is 8%, the content of nitrogen is 100 ppm, the flow rate of the mixed gas is 200 sccm, and the growth treatment time is 360 min. After the treatment, a single crystal diamond / Ir / YSZ / Si(100) substrate is obtained.

[0082] S2, then subjecting the single crystal diamond / Ir / YSZ / Si(100) substrate to acid etching and mechanical polishing in sequence to remove YSZ / Si(100) and Ir in sequence to obtain single crystal diamond;

[0083] The acid etching method is as follows: a single crystal diamond / Ir / YSZ / Si(100) substrate is completely immersed in a mixed acid solution for etching, wherein the mixed acid solution is obtained by mixing 50wt.% of hydrofluoric acid and 60wt.% of nitric acid, wherein the volume ratio of hydrofluoric acid to nitric acid is 1:3, the etching temperature is 35°C, and the etching time is 120min. After the acid etching is completed, the etched substrate is fully cleaned with deionized water until the cleaning solution is neutral, thereby obtaining a substrate with YSZ / Si(100) removed.

[0084] The mechanical polishing method is: use diamond suspension to mechanically polish the YSZ / Si(100) substrate to remove Ir, the average particle size of the diamond particles in the diamond suspension is 10nm, the polishing pressure is 5psi, the polishing time is 60min, and the surface roughness RMS of the single crystal diamond after polishing is 6nm. Then the single crystal diamond is cleaned 3 times with deionized water and blown dry with nitrogen to obtain single crystal diamond.

[0085] The preparation method of the Ir / YSZ / Si(100) substrate of this embodiment is as follows: a Si(100) wafer with a thickness of 4.0 mm is used as a substrate, and the wafer is placed in a vacuum chamber with a vacuum degree of In a high vacuum chamber of Torr, a pulsed laser deposition method was used to prepare YSZ with a thickness of 50 nm on a Si(100) wafer. The deposition temperature was 750°C, the wavelength of the pulsed laser was 248 nm, the laser repetition frequency was 10 Hz, the laser energy density was 2.0 J / cm², and 99.99% pure oxygen with a flow rate of 100 sccm was used as the reaction atmosphere. The deposition time was 30 min. After the deposition was completed and cooled to room temperature, YSZ / Si(100) was obtained. Then, YSZ / Si(100) was transferred to an electron beam evaporation system and heated to room temperature. Under the conditions of 3000 Å / min, use iridium with a purity of 99.99% as the evaporation source, control the evaporation rate to 0.1 nm / s, the substrate rotation speed to 20 rpm, the substrate temperature to 650 °C, the deposited Ir layer thickness to 150 nm, and slowly cool to room temperature after deposition.

[0086] The method for preparing the diamond / gallium oxide heterojunction of this embodiment is as follows: placing a single crystal diamond in a magnetron sputtering deposition chamber, The target and Zr target were sputtered in RF sputtering mode and DC sputtering mode respectively, with oxygen partial pressure of 0.020 mbar, substrate temperature of 570 °C, RF sputtering power of 200 W, DC sputtering power of 50 W, deposition time of 240 min, and deposition thickness of 500 nm. The Zr atomic doping amount is 1.50at.%; Zr doping The carrier concentration is .

[0087] In the wavelength range of 210-280nm, the ratio of the response value at 210nm to the response value at 280nm is 180; the ratio of the response value at 240nm to the response value at 280nm is 110. The dark current of the diamond / gallium oxide heterojunction at a bias voltage of 10V is , the photocurrent under ultraviolet irradiation is .

[0088] Comparative Example 1:

[0089] It is basically the same as Example 1, except that the substrate used for growing Zr-doped ε-Ga2O3 is polycrystalline diamond instead of single crystal diamond, and the polycrystalline diamond manufacturer is Zhengzhou Ward Superhard Materials Co., Ltd.

[0090] Comparative Example 2:

[0091] It is basically the same as Example 1, except that no doping treatment is used in the preparation of ε-Ga2O3.

[0092] The preparation method of undoped ε-Ga2O3 is as follows: a single crystal diamond is placed in a magnetron sputtering deposition chamber. The target material adopts RF sputtering mode, the oxygen partial pressure is 0.010mbar, the substrate temperature is 550°C, the RF sputtering power is set to 100W, the deposition time is 180min, and the deposition thickness is 300nm.

[0093] Comparative Example 3:

[0094] The method is basically the same as Example 1, except that the surface roughness RMS of the polished single crystal diamond is 10 nm.

[0095] The mechanical polishing method is as follows: a diamond suspension is used to mechanically polish the YSZ / Si(100) substrate to remove Ir, the average particle size of the diamond particles in the diamond suspension is 20 nm, the polishing pressure is 2 psi, the polishing time is 30 min, and the surface roughness RMS of the single crystal diamond after polishing is 10 nm. The single crystal diamond is then cleaned 3 times with deionized water and dried with nitrogen to obtain a single crystal diamond.

[0096] Performance Test:

[0097] The test method for the 210nm~280nm response value ratio is to irradiate the device with a UV light source and determine the response value at different wavelengths in combination with the measurement of photocurrent. The specific method is to use a UV light source system consisting of a white light source (EQ99XLDLS, Energetiq, the Netherlands) and a spectrophotometer (iHR320, Horiba, Japan) to select different wavelengths of UV light for irradiation within the wavelength range of 210nm to 280nm. The semiconductor parameter analyzer (Keithley4200-SCS, Tektronix, the United States) is used to measure the response value at each wavelength. / Photocurrent of diamond heterojunction photodetector. For each wavelength, the corresponding photocurrent is recorded and the ratio of the response values ​​at 210nm and 280nm is calculated.

[0098] The performances of the heterojunctions of Examples 1 to 4 and Comparative Examples 1 to 3 are summarized in Table 1.

[0099] Table 1 Performance convergence of heterojunctions of Examples 1 to 4 and Comparative Examples 1 to 3

[0100]

[0101] The main difference between Comparative Example 1 and Example 1 is that Comparative Example 1 uses polycrystalline diamond as the substrate, while Example 1 uses single crystal diamond. It can be seen from the data in the table that the 210nm / 280nm response value ratio of Comparative Example 1 is 110, which is significantly lower than 150 of Example 1. This shows that the polycrystalline diamond substrate has a weak response ability to short-wavelength ultraviolet light. The reason may be that the polycrystalline substrate has more grain boundary defects, which makes it easy for photogenerated carriers to recombine during the transmission process, thereby reducing the light response efficiency. Similarly, the 240nm / 280nm response value ratio in Comparative Example 1 is also significantly lower than that in Example 1 (60 vs. 90), which further shows that the ultraviolet response ability of the polycrystalline diamond substrate in the longer wavelength band is also poor. In terms of dark current, the dark current of Comparative Example 1 is , much higher than that of Example 1 This is because the grain boundary defects in the polycrystalline diamond substrate create more leakage paths, resulting in increased dark current and affecting the noise performance of the detector. Higher dark current means higher noise levels in the detector under no-light conditions, which has a negative impact on the sensitivity of the detector. In terms of photocurrent, the photocurrent of Comparative Example 1 is , lower than that of Example 1 The decrease in photocurrent is also related to the high defect density of the polycrystalline diamond substrate. The presence of grain boundary defects reduces the effective transmission of photogenerated carriers, resulting in a decrease in photocurrent. Finally, the light-to-dark current ratio of Comparative Example 1 is , much lower than that of Example 1 The significant decrease in the light-to-dark current ratio indicates that the detector prepared on the polycrystalline substrate has a larger noise and weaker signal recognition ability. Therefore, although the polycrystalline diamond substrate may have an advantage in cost, its performance is significantly inferior to that of the single crystal substrate, especially in sensitivity and noise performance.

[0102] The main difference between Comparative Example 2 and Example 1 is that The film was not doped, while Zr was doped in Example 1. As can be seen from the table, the 210nm / 280nm response value ratio of Comparative Example 2 is 90, which is much lower than 150 of Example 1. This shows that the undoped The material's response ability under short-wavelength ultraviolet light is significantly weaker. Doping can improve the separation efficiency of photogenerated carriers by introducing more free carriers, while the undoped material has a significantly reduced light response ability due to its low carrier concentration. Similarly, the 240nm / 280nm response value ratio in Comparative Example 2 is 55, which is also significantly lower than 90 in Example 1, indicating that the undoped material also has poor response ability in the long-wave band. In terms of dark current, the dark current of Comparative Example 2 is , slightly higher than that of Example 1 Undoped materials may have more intrinsic defects, which will generate a small amount of leakage current, resulting in a slight increase in dark current, but the magnitude is not large. In terms of photocurrent, the photocurrent of Comparative Example 2 is , significantly lower than that of Example 1 The main reason for the decrease in the photocurrent of the undoped material is the low generation and separation efficiency of the photogenerated carriers. Doping can effectively increase the photogenerated carrier concentration and mobility of the material, thereby increasing the photocurrent. The light-to-dark current ratio of Comparative Example 2 is , although slightly higher than that of Comparative Example 1 , but still much lower than that of Example 1 Doping can significantly improve the photoelectric performance of the detector. Undoped materials perform poorly in the separation and collection efficiency of photogenerated carriers, resulting in a decrease in photocurrent and an increase in noise, which ultimately reduces the signal recognition ability of the detector.

[0103] The main difference between Comparative Example 3 and Example 1 is that the diamond substrate surface roughness RMS of Comparative Example 3 is higher (10nm), while the surface of Example 1 is relatively smooth. As can be seen from the table, the 210nm / 280nm response value ratio of Comparative Example 3 is 130, slightly lower than 150 of Example 1. The increase in surface roughness will lead to more surface state defects, which cause surface recombination of photogenerated carriers, thereby reducing the light response efficiency of the material. Similarly, the 240nm / 280nm response value ratio in Comparative Example 3 is 75, which is also lower than 90 of Example 1, indicating that surface roughness also has a negative impact on the long-wave ultraviolet response. In terms of dark current, the dark current of Comparative Example 3 is , slightly higher than that of Example 1 The higher surface roughness increases the number of surface state defects, which become the source of leakage current and lead to the increase of dark current. In terms of photocurrent, the photocurrent of comparative example 3 is , slightly lower than that of Example 1 The increase in surface roughness causes some photogenerated carriers to scatter or recombine on the surface before reaching the electrode, resulting in a slight decrease in photocurrent. The light-to-dark current ratio of Comparative Example 3 is , which is significantly lower than that of Example 1 Although the effect of surface roughness is not as significant as that of doping and substrate material, it still has a certain negative impact on the optoelectronic performance of the detector, especially in terms of noise performance and signal recognition ability.

[0104] In summary, from the above comparison, it can be seen that the substrate material, doping treatment and surface roughness have a significant impact on the performance of the detector. Comparative Example 1 using a polycrystalline diamond substrate has the worst performance in terms of photoelectric performance and noise performance, mainly because the grain boundary defects of the polycrystalline substrate increase the dark current and reduce the photocurrent. In comparative example 2, the performance is also poor. Although the dark current is low, the light response ability and photocurrent are obviously insufficient, resulting in a decrease in the light-to-dark current ratio. The increase in surface roughness has a relatively small impact on the performance in comparative example 3, but it still leads to a decrease in the photocurrent and light-to-dark current ratio. Among all comparative examples, Example 1 always shows the best performance, indicating that the single crystal diamond substrate, Zr-doped And low surface roughness is the key factor to obtain high-performance solar-blind UV detectors.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that all equivalent structural changes made under the concept of the present invention and using the contents of the present invention specification and drawings should be covered within the scope of protection of the claims of the present invention.

Claims

1. A diamond / gallium oxide heterojunction, characterized in that: The diamond / gallium oxide heterojunction includes a single crystal diamond layer and a Zr-doped ε-Ga2O3 layer located on the single crystal diamond layer; The single crystal diamond layer is a single crystal diamond with a (100) orientation, and the surface roughness RMS of the single crystal diamond is 2-6 nm; The Zr-doped ε-Ga2O3 layer is Zr-doped ε-Ga2O3 heteroepitaxially grown on the surface of a single crystal diamond by a pulsed laser deposition method; the Zr-doped ε-Ga2O3 grows along the (001) direction on the surface of the single crystal diamond; the Zr-doped ε-Ga2O3 has a columnar crystal structure; The preparation method of the diamond / gallium oxide heterojunction comprises the following steps: placing a single crystal diamond in a magnetron sputtering deposition chamber, using an RF sputtering mode and a DC sputtering mode for a Ga2O3 target and a Zr target respectively, with an oxygen partial pressure of 0.010-0.020 mbar, a substrate temperature of 550-570°C, an RF sputtering power of 100-200 W, a DC sputtering power of 10-50 W, a deposition time of 180-240 min, and a deposition thickness of 300-500 nm.

2. The diamond / gallium oxide heterojunction according to claim 1, characterized in that The interface between the single crystal diamond layer and the Zr-doped ε-Ga2O3 layer is a coherent interface.

3. The diamond / gallium oxide heterojunction according to claim 1, characterized in that: The Zr atom doping amount of the Zr-doped ε-Ga2O3 is ; The carrier concentration of the Zr-doped ε-Ga2O3 is .

4. The diamond / gallium oxide heterojunction according to claim 1, characterized in that: The diamond / gallium oxide heterojunction has a wavelength range of 210-280 nm, a ratio of a response value at a wavelength of 210 nm to a response value at a wavelength of 280 nm of 150-180, and a ratio of a response value at a wavelength of 240 nm to a response value at 280 nm of 90-110.

5. The diamond / gallium oxide heterojunction according to claim 1, characterized in that: The dark current of the diamond / gallium oxide heterojunction at a bias voltage of 10 V is , the photocurrent under ultraviolet irradiation is .

6. The diamond / gallium oxide heterojunction according to claim 1, characterized in that: The method for preparing single crystal diamond comprises the following steps: The Ir / YSZ / Si(100) substrate is placed in a microwave plasma enhanced chemical vapor deposition reactor, and nucleation treatment and growth treatment are performed in sequence to obtain a single crystal diamond / Ir / YSZ / Si(100) substrate; then the single crystal diamond / Ir / YSZ / Si(100) substrate is subjected to acid etching and mechanical polishing in sequence to remove YSZ / Si(100) and Ir in sequence to obtain a single crystal diamond; The process parameters of the nucleation treatment are: bias voltage of -300~-250V, microwave power of 1000~1200W, substrate temperature of 700~750°C, working pressure of 100~150mbar, a mixed gas of methane, nitrogen and hydrogen as the reaction atmosphere, the volume fraction of methane in the mixed gas is 3~4%, the content of nitrogen is 40~60ppm, the flow rate of the mixed gas is 100~150sccm, and the nucleation treatment time is 20~35min; After the nucleation treatment is completed, the growth treatment is carried out, the growth treatment temperature remains unchanged, and the process parameters of the growth treatment are: bias voltage is -250~-200V, microwave power is 900~1000W, working pressure is 150~200mbar, and a mixed gas of methane, nitrogen and hydrogen is used as the reaction atmosphere. The volume fraction of methane in the mixed gas is 6.0~10.0%, the content of nitrogen is 90~110ppm, the flow rate of the mixed gas is 150~200sccm, and the growth treatment time is 120~360min.

7. The diamond / gallium oxide heterojunction according to claim 6, characterized in that: The acid etching method comprises the following steps: completely immersing a single crystal diamond / Ir / YSZ / Si(100) substrate in a mixed acid solution for etching, wherein the mixed acid solution is obtained by mixing hydrofluoric acid with a mass fraction of 45-55wt.% and nitric acid with a mass fraction of 55-65wt.%, wherein the volume ratio of the hydrofluoric acid to the nitric acid is 1:3, the etching temperature is 25-35°C, and the etching time is 60-120min; then, the etched substrate is fully cleaned with deionized water until the cleaning solution is neutral, thereby obtaining a substrate with YSZ / Si(100) removed; The mechanical polishing method comprises the following steps: using a diamond suspension to mechanically polish a substrate from which YSZ / Si(100) is removed to remove Ir, the average particle size of diamond particles in the diamond suspension is 5-10 nm, the polishing pressure is 2-5 psi, the polishing time is 30-60 min, the surface roughness RMS of the single crystal diamond after polishing is 2-6 nm, then the single crystal diamond is cleaned with deionized water, and dried by nitrogen, and finally the single crystal diamond is obtained.

8. The diamond / gallium oxide heterojunction according to claim 6, characterized in that: The preparation method of the Ir / YSZ / Si(100) substrate comprises the following steps: A Si (100) wafer with a thickness of 2.0 to 4.0 mm was used as the substrate and placed in a vacuum chamber. In a high vacuum chamber of Torr, a pulsed laser deposition method is used to prepare YSZ with a thickness of 20-50 nm on a Si(100) wafer. The deposition temperature is 700-750°C, the wavelength of the pulsed laser is 248 nm, the laser repetition frequency is 5-10 Hz, the laser energy density is 1.5-2.0 J / cm², and 99.99% pure oxygen with a flow rate of 50-100 sccm is used as the reaction atmosphere. The deposition time is 15-30 min, and YSZ / Si(100) is obtained after the deposition is completed and cooled to room temperature. Then YSZ / Si(100) was transferred to an electron beam evaporation system and Under the conditions of 3000 ℃ and 8000 ℃, use iridium with a purity of 99.99% as the evaporation source, control the evaporation rate to 0.05~0.1nm / s, the substrate rotation speed to 10~20rpm, the substrate temperature to 620~650℃, the thickness of the deposited Ir layer to 120~150nm, and slowly cool to room temperature after deposition.

9. Use of the diamond / gallium oxide heterojunction as claimed in any one of claims 1 to 8 in a solar-blind ultraviolet photodetector.

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