Thermal resistance regulation and control gallium oxide solar-blind ultraviolet micro-nano resonance sensor and preparation and detection method thereof

Abstract

The invention discloses a thermal resistance regulation and control gallium oxide solar-blind ultraviolet micro-nano resonance sensor and a preparation and detection method, and belongs to the technical field of optical sensors, a predefined groove is transversely etched in a SiO2 oxide layer, a strip-shaped beta-Ga2O3 thin film is transversely fixed on the SiO2 oxide layer, the strip-shaped beta-Ga2O3 thin film is located above the predefined groove, and the strip-shaped beta-Ga2O3 thin film is located above the predefined groove. And gaps exist between the two longitudinal sides, right above the pre-defined groove, of the strip-shaped beta-Ga2O3 thin film and the SiO2 oxide layer, so that the strip-shaped beta-Ga2O3 thin film is suspended on the pre-defined groove. According to the invention, solar blind ultraviolet light detection can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical sensors, and in particular relates to a thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor using thermal resistance control and a preparation and detection method thereof. Background Art

[0002] Solar-Blind Ultraviolet (SBUV) sensing technology is a technology used to detect ultraviolet radiation in the range of 200-280nm. The solar ultraviolet rays in this band are absorbed by the ozone layer during the process of radiating to the earth and cannot reach the earth's surface. Therefore, this band is called the solar-blind ultraviolet band.

[0003] β-Ga2O3 is an ultra-wide bandgap semiconductor material with a monoclinic crystal structure. Since the bandgap width of β-Ga2O3 is 4.8eV, the corresponding absorption cutoff wavelength is around 260-280nm, which coincides with the solar-blind ultraviolet band, and is an ideal material for solar-blind ultraviolet sensors. At present, gallium oxide photoelectric devices have attracted much attention in the field of solar-blind ultraviolet sensing. Gallium oxide photoelectric devices have the advantages of high sensitivity, high stability and fast response. Most gallium oxide photoelectric ultraviolet sensors are based on the preparation of gallium oxide thin films or gallium oxide materials. The responsiveness and sensitivity of gallium oxide photoelectric ultraviolet sensors are improved by continuously improving the preparation technology of gallium oxide materials and optimizing the structure of the device. However, due to the complex preparation technology of gallium oxide materials and the high price of high-quality thin films and single crystals, the preparation cost of the device is relatively high. In addition, the integration and packaging process of gallium oxide photoelectric devices is relatively complicated and easily interfered by the external environment, so there are many challenges in large-scale production and application.

[0004] Micro-Electro-Mechanical Systems (MEMS) refers to a miniaturized device or combination of devices, a comprehensive integrated system that combines electronic functions with mechanical, optical or other functions. When the characteristic size of the MEMS is reduced to below 300nm, it enters the stage of Nano-Electro-Mechanical Systems (NEMS). MEMS and NEMS have the characteristics of small size, light weight, low cost, low power consumption, and mass production that traditional devices do not have.

[0005] As a core M / NEMS device, the frequency of the resonator is one of the core parameters of the resonator, which greatly affects the impedance characteristics and sensitivity of the resonator-solar-blind UV sensor device. Compared with traditional UV photodetectors, M / NEMS resonators have a higher response rate and faster response speed to external disturbances, so β-Ga2O3 NEMS resonators will naturally show better solar-blind UV sensing performance. Research on β-Ga2O3 NEMS UV photodetectors is somewhat scarce, and the corresponding performance parameters still need to be further optimized according to specific application scenarios. Summary of the invention

[0006] Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention provides a thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor capable of detecting solar-blind ultraviolet light.

[0007] Technical solution: To achieve the above purpose, the technical solution adopted by the present invention is: A thermal resistance controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor comprises a Si substrate, a SiO2 oxide layer, and a strip-shaped β-Ga2O3 film, wherein the SiO2 oxide layer is arranged on the Si substrate, and the SiO2 oxide layer is etched with a predefined groove in the lateral direction, and one end of the strip-shaped β-Ga2O3 film is fixed on one lateral end of the SiO2 oxide layer, and the other end of the strip-shaped β-Ga2O3 film is fixed on the other lateral end of the SiO2 oxide layer. The strip-shaped β-Ga2O3 film is located above the predefined groove, and there is a gap between the longitudinal sides of the strip-shaped β-Ga2O3 film located directly above the predefined groove and the SiO2 oxide layer, so that the strip-shaped β-Ga2O3 film is suspended above the predefined groove.

[0008] Preferably, the resonant frequency of the NEMS thermal resistance-regulated gallium oxide solar-blind ultraviolet micro-nano resonant sensor is: ; in, represents the resonant frequency, represents the mode number, represents the sensor length, represents the sensor width, Indicates the sensor thickness, represents the internal stress, represents Young's modulus, Represents mass density.

[0009] Preferably, the band-shaped β-Ga2O3 film is irradiated with solar-blind ultraviolet light, and the resonant frequency under the solar-blind ultraviolet light irradiation is: ; in, represents the resonant frequency under solar-blind ultraviolet light irradiation, represents the mode number, represents the sensor length, represents Young's modulus, Indicates the sensor thickness, represents the mass density, represents the internal stress, represents the change in resonant frequency, is the incident light power, is the contact resistance, represents the fundamental frequency of the sensor, is the absorption coefficient, represents the temperature coefficient of Young's modulus, represents the thermal expansion coefficient of the β-Ga2O3 film

[100] crystal phase, [] refers to the atomic arrangement along the x, y, and z axes inside the crystal, represents the thermal expansion coefficient of the

[001] crystal phase of β-Ga2O3 film, represents the thermal expansion coefficient of the Si substrate.

[0010] Preferably, the dimensions of the predefined groove are: 10-20 μm in length, 2-6 μm in width, and 280-300 nm in height.

[0011] Preferably, the dimensions of the suspended portion of the strip-shaped β-Ga2O3 film are: 10-20 μm in length, 2-4 μm in width, and 290-310 nm in height.

[0012] Another object of the present invention is to provide a method for preparing a thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor, and the preparation of the thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor comprises the following steps: Step 1: Select a Si substrate and clean the surface of the substrate to remove impurities.

[0013] Step 2, generating a SiO2 oxide layer on the surface of the Si substrate to obtain an intermediate product 1.

[0014] Step 3, etching a predefined groove on the SiO2 oxide layer of the intermediate product one to obtain the intermediate product two.

[0015] Step 4, prepare β-Ga2O3 nanobelts, and use PDMS dry transfer technology to transfer the β-Ga2O3 nanobelts to the SiO2 oxide layer of the intermediate product 2 obtained in step 3, thereby completing the preparation of the NEMS thermal resistance controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor.

[0016] Preferably, the method for etching a predefined groove on the SiO2 oxide layer in step 3 is as follows: determine the predefined groove shape. Apply photoresist evenly on the upper surface of the SiO2 oxide layer of the intermediate product one. Use a photolithography machine to irradiate ultraviolet light on the photoresist surface to form the desired groove profile. Immerse the photolithographic intermediate product one in a developer to remove the photoresist of the unphotolithographic portion. Use a dry etching process to etch the groove shape. After etching is completed, clean the surface of the intermediate product one to remove the residual photoresist, and obtain an intermediate product two with clear predefined grooves.

[0017] Preferably, the method for preparing β-Ga2O3 nanobelts in step 4 is: synthesizing β-Ga2O3 single crystals by a reverse molding method, and then obtaining β-Ga2O3 nanobelts by a mechanical exfoliation method.

[0018] Preferably, in step 4, the method of transferring the β-Ga2O3 nanobelt onto the SiO2 oxide layer using the PDMS dry transfer technology is as follows: a Si substrate is selected and cleaned to remove impurities, Ga particles are used as raw materials in the reaction chamber, O2 is used as a gaseous precursor, and the β-Ga2O3 is grown at a temperature of 950°C for 1.5 hours, and the β-Ga2O3 is transformed from β-Ga2O3 nanocrystals to β-Ga2O3 nanorods and finally to β-Ga2O3 nanobelts.

[0019] Another object of the present invention is to provide a method for detecting solar-blinding ultraviolet rays, which uses the above-mentioned thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor, and uses a laser interferometer measurement system to emit laser to irradiate the strip-shaped β-Ga2O3 film. The suspended part of the strip-shaped β-Ga2O3 film will cause light interference, and the temperature will rise when irradiated by the laser, causing the vibration frequency to shift, resulting in a change in the intensity of the reflected light. The reflected light is detected by a photoelectric detector, and the voltage signal generated by the mechanical displacement of the sensor is measured. The signal emitted by the photoelectric detector is then recorded and processed by a spectrum analyzer, and the measured data is processed and analyzed, and finally the frequency response curve of the thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor is obtained, thereby realizing the detection of solar-blinding ultraviolet rays.

[0020] Another object of the present invention is to provide a laser interferometry measurement system, comprising the above-mentioned thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor based on thermal resistance control, a spectrum analyzer, a photoelectric detector, a spectroscope, a dichroic mirror, an objective lens, a red laser emitter, a blue laser emitter, and a vacuum chamber, wherein the thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor is arranged in the vacuum chamber, and the photoelectric detector, the spectroscope, the dichroic mirror, the objective lens, and the thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor are arranged along the detection light path, the red laser emitter is used to generate a red laser to irradiate the spectroscope, and the blue laser emitter is used to generate a blue laser to irradiate the dichroic mirror. The red laser is irradiated on the strip β-Ga2O3 film of the thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor through the dichroic mirror and the objective lens, and the blue laser is irradiated on the strip β-Ga2O3 film of the thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor through the objective lens.

[0021] Compared with the prior art, the present invention has the following beneficial effects: The thermal resistance regulated gallium oxide solar-blind ultraviolet micro-nano resonant sensor of the present invention is characterized by etching a predefined groove in the lateral direction on the SiO2 oxide layer, and the strip-shaped β-Ga2O3 film is laterally fixed on the SiO2 oxide layer, and the strip-shaped β-Ga2O3 film is located above the predefined groove, and there is a gap between the strip-shaped β-Ga2O3 film and the SiO2 oxide layer on both sides of the longitudinal direction directly above the predefined groove, so that the strip-shaped β-Ga2O3 film is suspended on the predefined groove. When the solar-blind ultraviolet light is irradiated on the thermal resistance regulated gallium oxide solar-blind ultraviolet micro-nano resonant sensor based on thermal resistance regulation, the photon energy is transferred to the lattice to generate heat, so that the temperature of the suspended β-Ga2O3 structure increases, causing the vibration frequency to shift, thereby realizing solar-blind ultraviolet light detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor; Figure 2 yes Figure 1 Middle AA section view; Figure 3 yes Figure 1 Middle BB section view; Figure 4 It is a schematic diagram of the laser interferometry process; Figure 5 This is a schematic diagram of the preparation process of the thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor; Figure 6 This is a schematic diagram of the signal transduction process of the thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor; Figure 7 This is a schematic diagram of the relationship between the absorptivity of β-Ga2O3 film and its thickness; Figure 8 This is a schematic diagram of the relationship between the resonant frequency of the thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor and the size and internal stress of the structure. Figure 8 The middle figure (a) is a schematic diagram of the relationship between thickness and frequency. Figure 8 The middle figure (b) is a schematic diagram of the relationship between length and frequency. Figure 8 The middle figure (c) is a schematic diagram of the relationship between internal stress and frequency; Fig. 9 It is a schematic diagram of the relationship between contact thermal resistance and responsiveness; Fig.10 This is a schematic diagram of the temperature distribution of the thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor; Fig.11 It is a schematic diagram of the temperature variation curve on the upper surface of β-Ga2O3; Fig.12 This is a schematic diagram of the frequency change and response of the thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor with temperature.

[0023] Among them, 1 is a Si substrate, 2 is a SiO2 oxide layer, 3 is a strip-shaped β-Ga2O3 film, and 4 is a predefined groove. DETAILED DESCRIPTION

[0024] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0025] Example 1 This embodiment provides a thermal resistance regulated gallium oxide solar-blind ultraviolet micro-nano resonant sensor, which is a micro-nano electromechanical resonant solar-blind ultraviolet resonator of β-Ga2O3 with mechanical resonant frequency shift regulated by thermal resistance, such as Figure 1-3As shown, it includes a Si substrate 1, a SiO2 oxide layer 2, and a strip-shaped β-Ga2O3 film 3. The SiO2 oxide layer 2 is arranged on the Si substrate 1. The SiO2 oxide layer 2 is etched with a predefined groove 4 in the lateral direction. In another embodiment, the size of the predefined groove 4 is: 10-20 μm long, 2-6 μm wide, and 280-300 nm high. In another embodiment, the size of the suspended part of the strip-shaped β-Ga2O3 film 3 is: 10-20 μm long, 2-4 μm wide, and 290-310 nm high. One end of the strip-shaped β-Ga2O3 film 3 is fixed on one lateral end of the SiO2 oxide layer 2, and the other end of the strip-shaped β-Ga2O3 film 3 is fixed on the other lateral end of the SiO2 oxide layer 2. The strip-shaped β-Ga2O3 film 3 is located above the predefined groove 4, and there is a gap between the strip-shaped β-Ga2O3 film 3 and the SiO2 oxide layer 2 on both sides of the longitudinal direction directly above the predefined groove 4, so that the strip-shaped β-Ga2O3 film 3 is suspended on the predefined groove 4.

[0026] In the NEMS thermal resistance regulated gallium oxide solar-blind ultraviolet micro-nano resonant sensor of this embodiment, its resonant frequency is a crucial parameter, which directly affects the performance and application of the device. The change of the resonant frequency can directly reflect the changes in the physical properties, geometric structure and external environment of the material. By studying and analyzing the resonant frequency, the sensitivity, responsiveness and other performance indicators of the thermal resistance regulated gallium oxide solar-blind ultraviolet micro-nano resonant sensor can be revealed. In order to optimize the design structure to achieve the desired resonant frequency, the resonant frequency calculation formula of the NEMS thermal resistance regulated gallium oxide solar-blind ultraviolet micro-nano resonant sensor is: (1) in, represents the resonant frequency, represents the mode number, represents the sensor length, Indicates the sensor thickness, represents the internal stress, represents Young's modulus, which is 261 GPa. Indicates mass density, take 5950kg / m 3 .

[0027] According to formula (1), the resonant frequency can be precisely controlled by adjusting the size (length, width, thickness) and internal stress of the sensor.

[0028] The thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor designed in this embodiment is a thermal detection device. When exposed to ultraviolet radiation, its temperature rises, causing a vibration frequency shift, thereby achieving ultraviolet detection.

[0029] The photothermal effect is mainly used to realize the solar-blind ultraviolet sensing of β-Ga2O3 NEMS sensor based on mechanical resonant frequency shift. The signal transduction process of thermal resistance-regulated gallium oxide solar-blind ultraviolet micro-nano resonant sensor is as follows: Figure 6 As shown in the figure, under SBUV irradiation, β-Ga2O3 absorbs photons with energy higher than the band gap. The photon energy is transferred to the lattice to generate heat, which increases the temperature of the suspended β-Ga2O3 structure. The generated heat diffuses along the β-Ga2O3 and eventually dissipates to the substrate. Therefore, the thermal resistance of the fixed beams at both ends of β-Ga2O3 and the contact thermal resistance between β-Ga2O3 and the substrate determine the temperature distribution of the device. The temperature distribution of the thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor can be expressed as: (2) in, It means that the temperature of the GaO2 solar-blind UV micro-nano resonant sensor is regulated by thermal resistance. represents the position on the β-Ga2O3 beam, is the temperature distribution on the β-Ga2O3 beam, is the temperature difference on the contact surface between β-Ga2O3 and Si substrate.

[0030] For the temperature distribution on the β-Ga2O3 beam, we can obtain: (3) in, represents the temperature distribution on the β-Ga2O3 beam, represents the heat flux, represents the thermal conductivity of β-Ga2O3, Indicates the sensor thickness, represents the sensor length, Indicates the position on the β-Ga2O3 beam.

[0031] for , we can assume a contact resistance , we can get: (4) (5) in, is the contact resistance, Optical absorption rate, is the incident light power, is the absorption coefficient, Indicates the sensor thickness.

[0032] According to formulas (2)-(5), the temperature distribution of the thermal resistance-controlled GaO solar-blind UV micro-nano resonant sensor is: (6) in, It means that the temperature of the GaO2 solar-blind UV micro-nano resonant sensor is regulated by thermal resistance. represents the heat flux, represents the thermal conductivity of β-Ga2O3, Indicates the sensor thickness, represents the sensor length, represents the position on the β-Ga2O3 beam, is the contact resistance, is the incident light power, is the absorption coefficient.

[0033] The temperature of the device rises under the irradiation of solar-blind ultraviolet light (SBUV), causing the mechanical resonance frequency of the device structure to change. Therefore, the overall responsivity of the β-Ga2O3 nanomechanical UV detector to UV radiation can be expressed as: (7) in, is the overall responsiveness, The mechanical resonance frequency changes. is the incident light power, is the optical absorption rate, is the contact resistance, is the linear temperature frequency coefficient, is the fundamental frequency of the sensor.

[0034] To analyze the temperature dependence of the β-Ga2O3 NEMS sensor, we used TC f There are two main reasons for the frequency drift caused by temperature changes: thermal expansion of the suspension structure and change in Young's modulus caused by temperature changes. The former can be expressed by the thermal expansion coefficient α to describe, while the latter can be described by the temperature coefficient of Young's modulus TCE Y To explain, the expression of the linear temperature-frequency coefficient of the NEMS thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor is: (8) in, is the linear temperature frequency coefficient, is the fundamental frequency of the sensor (the resonant frequency in the fundamental mode), that is, the initial resonant frequency, is the device temperature, represents the temperature coefficient of Young's modulus, represents the thermal expansion coefficient of the

[100] phase of the β-Ga2O3 film, [ ] refers to the atomic arrangement along the x, y, and z axes inside the crystal, represents the thermal expansion coefficient of the

[001] crystal phase of β-Ga2O3 film, represents the thermal expansion coefficient of the Si substrate.

[0035] The resonant frequency under solar-blind ultraviolet light is: (9) According to formulas (1), (7)-(9), the resonant frequency under solar-blind ultraviolet light irradiation is: (10) in, represents the resonant frequency under solar-blind ultraviolet light irradiation, represents the mode number, represents the sensor length, represents Young's modulus, Indicates the sensor thickness, represents the mass density, represents the internal stress, represents the change in resonant frequency, is the incident light power, is the contact resistance, represents the fundamental frequency of the sensor, is the absorption coefficient, represents the temperature coefficient of Young's modulus, represents the thermal expansion coefficient of the β-Ga2O3 film

[100] crystal phase, [] refers to the atomic arrangement along the x, y, and z axes inside the crystal, represents the thermal expansion coefficient of the

[001] crystal phase of β-Ga2O3 film, represents the thermal expansion coefficient of the Si substrate.

[0036] Example 2 This embodiment provides a method for preparing a thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor. The thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor in Example 1 is prepared. Figure 5 As shown, the following steps are included: Step 1: Select a Si substrate 1 and clean the surface of the substrate to remove impurities.

[0037] Step 2, forming a SiO2 oxide layer 2 on the surface of the Si substrate 1 to obtain an intermediate product 1.

[0038] Step 3, etching a predefined groove 4 on the SiO2 oxide layer 2 of the intermediate product 1 to obtain the intermediate product 2.

[0039] In another embodiment, a method for etching a predefined groove 4 on a SiO2 oxide layer 2 is as follows: determine the shape of the predefined groove, select a suitable intermediate product 1 (substrate) and determine the shape of the groove. Apply photoresist evenly on the upper surface of the SiO2 oxide layer 2 of the intermediate product 1. Use a photolithography machine to irradiate ultraviolet light on the surface of the photoresist to form the desired groove profile. Immerse the photolithographic intermediate product 1 in a developer to remove the photoresist of the unphotolithographic portion. Use a dry etching process to etch out the groove shape, prepare a rectangular micro-groove with a length of 10 to 20 μm, a width of 2 to 6 μm, and a depth of about 290 nm, and obtain the predefined groove 4. After etching is completed, clean the surface of the intermediate product 1 to remove the residual photoresist, and obtain an intermediate product 2 with a clear predefined groove 4.

[0040] Step 4, prepare β-Ga2O3 nanobelts (ribbon-shaped β-Ga2O3 films), and use PDMS dry transfer technology to transfer the β-Ga2O3 nanobelts onto the SiO2 oxide layer 2 of the intermediate product 2 obtained in step 3, thereby completing the preparation of the NEMS thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor.

[0041] In another embodiment, a method for preparing β-Ga2O3 nanobelts is as follows: β-Ga2O3 single crystals are synthesized by an inverted molding method, and then the β-Ga2O3 nanobelts are obtained by a mechanical exfoliation method.

[0042] In another embodiment, a method for transferring β-Ga2O3 nanobelts onto a SiO2 oxide layer 2 using PDMS dry transfer technology is as follows: a Si substrate is selected and cleaned to remove impurities, Ga particles are used as raw materials in a reaction chamber, O2 is used as a gaseous precursor, and the β-Ga2O3 is grown at a temperature of 950°C for 1.5 hours, from β-Ga2O3 nanocrystals to β-Ga2O3 nanorods, and finally to β-Ga2O3 nanobelts.

[0043] In another embodiment, a β-Ga2O3 nanobelt is synthesized, and then a suspended double-terminal fixed-supported ribbon-shaped β-Ga2O3 structure is prepared by using PDMS dry transfer technology: After determining the β-Ga2O3 nanobelts with the required size and thickness, we used dry transfer technology to transfer the thin film prepared on the PDMS stamp to the substrate with predefined grooves. The cured PDMS mold was aligned with the substrate on which the β-Ga2O3 nanobelts were grown. The PDMS was brought into close contact with the film by applying pressure. The PDMS mold was slowly separated from the substrate surface until the target sample was completely separated from the PDMS and transferred to the target substrate (with predefined rectangular grooves on the substrate). After the transfer was completed, the device was annealed as required to further ensure that there was no organic residue on the surface of the material. The transferred β-Ga2O3 ribbon was suspended on the 290nm deep micro-groove, forming a double-end clamped beam structure.

[0044] Using this method, we prepared a β-Ga2O3 NEMS sensor with a two-end clamped beam structure that was 10-20μm long, 2-4μm wide, and 300nm thick.

[0045] The present invention designs the sensor size based on the required sensor operating frequency range, and the fundamental frequency of the selected β-Ga2O3 NEMS sensor should meet the basic requirement of 10MHz-50MHz. By adjusting the length, width and thickness of the fixed beams at both ends, the fundamental frequency of the sensor can be accurately controlled; by adjusting the thermal resistance of the contact surface between β-Ga2O3 and the substrate, the size of the responsiveness can be further controlled to meet the performance requirements required for ultraviolet detection.

[0046] By theoretically analyzing formula (6), the relationship between the absorptivity of β-Ga2O3 film and its thickness is obtained, as follows: Figure 7 As shown. Then, by analyzing formula (1), the influence of the sensor's structural dimensions and internal stress on the resonant frequency is obtained, as shown in Figure 8 As shown. When designing the geometric dimensions of the resonant beam, we comprehensively considered the mechanical and thermal properties of the device to achieve precise control of the resonant frequency so that it meets the performance requirements for solar-blind ultraviolet detection. By analyzing the relationship between the frequency, size and internal stress of the sensor, we determined the dimensions of the resonant beam to be 12μm long, 4μm wide, 300nm thick, and 20MPa internal stress. Its fundamental mode resonant frequency is 14.5534MHz.

[0047] In the device design process, the regulation of contact surface thermal resistance has an important influence on the thermal performance of the device, which directly affects the heat transfer efficiency and the temperature distribution of the device. The contact surface pressure, roughness, thermal conductivity of the material, etc. have a direct impact on the size of the contact surface thermal resistance. Selecting a contact material with high thermal conductivity and low surface roughness can effectively reduce the contact surface thermal resistance, thereby improving the efficiency of heat conduction. At the same time, increasing the contact pressure helps to increase the effective area of ​​the contact surface, thereby reducing the contact surface thermal resistance. In theory, the smaller the contact surface thermal resistance, the higher the heat transfer efficiency, the less the temperature rise of the device, and the smaller the change in resonant frequency and the smaller the responsiveness. We use COMSOL to perform simulations to quantify the impact of contact surface thermal resistance. We use a smooth SiO2 oxide layer as the contact material with β-Ga2O3 to reduce the surface roughness and limit the total contact surface area to approximately 4×18μm 2 At the same time, we directly specify the contact surface thermal resistance to vary in the range of 0-20K / μW, and obtain that the change of the resonant frequency increases with the increase of the contact surface thermal resistance, and the responsiveness also increases with the increase of the contact surface thermal resistance, such as Fig. 9 shown.

[0048] Finally, we chose a device with a length of 12μm, a width of 4μm, a thickness of 300nm, an internal stress of 20MPa, and a contact surface thermal resistance of 5K / μW as an example. The fundamental mode resonant frequency of the sensor is 14.5534MHz. q =3W / cm 2 During operation, the color code diagram of the temperature distribution is as follows Fig.10 As shown in Figure 2, the heat flux is mainly concentrated in the suspended area of ​​β-Ga2O3 flakes (4×12μm 2 ), the temperature change mainly occurs on the β-Ga2O3 film ( Fig.11 ), showing a temperature change of only 0.06K, with the resonant frequency of the device shifting significantly as the temperature increases. Fig.12 The frequency curves of each mode of the sensor changing with temperature and the corresponding responsivity in the range of 300K to 313.25K are shown. The responsivity is approximately -10.25Hz / nW to -91.54Hz / nW.

[0049] Example 3 This embodiment provides a method for detecting solar-blind ultraviolet rays, which is detected by a laser interferometer measurement system. Figure 4As shown, the laser interferometry system includes the thermal resistance regulated gallium oxide solar-blind ultraviolet micro-nano resonant sensor described in Example 1, a spectrum analyzer, a photodetector for detecting device resonance, a spectroscope for setting an optical path, a dichroic mirror, an objective lens, a red laser emitter, a blue laser emitter for photothermal drive, and a vacuum chamber, wherein the vacuum chamber is provided with a vacuum gauge and an optical window, the NEMS thermal resistance regulated gallium oxide solar-blind ultraviolet micro-nano resonant sensor is arranged in the vacuum chamber, the photodetector, the spectroscope, the dichroic mirror, the objective lens, and the NEMS thermal resistance regulated gallium oxide solar-blind ultraviolet micro-nano resonant sensor are arranged along the detection optical path, the red laser emitter is used to generate a 633nm red laser to irradiate the spectroscope, the blue laser emitter is used to generate a 405nm blue laser to irradiate the dichroic mirror, and irradiate the NEMS thermal resistance regulated gallium oxide solar-blind ultraviolet micro-nano resonant sensor through the optical path for photothermal drive. The red laser is irradiated onto the strip-shaped β-Ga2O3 film 3 of the thermal resistance regulated gallium oxide solar-blind ultraviolet micro-nano resonant sensor through a dichroic mirror and an objective lens, and the blue laser is irradiated onto the strip-shaped β-Ga2O3 film 3 of the thermal resistance regulated gallium oxide solar-blind ultraviolet micro-nano resonant sensor through an objective lens. The suspended part of the strip-shaped β-Ga2O3 film 3 will cause light interference, and the temperature will rise when irradiated by the laser, causing the vibration frequency to shift, resulting in a change in the intensity of the reflected light. The reflected light is detected by a photoelectric detector, and the voltage signal generated by the mechanical displacement of the sensor is measured. The signal emitted by the photoelectric detector is then recorded and processed by a spectrum analyzer, and the measured data is processed and analyzed, and finally the frequency response curve of the thermal resistance regulated gallium oxide solar-blind ultraviolet micro-nano resonant sensor is obtained, thereby realizing the detection of solar-blind ultraviolet rays.

[0050] In this embodiment, when the laser is irradiated on the vibrating part of the NEMS sensor, light interference occurs, and the total reflectivity depends on the gap distance between β-Ga2O3 and the bottom surface of the groove, which will produce a corresponding phase difference. When the suspended β-Ga2O3 vibrates during resonance, while the bottom surface of the groove remains stable, the gap distance between β-Ga2O3 and the bottom surface of the groove changes, and this change causes the intensity of the reflected light to change. By using a photodetector to detect the reflected light, the voltage signal generated by the mechanical displacement of the sensor is measured, and then a spectrum analyzer is used to record and process the signal emitted by the photodetector, and the measured data is processed and analyzed, and finally the frequency response curve of the NEMS sensor is obtained, thereby realizing the detection of solar-blind ultraviolet rays.

[0051] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A thermal resistance controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor, characterized in that: The invention comprises a Si substrate (1), a SiO2 oxide layer (2), and a strip-shaped β-Ga2O3 film (3), wherein the SiO2 oxide layer (2) is arranged on the Si substrate (1), the SiO2 oxide layer (2) is etched with a predefined groove (4) in the lateral direction, one end of the strip-shaped β-Ga2O3 film (3) is fixed on one lateral end of the SiO2 oxide layer (2), and the other end of the strip-shaped β-Ga2O3 film (3) is fixed on the other lateral end of the SiO2 oxide layer (2); the strip-shaped β-Ga2O3 film (3) is located above the predefined groove (4), and there is a gap between the two longitudinal sides of the strip-shaped β-Ga2O3 film (3) located directly above the predefined groove (4) and the SiO2 oxide layer (2), so that the strip-shaped β-Ga2O3 film (3) is suspended above the predefined groove (4).

2. According to claim 1, the thermal resistance controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor is characterized in that: The resonant frequency of the thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor is: ； in, represents the resonant frequency, represents the mode number, represents the sensor length, represents the sensor width, Indicates the sensor thickness, represents the internal stress, represents Young's modulus, Represents mass density.

3. The thermal resistance controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor according to claim 2 is characterized in that: When the strip-shaped β-Ga2O3 film (3) is irradiated with solar-blind ultraviolet light, the resonant frequency under the solar-blind ultraviolet light is: in, represents the resonant frequency under solar-blind ultraviolet light irradiation, represents the mode number, represents the sensor length, represents Young's modulus, Indicates the sensor thickness, represents the mass density, represents the internal stress, represents the change in resonant frequency, is the incident light power, is the contact resistance, represents the fundamental frequency of the sensor, is the absorption coefficient, represents the temperature coefficient of Young's modulus, represents the thermal expansion coefficient of the [100] phase of the β-Ga2O3 film, [ ] refers to the atomic arrangement along the x, y, and z axes inside the crystal, represents the thermal expansion coefficient of the [001] crystal phase of β-Ga2O3 film, represents the thermal expansion coefficient of the Si substrate.

4. The thermal resistance controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor according to claim 3 is characterized in that: The dimensions of the predefined groove (4) are: 10-20 μm in length, 2-6 μm in width, and 280-300 nm in height; the dimensions of the suspended portion of the strip-shaped β-Ga2O3 film (3) are: 10-20 μm in length, 2-4 μm in width, and 290-310 nm in height.

5. A method for preparing the thermal resistance controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor as claimed in claim 1, characterized in that: The following steps are involved: Step 1, select a Si substrate (1), clean the surface of the substrate to remove impurities; Step 2, forming a SiO2 oxide layer (2) on the surface of the Si substrate (1) to obtain an intermediate product 1; Step 3, etching a predefined groove (4) on the SiO2 oxide layer (2) of the intermediate product 1 to obtain the intermediate product 2; Step 4, prepare β-Ga2O3 nanobelts, and use PDMS dry transfer technology to transfer the β-Ga2O3 nanobelts onto the SiO2 oxide layer (2) of the intermediate product 2 obtained in step 3, thereby completing the preparation of the thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor.

6. The preparation method according to claim 5, characterized in that: The method for etching a predefined groove (4) on the SiO2 oxide layer (2) in step 3 comprises: determining the shape of the predefined groove; uniformly applying a photoresist on the upper surface of the SiO2 oxide layer (2) of the intermediate product 1; Using a photolithography machine to irradiate ultraviolet light on the surface of the photoresist to form the desired groove profile; immersing the photolithographic intermediate product in a developer to remove the photoresist in the unlithographic portion; using a dry etching process to etch out the groove shape; After the etching is completed, the surface of the intermediate product 1 is cleaned to remove the residual photoresist, thereby obtaining an intermediate product 2 having a clear predefined groove (4).

7. The preparation method according to claim 6, characterized in that: The method for preparing β-Ga2O3 nanobelts in step 4 is: synthesizing β-Ga2O3 single crystals by the inverted molding method, and then obtaining β-Ga2O3 nanobelts by the mechanical exfoliation method.

8. The preparation method according to claim 7, characterized in that: In step 4, the PDMS dry transfer technology is used to transfer the β-Ga2O3 nanobelt onto the SiO2 oxide layer (2): a Si substrate is selected and cleaned to remove impurities, Ga particles are used as raw materials in the reaction chamber, O2 is used as a gaseous precursor, and the β-Ga2O3 is grown at a temperature of 950°C for 1.5 hours, and the β-Ga2O3 is transformed from β-Ga2O3 nanocrystals to β-Ga2O3 nanorods and finally to β-Ga2O3 nanobelts.

9. A method for detecting solar-blind ultraviolet rays of the thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor as claimed in claim 1, characterized in that: A laser is emitted through a laser interferometer measurement system to irradiate the strip-shaped β-Ga2O3 film (3). The suspended part of the strip-shaped β-Ga2O3 film (3) will cause light interference. When irradiated by the laser, the temperature rises, causing the vibration frequency to shift, resulting in a change in the intensity of the reflected light. The reflected light is detected by a photodetector, and the voltage signal generated by the mechanical displacement of the sensor is measured. The signal emitted by the photodetector is then recorded and processed by a spectrum analyzer. The measured data is processed and analyzed, and finally the frequency response curve of the thermal resistance-controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor is obtained, thereby realizing the detection of solar-blind ultraviolet rays.

10. A laser interferometry system, characterized in that: The invention comprises the thermal resistance controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor as claimed in claim 1, a spectrum analyzer, a photoelectric detector, a spectroscope, a dichroic mirror, an objective lens, a red laser emitter, a blue laser emitter, and a vacuum chamber, wherein the thermal resistance controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor is arranged in the vacuum chamber, the photoelectric detector, the spectroscope, the dichroic mirror, the objective lens, and the thermal resistance controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor are arranged along the detection light path, the red laser emitter is used to generate red laser to irradiate the spectroscope, the blue laser emitter is used to generate blue laser to irradiate the dichroic mirror, the red laser is irradiated on the strip-shaped β-Ga2O3 film (3) of the thermal resistance controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor through the dichroic mirror and the objective lens, and the blue laser is irradiated on the strip-shaped β-Ga2O3 film (3) of the thermal resistance controlled gallium oxide solar-blind ultraviolet micro-nano resonant sensor through the objective lens.

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