A gas sensor and preparation method thereof, and a method for measuring gas composition and gas pressure

Abstract

The present invention provides a gas sensor and a preparation method, and a method for measuring gas composition and air pressure. The gas sensor comprises: a SrTiO3 substrate, a LaFeO3 film, a LaAlO3 film, an adhesion layer and a back electrode; the SrTiO3 substrate comprises a polished surface and a rough surface; the polished surface is grown with the LaFeO3 film, and the LaAlO3 film is grown on the LaFeO3 film; the rough surface is plated with the adhesion layer and the back electrode, and the back electrode is connected to a temperature control platform. The gas sensor of the present invention has a simple structure and low cost, can work stably at extremely low temperatures (-273°C) to 150°C, and has high application value in extreme environments.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas sensors, and in particular relates to a gas sensor and a preparation method thereof, and a method for measuring gas composition and gas pressure. Background Art

[0002] Resistive gas sensors are widely used to detect gas composition, air pressure, etc. Their working principle is usually that the gas to be measured contacts the sensor surface, causing carrier changes, thereby changing the resistance or current of the sensor.

[0003] However, the current resistive gas sensors require a high operating temperature (≥100°C), a narrow operating temperature range, a long time to stabilize, and complex devices, which are not suitable for extreme environments such as aviation or extraterrestrial exploration. Therefore, it is urgent to develop a gas sensor that can work in low temperature to room temperature environments. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a gas sensor and a preparation method, and a method for measuring gas composition and air pressure. The gas sensor of the present invention has a simple structure and low cost, can work stably at extremely low temperatures (-273°C) to 150°C, and has high application value in extreme environments.

[0005] On the one hand, to achieve the above-mentioned object, the present invention provides a gas sensor, comprising: a SrTiO3 substrate, a LaFeO3 film, a LaAlO3 film, an adhesion layer and a back electrode;

[0006] The SrTiO3 substrate comprises a polished surface and a rough surface;

[0007] The LaFeO3 film is grown on the polished surface, and the LaAlO3 film is grown on the LaFeO3 film;

[0008] The rough surface is plated with the adhesion layer and the back electrode, and the back electrode is connected to the temperature control platform.

[0009] Optionally, the SrTiO3 substrate is a single-sided polished (001) oriented perovskite phase single crystal SrTiO3 substrate of a first preset thickness, and the thickness of the SrTiO3 substrate is ≤0.5 mm;

[0010] The LaFeO3 film is a (001) oriented single crystal LaFeO3 film of a perovskite phase with a second preset thickness, and the thickness of the LaFeO3 film is 2-10 monolayers;

[0011] The LaAlO3 film is a (001) oriented single crystal LaAlO3 film of a perovskite phase with a third preset thickness, and the thickness of the LaAlO3 film is 2-15 monolayers;

[0012] The adhesion layer and the back electrode are metal layers of different elements.

[0013] In order to achieve the above object, the present invention provides a method for preparing a gas sensor, comprising:

[0014] Pre-treating the SrTiO3 substrate;

[0015] Epitaxially growing an oxide film on the pretreated SrTiO3 substrate;

[0016] The SrTiO3 substrate on which the oxide film is grown is subjected to magnetron metal sputtering to obtain the gas sensor, and the gas sensor is adhered to a temperature control platform.

[0017] Optionally, pre-treating the SrTiO3 substrate comprises:

[0018] The SrTiO3 substrate is cleaned, and the cleaned SrTiO3 substrate is subjected to etching and annealing treatment.

[0019] Optionally, cleaning the SrTiO3 substrate includes:

[0020] The SrTiO3 substrate is placed in acetone for ultrasonic cleaning to remove organic impurities on the surface of the SrTiO3 substrate, and then ultrasonically cleaned in anhydrous ethanol to remove acetone and other impurities on the surface of the SrTiO3 substrate.

[0021] Optionally, performing etching annealing treatment on the cleaned SrTiO3 substrate comprises:

[0022] The cleaned SrTiO3 substrate was ultrasonically reacted in deionized water for 30 minutes, then etched in BOE buffer for 30 seconds, then washed in deionized water and the water adsorbed on the surface was blown dry with nitrogen, and the etched substrate was annealed at 950°C for 90 minutes.

[0023] Optionally, epitaxially growing an oxide film comprises:

[0024] The pretreated SrTiO3 substrate is placed in a pulsed laser deposition chamber, and the chamber is evacuated to a pressure of less than 10 -7 mbar; then fill the cavity with oxygen to make the pressure in the cavity reach 10 -5 -10 -4mbar; heating the SrTiO3 substrate to 650-750°C, epitaxially growing 2-10 monolayers of the LaFeO3 film on the SrTiO3 substrate, epitaxially growing 2-15 monolayers of the LaAlO3 film based on the LaFeO3 film, and monitoring the number of film growth layers by a reflection high energy electron diffractometer.

[0025] Optionally, performing magnetron metal sputtering includes:

[0026] The SrTiO3 substrate with the thin film grown is placed in a magnetron sputtering chamber, a first element metal with a thickness of ≥5nm is sputtered on the rough surface of the SrTiO3 substrate as an adhesion layer, and a second element metal with a thickness of ≥5nm is sputtered as a back electrode, wherein the first element metal is different from the second element metal.

[0027] On the other hand, to achieve the above-mentioned purpose, the present invention also provides a method for measuring gas composition and gas pressure, characterized in that, based on the above-mentioned gas sensor, after cooling to below the freezing point of the gas through a small temperature control platform, a back gate electric field is applied to adsorb solid gas molecules on the surface of the gas sensor;

[0028] The gas sensor is heated at a constant heating rate using a temperature control platform, the surface temperature and resistance of the gas sensor are recorded in real time, and a first-order differential curve of resistance and temperature is drawn. The temperature corresponding to the minimum value of the curve is the boiling point or sublimation temperature of the gas.

[0029] The gas pressure is derived from the boiling point or sublimation temperature and the three-phase diagram of the gas.

[0030] Optionally, the applied back gate electric field is ≥500 V / cm.

[0031] Compared with the prior art, the present invention has the following advantages and technical effects:

[0032] 1. The gas sensor proposed in the present invention has a simple structure, low cost, small oxide lattice mismatch, high feasibility, can be prepared on a large scale, is easy to industrialize, and has strong practical value;

[0033] 2. The gas sensor material has good stability and a large operating temperature window, and is suitable for extreme environments such as aviation and extraterrestrial exploration;

[0034] 3. The resistance change caused by gas desorption is obvious, and various gas components can be measured and the gas pressure can be estimated. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0036] Figure 1 This is a schematic diagram of the structure of a gas sensor according to Embodiment 1 of the present invention;

[0037] Figure 2 Schematic diagram of the R (resistance)-T (temperature) curve and dR / dT (first-order differential of resistance)-T curve of the gas sensor in Example 3 of the present invention during the temperature rise process after the back gate electric field is applied at 2K;

[0038] Figure 3 It is a schematic diagram of the RT curve of the gas sensor in Example 3 of the present invention during the heating process after the back gate electric field is applied to the gas sensor at different temperatures. DETAILED DESCRIPTION

[0039] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0040] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0041] Example 1

[0042] like Figure 1 As shown, this embodiment provides a gas sensor, including: a SrTiO3 substrate, a LaFeO3 film, a LaAlO3 film, an adhesion layer and a back electrode;

[0043] The SrTiO3 substrate comprises a polished surface and a rough surface;

[0044] The LaFeO3 film is grown on the polished surface, and the LaAlO3 film is grown on the LaFeO3 film;

[0045] The rough surface is plated with the adhesion layer and the back electrode, and the back electrode is connected to the temperature control platform.

[0046] Further, the SrTiO3 substrate is a perovskite phase single crystal SrTiO3 substrate with a first preset thickness and a single-side polishing and a preset orientation, and the thickness thereof is ≤0.5 mm;

[0047] The LaFeO3 film is a preset oriented single crystal LaFeO3 film of a perovskite phase with a second preset thickness, and the thickness thereof is 2-10 monolayers;

[0048] The LaAlO3 film is a preset oriented single crystal LaAlO3 film of a perovskite phase with a third preset thickness, and the thickness thereof is 2-15 monolayers;

[0049] The adhesion layer and the back electrode are metal layers of different elements.

[0050] The gas sensor in this embodiment includes a single-sided polished SrTiO3 substrate, a LaFeO3 film is grown on the polished surface of the SrTiO3 substrate, a LaAlO3 film is grown on the LaFeO3 film, and a metal is plated on the rough surface of the SrTiO3 substrate as an adhesion layer and a back electrode, and the back electrode is adhered to a small temperature-controlled platform.

[0051] The SrTiO3 substrate is a single-sided polished (001) oriented perovskite phase single crystal SrTiO3 substrate with a thickness of ≤0.5 mm.

[0052] The LaFeO3 film grown on the polished surface of the SrTiO3 substrate is a (001) oriented single crystal LaFeO3 film of the perovskite phase, with a thickness of 2-10 monolayers; the LaAlO3 film grown on the LaFeO3 film is a (001) oriented single crystal LaAlO3 film of the perovskite phase, with a thickness of 2-15 monolayers.

[0053] The rough surface of the SrTiO3 substrate is plated with metals such as Ni, Ti or Al as an adhesion layer, and the adhesion layer is plated with metals such as Pt or Au as a back electrode.

[0054] Example 2

[0055] This embodiment provides a method for preparing a gas sensor, comprising:

[0056] (1) SrTiO3 substrate cleaning;

[0057] (2) SrTiO3 substrate etching annealing;

[0058] (3) placing the SrTiO3 substrate into a pulsed laser deposition chamber and epitaxially growing 2-10 monolayers of LaFeO3 thin film on the polished surface;

[0059] (4) growing 2-15 monolayers of LaAlO3 film on LaFeO3 film;

[0060] (5) placing the SrTiO3 substrate into a magnetron sputtering chamber and sputtering metals such as Ni, Ti or Al on the rough surface as an adhesion layer;

[0061] (6) sputtering a metal such as Pt or Au on the adhesion layer as a back electrode to obtain a gas sensor component;

[0062] (7) Adhere the gas sensor components to a small temperature control platform to make them conduct heat well, thereby obtaining a gas sensor;

[0063] Furthermore, in step (3) and step (4): the SrTiO3 substrate is placed in a pulsed laser deposition chamber, the SrTiO3 substrate is heated, and after reaching a preset temperature, a pulsed laser with a wavelength of 248nm is used to sputter the target material, and LaFeO3 ceramic target (≥99.9%) and LaAlO3 target (≥99.9%) are used as target sources to epitaxially grow LaFeO3 and LaAlO3 films on the polished surface of the SrTiO3 substrate.

[0064] Furthermore, the energy density of the pulsed laser energy sputtered on the target source is 0.2-3J / cm 2 The pulse frequency is 1-10 Hz, the epitaxial growth temperature is 650-750 ° C, and oxygen is introduced into the pulse laser deposition chamber to supplement the oxygen vacancies in the film to stabilize the film phase. The oxygen pressure is 10 -5 -10 -4 mbar.

[0065] Furthermore, in step (5) and step (6): the SrTiO3 substrate is placed in a magnetron sputtering chamber, and the thickness of the metal such as Ni, Ti or Al as the adhesion layer and the metal such as Pt or Au as the back electrode are both ≥5nm.

[0066] Furthermore, the specific steps include:

[0067] (1) SrTiO3 substrate cleaning: The SrTiO3 substrate is ultrasonically cleaned in acetone for ≥5 min to remove organic impurities on the surface, and then ultrasonically cleaned in anhydrous ethanol for ≥5 min to remove acetone and other impurities on the surface;

[0068] (2) SrTiO3 substrate etching annealing: The cleaned SrTiO3 substrate was subjected to ultrasonic reaction in deionized water for 30 min, then etched in BOE (Buffered Oxide Etch) buffer for 30 s, then rinsed in deionized water and the water adsorbed on the surface was blown dry with nitrogen, and the etched substrate was annealed at 950°C for 90 min to obtain a Ti-O layer-cutoff SrTiO3 substrate with a high-quality step surface;

[0069] (3) Epitaxial growth of oxide thin films: The annealed SrTiO3 substrate is placed in a pulsed laser deposition chamber and the chamber is first evacuated to a pressure of <10 -7 mbar; then fill the cavity with oxygen to 10-5 -10 -4 mbar; the SrTiO3 substrate is heated to 650-750℃, 2-10 monolayers of LaFeO3 film are epitaxially grown on the substrate, and 2-15 monolayers of LaAlO3 film are epitaxially grown, and the number of film growth layers is monitored by reflection high energy electron diffractometer (RHEED); the pulsed laser wavelength sputtered on the LaFeO3 ceramic target and the LaAlO3 target is 248nm, and the energy density is 0.2-3J / cm 2 , frequency is 1-10Hz;

[0070] (4) The sample on which the thin film has been grown is placed in a magnetron sputtering chamber, and a metal such as Ni, Ti or Al with a thickness of ≥5 nm is sputtered on the rough surface of the SrTiO3 substrate as an adhesion layer, and then a metal such as Pt or Au with a thickness of ≥5 nm is sputtered as a back electrode to obtain a gas sensor component; the adhesion layer is a first element metal, and the back electrode is a second element metal, and the first element metal can enhance the adhesion between the substrate and the second element metal.

[0071] (5) The gas sensor components are adhered to a small temperature control platform. The temperature control platform is equipped with a PID controller that can achieve constant rate heating and cooling, and is equipped with a thermocouple that can monitor the surface temperature in real time and output the temperature data.

[0072] As an implementation method of this embodiment, a method for preparing a gas sensor of this embodiment has the following specific steps:

[0073] (1) SrTiO3 substrate cleaning: The SrTiO3 substrate was ultrasonically cleaned in acetone for 10 min to remove organic impurities on the surface, and then ultrasonically cleaned in anhydrous ethanol for 10 min to remove acetone and other impurities on the surface;

[0074] (2) SrTiO3 substrate etching annealing: The cleaned SrTiO3 substrate was ultrasonically reacted in deionized water for 30 minutes, then etched in BOE solution for 30 seconds, then rinsed in deionized water and the water adsorbed on the surface was blown dry with nitrogen, and the etched substrate was annealed at 950°C for 90 minutes to obtain a Ti-O layer-cut-off SrTiO3 substrate with a high-quality step surface;

[0075] (3) Epitaxial growth of oxide thin films: The annealed SrTiO3 substrate is placed in a pulsed laser deposition chamber and the chamber is evacuated to 10 -8 mbar; then fill the cavity with oxygen to 10 -5mbar; the SrTiO3 substrate was heated to 700°C, and two monolayers of LaFeO3 thin film were epitaxially grown on the substrate, and then 10 monolayers of LaAlO3 thin film were epitaxially grown, and the number of film growth layers was monitored by reflection high energy electron diffractometer (RHEED); the pulsed laser wavelength of the sputtered polycrystalline LaFeO3 ceramic target (99.99%) and single crystal LaAlO3 target (99.99%) in the perovskite phase was 248nm, and the energy density was 1J / cm 2 , frequency is 2Hz;

[0076] (4) placing the sample on which the thin film was grown into a magnetron sputtering chamber, sputtering a 20 nm thick Ti as an adhesion layer on the rough surface of the SrTiO3 substrate, and then sputtering a 20 nm thick Pt as a back electrode, to obtain a gas sensor component;

[0077] The resistance-temperature characteristics of the prepared gas sensor components were tested to study the sensitivity of their resistance to gas desorption:

[0078] Connect the source-surface four-probe to the four corners of the upper surface of the sample, cool it to -271.15°C, apply a back gate electric field of 4200V / cm to adsorb solid gas molecules for 2s and then remove them, and heat it at a constant rate of 5°C / min.

[0079] The resistance-time characteristics were measured using the Van der Pauw method. The positive electrode of the back gate electric field was connected to the Pt back electrode, and the negative electrode was connected to the upper surface of the sample. One data point was measured every 1°C, and R (resistance)-T (temperature) and dR / dT (first-order differential of resistance)-T curves were plotted, as shown in Figure 2. Figure 2 As shown, it can be seen that gas desorption will cause a significant change in the resistance of the gas sensor

[0080] Furthermore, after applying the back gate electric field at different temperatures, the temperature is increased, and one data point is measured every 1°C to draw the RT curve, such as Figure 3 As shown, it can be seen that when the temperature of applying the back gate electric field is higher than the freezing point of a certain gas, the resistance change of the gas sensor caused by gas desorption will disappear.

[0081] Another method for preparing a gas sensor in this embodiment includes the following specific steps:

[0082] (1) SrTiO3 substrate cleaning: The SrTiO3 substrate was ultrasonically cleaned in acetone for 10 min to remove organic impurities on the surface, and then ultrasonically cleaned in anhydrous ethanol for 10 min to remove acetone and other impurities on the surface;

[0083] (2) SrTiO3 substrate etching annealing: The cleaned SrTiO3 substrate was ultrasonically reacted in deionized water for 30 minutes, then etched in BOE solution for 30 seconds, then rinsed in deionized water and the water adsorbed on the surface was blown dry with nitrogen, and the etched substrate was annealed at 950°C for 90 minutes to obtain a Ti-O layer-cut-off SrTiO3 substrate with a high-quality step surface;

[0084] (3) Epitaxial growth of oxide thin films: The annealed SrTiO3 substrate is placed in a pulsed laser deposition chamber and the chamber is evacuated to 10 -8 mbar; then fill the cavity with oxygen to 5*10 -5 mbar; the SrTiO3 substrate was heated to 700°C, and two monolayers of LaFeO3 thin film were epitaxially grown on the substrate, and then five monolayers of LaAlO3 thin film were epitaxially grown, and the number of film growth layers was monitored by reflection high energy electron diffractometer (RHEED); the pulsed laser wavelength of the sputtered polycrystalline LaFeO3 ceramic target (99.99%) and single crystal LaAlO3 target (99.99%) in the perovskite phase was 248nm, and the energy density was 1.5J / cm 2 , frequency is 2Hz;

[0085] (4) The sample on which the thin film was grown was placed in a magnetron sputtering chamber, and Ti with a thickness of 20 nm was sputtered on the rough surface of the SrTiO3 substrate as an adhesion layer, and Pt with a thickness of 20 nm was sputtered as a back electrode to obtain a gas detector component.

[0086] Another method for preparing a gas sensor in this embodiment includes the following specific steps:

[0087] (1) SrTiO3 substrate cleaning: The SrTiO3 substrate was ultrasonically cleaned in acetone for 10 min to remove organic impurities on the surface, and then ultrasonically cleaned in anhydrous ethanol for 10 min to remove acetone and other impurities on the surface;

[0088] (2) SrTiO3 substrate etching annealing: The cleaned SrTiO3 substrate was ultrasonically reacted in deionized water for 30 minutes, then etched in BOE solution for 30 seconds, then rinsed in deionized water and the water adsorbed on the surface was blown dry with nitrogen, and the etched substrate was annealed at 950°C for 90 minutes to obtain a Ti-O layer-cut-off SrTiO3 substrate with a high-quality step surface;

[0089] (3) Epitaxial growth of oxide thin films: The annealed SrTiO3 substrate is placed in a pulsed laser deposition chamber and the chamber is evacuated to 10 -8 mbar; then fill the cavity with oxygen to 10 -5mbar; the SrTiO3 substrate was heated to 675°C, and 5 monolayers of LaFeO3 thin film were epitaxially grown on the substrate, and then 15 monolayers of LaAlO3 thin film were epitaxially grown, and the number of film growth layers was monitored by reflection high energy electron diffractometer (RHEED); the pulsed laser wavelength of the sputtered polycrystalline LaFeO3 ceramic target (99.99%) and single crystal LaAlO3 target (99.99%) in the perovskite phase was 248nm, and the energy density was 1J / cm 2 , frequency is 3Hz;

[0090] (4) The sample on which the thin film was grown was placed in a magnetron sputtering chamber, and Ti with a thickness of 20 nm was sputtered on the rough surface of the SrTiO3 substrate as an adhesion layer, and Au with a thickness of 50 nm was sputtered as a back electrode to obtain a gas detector component.

[0091] Example 3

[0092] This embodiment provides a method for measuring gas composition and gas pressure, using the above-mentioned gas sensor components, cooling to below the gas freezing point through a small temperature control platform, and applying a back gate electric field to adsorb solid gas molecules on the surface of the gas sensor;

[0093] The gas sensor components are heated at a constant heating rate using a small temperature control platform. The boiling or sublimation desorption of the gas will cause the carrier concentration of the gas sensor components to change, which in turn leads to a change in the resistance value. The surface temperature and the resistance of the gas sensor components are recorded in real time, and the first-order differential curve of resistance and temperature is plotted. The temperature corresponding to the minimum value of the curve is the boiling point or sublimation temperature of the gas.

[0094] The gas pressure can be estimated by using the boiling point or sublimation temperature and the three-phase diagram of the gas; where: When the gas sensor measures the gas composition and gas pressure, the back gate electric field applied is ≥500V / cm. After the gas sensor applies the back gate electric field at 2K, during the heating process, the R (resistance)-T (temperature) curve and dR / dT (first-order differential of resistance)-T curve of the gas sensor are as follows: Figure 2 As shown in Figure 2, after the gas sensor applies the back gate electric field at different temperatures, the RT curve of the gas sensor during the heating process is as follows: Figure 3 shown.

[0095] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for measuring gas composition and gas pressure using a gas sensor, characterized in that: include: After cooling to below the freezing point of the gas through a small temperature control platform, a back gate electric field is applied to adsorb the solid gas molecules on the surface of the gas sensor; The gas sensor is heated at a constant heating rate using a temperature control platform, the surface temperature and resistance of the gas sensor are recorded in real time, and a first-order differential curve of resistance and temperature is drawn. The temperature corresponding to the minimum value of the curve is the boiling point or sublimation temperature of the gas. Based on the boiling point or sublimation temperature and the three-phase diagram of the gas, the gas pressure is obtained; The applied back gate electric field is ≥500 V / cm; Wherein, the gas sensor comprises: a SrTiO3 substrate, a LaFeO3 film, a LaAlO3 film, an adhesion layer and a back electrode; The SrTiO3 substrate comprises a polished surface and a rough surface; The LaFeO3 film is grown on the polished surface, and the LaAlO3 film is grown on the LaFeO3 film; The rough surface is plated with the adhesion layer and the back electrode, and the back electrode is connected to the temperature control platform.

2. The method for measuring gas composition and gas pressure using a gas sensor according to claim 1, characterized in that: The SrTiO3 substrate is a single-sided polished perovskite phase single crystal SrTiO3 substrate with a first preset thickness and a preset orientation, and the thickness of the SrTiO3 substrate is ≤0.5 mm; The LaFeO3 film is a preset oriented single crystal LaFeO3 film of a perovskite phase with a second preset thickness, and the thickness of the LaFeO3 film is 2-10 monolayers; The LaAlO3 film is a preset oriented single crystal LaAlO3 film of a perovskite phase with a third preset thickness, and the thickness of the LaAlO3 film is 2-15 monolayers; The adhesion layer and the back electrode are metal layers of different elements.

3. The method for measuring gas composition and gas pressure using a gas sensor according to claim 1, characterized in that: The preparation method of the gas sensor comprises: Pre-treating the SrTiO3 substrate; Epitaxially growing an oxide film on the pretreated SrTiO3 substrate; The SrTiO3 substrate on which the oxide film is grown is subjected to magnetron metal sputtering to obtain the gas sensor, and the gas sensor is adhered to a temperature control platform.

4. The method for measuring gas composition and gas pressure using a gas sensor according to claim 3, characterized in that: Pre-treating the SrTiO3 substrate comprises: The SrTiO3 substrate is cleaned, and the cleaned SrTiO3 substrate is subjected to etching and annealing treatment.

5. The method for measuring gas composition and gas pressure using a gas sensor according to claim 4, characterized in that: Cleaning the SrTiO3 substrate comprises: The SrTiO3 substrate is placed in acetone for ultrasonic cleaning to remove organic impurities on the surface of the SrTiO3 substrate, and then ultrasonically cleaned in anhydrous ethanol to remove acetone and other impurities on the surface of the SrTiO3 substrate.

6. The method for measuring gas composition and gas pressure using a gas sensor according to claim 4, characterized in that: The etching annealing treatment of the cleaned SrTiO3 substrate comprises: The cleaned SrTiO3 substrate was ultrasonically reacted in deionized water for 30 minutes, then etched in BOE buffer for 30 seconds, then rinsed in deionized water and the water adsorbed on the surface was blown dry with nitrogen, and the etched substrate was annealed at 950°C for 90 minutes.

7. The method for measuring gas composition and gas pressure using a gas sensor according to claim 3, characterized in that: Epitaxial growth of oxide thin films includes: The pretreated SrTiO3 substrate is placed in a pulsed laser deposition chamber, and the chamber is evacuated to a pressure of less than 10 -7 mbar; then fill the cavity with oxygen to make the pressure in the cavity reach 10 -5 -10 -4 mbar; heating the SrTiO3 substrate to 650-750°C, epitaxially growing 2-10 monolayers of LaFeO3 film on the SrTiO3 substrate, epitaxially growing 2-15 monolayers of LaAlO3 film based on the LaFeO3 film, and monitoring the number of film growth layers by a reflection high-energy electron diffractometer.

8. The method for measuring gas composition and gas pressure using a gas sensor according to claim 3, characterized in that: Performing magnetron metal sputtering includes: The SrTiO3 substrate on which the thin film is grown is placed in a magnetron sputtering chamber, a first element metal with a thickness of ≥5nm is sputtered on the rough surface of the SrTiO3 substrate as an adhesion layer, and then a second element metal with a thickness of ≥5nm is sputtered as a back electrode, wherein the first element metal is different from the second element metal, and the first element metal can enhance the adhesion between the substrate and the second element metal.

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