阅读说明：本技术 一种多孔氮化镓基室温气体传感器的制备方法 (Preparation method of porous gallium nitride-based room temperature gas sensor ) 是由 潘毅 陈熙 沙法·穆罕默德 柯柯 于 2020-12-02 设计创作，主要内容包括：本发明公开了一种多孔氮化镓基室温气体传感器的制备方法,该传感器所用氮化镓薄膜可通过金属有机物化学气相沉积和氢化物气相外延法生长于蓝宝石衬底上,表面经金属催化化学腐蚀法获得孔径可调的纳米微孔,随后经1,2-乙二硫醇(EDT)钝化处理后,利用物理沉积法在表面负载高分散铂(Pt)纳米颗粒。经该方法处理的材料具有比表面积大、活性中心稳定、传质通道多,而且成本较低,易于批量制备等优点。该基于以铂纳米粒子修饰的硫化物钝化多孔GaN材料半导体传感器,可以在室温温区同时检测H-2,H-2S和C-2H-4等多种气体,H-2极限灵敏度可达65％以上。可在物联网(IoT)生态系统中的物理设备广泛应用。(The invention discloses a preparation method of a porous gallium nitride-based room temperature gas sensor, wherein a gallium nitride film used by the sensor can be grown on a sapphire substrate by metal organic chemical vapor deposition and hydride vapor epitaxy, nano micropores with adjustable pore diameters are obtained on the surface by a metal catalytic chemical corrosion method, and then high-dispersion platinum (Pt) nano particles are loaded on the surface by a physical deposition method after passivation treatment of 1, 2-Ethanedithiol (EDT). The material treated by the method has the advantages of large specific surface area, stable active center, more mass transfer channels, lower cost, easy batch preparation and the like. The sulfide-passivated porous GaN material semiconductor sensor based on platinum nanoparticle modification can simultaneously detect H in a room temperature zone 2 ，H 2 S and C 2 H 4 A plurality of gases, H 2 The ultimate sensitivity can reach more than 65%. Physical devices that can be used in an internet of things (IoT) ecosystem are widely used.)

1. A preparation method of a porous gallium nitride-based room temperature gas sensor is characterized by comprising the following steps:

step 1: epitaxially growing a GaN thick film on a sapphire substrate;

step 2: preparing porous gallium nitride on the prepared GaN thick film by using a metal catalytic chemical corrosion method;

and step 3: immersing the prepared porous gallium nitride device into a 1, 2-ethanedithiol solution for passivation;

and 4, step 4: drying the passivated porous gallium nitride device, then transferring the dried porous gallium nitride device into a vacuum evaporation chamber, and depositing trace Pt nano particles with the distribution ratio of 1% -10% on the surface of the device;

and 5: preparing an electrode with a certain thickness on the surface of the prepared Pt nano particle device by adopting a hard mask method;

step 6: and packaging the device, testing the gas-sensitive performance of the porous gallium nitride in a mixed atmosphere, and calibrating characteristic parameters to obtain the gallium nitride-based gas sensor.

2. The method for preparing a porous GaN-based room temperature gas sensor according to claim 1, wherein in step 1, a GaN thick film is grown by metal organic chemical vapor deposition or hydride vapor phase epitaxy, and the resistivity of the GaN layer is lower than 0.05 Ω -cm; the thickness of the GaN film is 3 to 50 μm.

3. The method for preparing a porous gallium nitride-based room temperature gas sensor according to claim 1, wherein in the step 2, porous gallium nitride is prepared, a GaN sample is subjected to ultrasonic treatment in acetone, and is cleaned with isopropanol for at least 5 min; sputtering and depositing a thin platinum catalyst layer on the sample, then immersing the sample in nitric acid, standing the sample at the temperature of 60-80 ℃ for 10-20 min, and washing the sample with deionized water and methanol; and then immersing the steel plate into the steel plate in a mass ratio of 2: 1: 2H₂O₂/HF/CH₃Etching the mixture in the OH mixed solution for 25-30 min under the irradiation of ultraviolet rays, wherein the porosity is 50-60%.

4. The method for preparing a porous GaN-based room temperature gas sensor according to claim 1, wherein in the step 3, the passivation process is to immerse the substrate with the prepared porous GaN into HF: H in a volume ratio₂And (3) washing the mixture for 15-60 s in a hydrofluoric acid solution with the ratio of O1: 5-1: 10 by using deionized water for 10-20 s, soaking the mixture into a 1, 2-ethanedithiol solution for not less than 5min, washing the mixture by using ethanol, and drying the mixture by using nitrogen.

5. The method for preparing a porous gallium nitride-based room temperature gas sensor according to claim 4, wherein the mass concentration of the 1, 2-ethanedithiol solution is more than 99%.

6. The method for preparing a porous gallium nitride-based room temperature gas sensor according to claim 1, wherein in the step 4, the passivated porous gallium nitride device is placed in a vacuum degree of 10^-9～10^-7And depositing 5-20 s in a vacuum equipment cavity with mbar within the temperature range of 1200-1500 ℃, and depositing Pt nano particles with the diameter less than 10nm on the surface of the device.

7. The method for preparing a porous gallium nitride-based room temperature gas sensor according to claim 1, wherein in the step 5, the thickness of the prepared electrode is 50-200 nm, and the electrode material is Pt/Ni, Pt/Cr, Pt/Ti, Au/Ni, Au/Cr or Au/Ti.

8. A method for preparing a porous GaN-based room temperature gas sensor according to any of claims 1-7, wherein the gas concentration of H is 30-200ppm at 23-60 deg.C₂、H₂S and C₂H₄H for testing gallium nitride-based gas sensor in mixed atmosphere₂The sensitivity response is not lower than 65%.

Technical Field

The invention relates to the technical field of gas sensitive materials and gas sensors, in particular to a preparation method of a porous gallium nitride-based room temperature gas sensor.

Background

A key requirement in the development of gas sensor systems is that they have the ability to identify and detect a wide variety of low concentration gases when operated in a dynamic modeFor medical, industrial, security and even home applications and to be quickly identified. Wherein H₂，H₂S and C₂H₄Is a common pollutant gas and has serious risks to human health. In such a situation, a unified gas sensor with excellent selectivity, high sensitivity, fast response, low gas operable concentration and cost effectiveness is an urgent necessity. In addition, a wide detection range is necessary, and among them, the development of gas sensors for these gases at 10 to 1000ppm has attracted a wide attention. Therefore, rapid and efficient monitoring and detection of gases has become an urgent problem to be solved.

A variety of techniques have been used to detect and monitor these contaminants, including gas chromatography-mass spectrometry, electrochemical biosensors, optical methods, FTIR analysis, etc., but these methods all require later analysis in a laboratory or research facility, are time consuming, slow to detect, and are relatively costly.

GaN is taken as a representative of a third-generation semiconductor, and the direct band gap wide bandgap semiconductor material has a continuously variable direct band gap between 1.9 and 6.2eV, also has the characteristics of large critical breakdown voltage, high electron mobility, acid and alkali resistance, high temperature resistance and the like, and can meet the requirements of next-generation electronic equipment on high-power, high-frequency, small-volume and high-temperature work of a power device. At present, a gas sensor using GaN as a gas sensitive material is mainly a silicon-based sensor, and the gas sensor is limited by factors of sensitivity, power consumption and detection limit, and is difficult to maintain the reliability of the performance of the gas sensor in application fields with higher sensitivity requirements (such as medical fields and environmental detection) or under more severe conditions (such as multi-component atmosphere and high temperature).

As a method of improving gas sensing performance, the introduction of a porous structure generally improves sensing performance with significantly faster response and higher sensitivity. Because the gallium nitride is generally epitaxially grown on the foreign substrate when growing the gallium nitride, higher dislocation density and larger stress are brought to the GaN epitaxially grown, and the dislocation density in the GaN can be effectively reduced by the porous structure, and the stress influence brought by the heterogeneous growth is relieved, so that the crystal quality of the GaN epitaxially grown by the heterogeneous method can be improved, and the gas-sensitive detection performance is improved.

Wet sulfur passivation is one of the effective means to reduce the surface state of semiconductor materials. Currently, the passivation used for wet sulfur passivation is mainly Na₂S，(NH₄)₂S，CH₃CSNH₂Etc. but using (NH)₄)₂Toxic H is easily generated during S passivation₂S gas, with Na₂S also has the problem of sodium ion pollution, and other sulfur-containing organic matters require long passivation time, and require several hours to complete passivation. The 1, 2-Ethanedithiol (EDT) organic thiol compound with short carbon chain is used as a passivation solution, so that the cost is low, the time is short, only 5 minutes are needed, harmful substances are not generated in the passivation process, and the adverse effects of chemically adsorbed hydroxyl, oxide and dangling bonds can be greatly reduced. A sulfide solution is used for soaking a semiconductor material, S atoms and semiconductor surface atoms form covalent bonds, so that the surface state density is reduced, the corresponding sulfide layer can inhibit the surface from being oxidized again, and the S atoms form firm covalent bonds and can be used as ligands to be connected with metal ion promoters.

Aiming at the gallium nitride gas sensor, the requirements of high sensitivity, low power consumption and low detection limit are still difficult to meet only by using a single modification treatment method, so that a composite method can be adopted, the advantages of a porous structure, passivation modification and precious metal nanoparticle modification methods are integrated, and the gas-sensitive performance of the gallium nitride sensor is improved.

Disclosure of Invention

In order to solve the defects in the prior art, the invention aims to provide a preparation method of a gallium nitride-based gas sensor, which combines a plurality of methods for improving gas-sensitive performance together, utilizes a metal catalytic chemical corrosion method to etch gas-sensitive material gallium nitride to obtain a porous structure, uses an EDT solution to passivate the porous gallium nitride obtained by etching, and then deposits Pt nano-particles on the surface of a passivated sample to modify, thereby realizing the purpose of carrying out modification on a plurality of gases (such as H)₂，H₂S and C₂H₄) Showing significant selectivity as well as sensitivity.

The invention is realized by the following technical scheme.

The invention provides a preparation method of a gallium nitride-based gas sensor, which comprises the following steps:

step 1: epitaxially growing a GaN thick film on a sapphire substrate;

step 2: preparing porous gallium nitride on the prepared GaN thick film by using a metal catalytic chemical corrosion method;

and step 3: immersing the prepared porous gallium nitride device into a 1, 2-ethanedithiol solution for passivation;

and 4, step 4: drying the passivated porous gallium nitride device, then transferring the dried porous gallium nitride device into a vacuum evaporation chamber, and depositing trace Pt nano particles with the distribution ratio of 1% -10% on the surface of the device;

and 5: preparing an electrode with a certain thickness on the surface of the prepared Pt nano particle device by adopting a hard mask method;

step 6: and packaging the device, testing the gas-sensitive performance of the porous gallium nitride in a mixed atmosphere, and calibrating characteristic parameters to obtain the gallium nitride-based gas sensor.

With respect to the above technical solutions, the present invention has a further preferable solution:

preferably, in the step 1, a thick GaN film is grown by a metal organic chemical vapor deposition method or a hydride vapor phase epitaxy method, and the resistivity of the GaN layer is lower than 0.05 Ω · cm; the thickness of the GaN film is 3 to 50 μm.

Preferably, in the step 2, porous gallium nitride is prepared, a GaN sample is subjected to ultrasonic treatment in acetone, and is washed with isopropanol for at least 5 min; sputtering and depositing a thin platinum catalyst layer on the sample, then immersing the sample in nitric acid, standing the sample at the temperature of 60-80 ℃ for 10-20 min, and washing the sample with deionized water and methanol; and then immersing the steel plate into the steel plate in a mass ratio of 2: 1: 2H₂O₂/HF/CH₃Etching the mixture in the OH mixed solution for 25-30 min under the irradiation of ultraviolet rays, wherein the porosity is 50-60%.

Preferably, in the step 3, the passivation process is that the prepared substrate of the porous gallium nitride is immersed into HF to H in a volume ratio₂Removing surface oxides in hydrofluoric acid solution with the ratio of O1: 5-1: 10 for 15-60 s, washing with deionized water for 10-20 s, and immersing in the solution with the concentrationDissolving more than 99% 1, 2-ethanedithiol in the solution for not less than 5min, washing with ethanol, and drying with nitrogen gas.

Preferably, in the step 4, the passivated porous gallium nitride device is placed in a vacuum degree of 10^-9～10^{- 7}And depositing 5-20 s in a vacuum equipment cavity with mbar within the temperature range of 1200-1500 ℃, and depositing Pt nano particles with the diameter less than 10nm on the surface of the device.

Preferably, in the step 5, the thickness of the prepared electrode is 50-200 nm, and the electrode material is Pt/Ni, Pt/Cr, Pt/Ti, Au/Ni, Au/Cr or Au/Ti.

Preferably, the hydrogen concentration is 30-200ppm H at 23-60 deg.C₂、H₂S and C₂H₄H for testing gallium nitride-based gas sensor in mixed atmosphere₂The sensitivity response is not lower than 65%.

Due to the adoption of the technical scheme, the invention has the following beneficial effects:

1. according to the invention, a metal-assisted chemical etching method is adopted to prepare the porous structure on the gallium nitride substrate, so that dislocation caused by heteroepitaxy is reduced, the stress of heteroepitaxy growth is relieved, the quality of gallium nitride crystals is improved, meanwhile, the specific surface area of the gas-sensitive material is improved due to high porosity, namely, the effective area is increased, and the sensitivity of the gas-sensitive material is improved.

2. According to the invention, the surface of gallium nitride is passivated by using 1, 2-ethanedithiol, and a covalent bond is formed between a sulfur atom and the surface of a semiconductor, so that surface defects are removed, thereby reducing the surface state density of the material, reducing the adsorption energy, resulting in increased sensitivity and lower detection limit of the material, and the 1, 2-ethanedithiol passivation material is easy to obtain, short in passivation time and low in preparation cost.

3. According to the invention, platinum nanoparticles are used for modifying the surface of gallium nitride, so that gas catalytic sites are increased, decomposition of hydrogen-containing gas into atoms is promoted, and the atoms are adsorbed on the surface, and the sensitivity of the material is improved.

4. The invention combines two methods for improving gas-sensitive performance, namely surface sulfur passivation of gas-sensitive material gallium nitride and platinum nanoparticle loading, the platinum nanoparticle can be combined with gallium and sulfide, and hydrogen is detected by hydrogenation and vulcanization catalyzed by metal sulfide. The hydrogen atoms adsorbed at the platinum/passivated porous gallium nitride interface form a dipole layer, lowering the barrier height, which reaction makes the passivation layer more conductive and raises the fermi level. Sensors made with this material will exhibit better hydrogen response.

5. The sulfide-passivated porous GaN material prepared by the invention and modified by the platinum nanoparticles can simultaneously detect H in a room temperature zone₂，H₂S and C₂H₄And the ultimate sensitivity can reach 30 ppm. And can be used at different temperatures and gas concentrations for H₂Is very sensitive to the response of H₂The detection has wide application prospect.

6. The invention has short etching time and passivation time, low cost and easy realization.

7. The material treated by the method has the advantages of large specific surface area, stable active center, more mass transfer channels, lower cost, easy batch preparation and the like. The sensor preparation is compatible with semiconductor technology and can be widely applied to physical equipment in a crop networking (IoT) ecosystem.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention:

FIG. 1 is a cross-sectional view of a device of porous GaN after metal-assisted chemical etching, 1, 2-ethanedithiol passivation, and platinum nanoparticle modification;

FIG. 2 is a fabrication flow chart for preparing a gas sensitive sensing material;

FIG. 3 is a graph of the gas sensitive material at room temperature for concentrations H of 30ppm and 200ppm, respectively₂，H₂S and C₂H₄(ii) a response of (d);

FIG. 4 is 50ppm H at room temperature₂、H₂S and C₂H₄Actual response and recovery time of the gas.

Detailed Description

The present invention will now be described in detail with reference to the drawings and specific embodiments, wherein the exemplary embodiments and descriptions of the present invention are provided to explain the present invention without limiting the invention thereto.

The invention discloses a preparation method of a gallium nitride-based gas sensor, which comprises the following steps:

step 1: a GaN thick film 2 is epitaxially grown on a sapphire substrate 1.

Epitaxially growing a GaN thick film, wherein n-type natural doping of the GaN thick film is derived from trace residual Cl in the growth process, and the resistivity of the GaN layer is lower than 0.05 omega cm; the growth method may be Metal Organic Chemical Vapor Deposition (MOCVD) and Hydride Vapor Phase Epitaxy (HVPE); the thickness of the GaN film is 3 to 50 μm.

Step 2: porous gallium nitride was prepared on the prepared GaN thick film using a metal-catalyzed chemical etching method to obtain a porous layer 3. Carrying out ultrasonic treatment on the GaN sample in acetone, and cleaning for at least 5min by using isopropanol; sputtering and depositing a thin platinum catalyst layer on the sample, then immersing the sample in nitric acid, standing the sample at the temperature of 60-80 ℃ for 10-20 min, and washing the sample with deionized water and methanol; the GaN sample is immersed in a solution with the mass ratio of 2: 1: 2H₂O₂/HF/CH₃Etching the mixture in the OH mixed solution for 25-30 min under the irradiation of ultraviolet rays, wherein the porosity is 50-60%.

And step 3: immersing the prepared porous gallium nitride device into a 1, 2-ethanedithiol solution with the concentration of more than 99% for passivation to form a passivation layer 4; the passivation process is that the prepared substrate of the porous gallium nitride is immersed into HF to H according to the volume ratio₂Removing surface oxides in hydrofluoric acid solution with the ratio of O1: 5-1: 10 for 15-60 s, washing with deionized water for 10-20 s, immersing in 1, 2-ethanedithiol solution with the concentration of more than 99% for not less than 5min, washing with ethanol, and drying with nitrogen.

And 4, step 4: putting the passivated porous gallium nitride device into a vacuum degree of 10^-9～10^-7And depositing 5-20 s in a vacuum equipment cavity with mbar within the temperature range of 1200-1500 ℃, and depositing Pt nano particles with the diameter less than 10nm on the surface of the device.

And 5: preparing an electrode with a certain thickness by using a magnetron sputtering system through a hard mask in the device prepared in the step 4; preparing a nano electrode 6 with the thickness of 50-200 nm, wherein the electrode material is Pt/Ni, Pt/Cr, Pt/Ti, Au/Ni, Au/Cr and Au/Ti.

Step 6: packaging the device with gas concentration of 30-200ppm of H at 23-60 deg.C₂，H₂S，C₂H₄And testing the gas-sensitive performance of the Pt/sulfide porous GaN in the mixed atmosphere, and calibrating characteristic parameters to obtain the gallium nitride-based gas sensor.

The sensor has a gas concentration of 30-200ppm and a temperature of 23-60 ℃ of H not less than 65%₂Ultimate sensitivity response.

The effects of the present invention will be further described below by way of specific examples.

Example 1

Step 1: epitaxially growing an n-type GaN thick film with the thickness of 30 mu m on the sapphire substrate by using a hydride vapor phase epitaxy method; the n-type natural doping comes from trace Cl residue in the growth process, and the resistivity of the GaN layer is lower than 0.05 omega cm.

Step 2: preparing porous gallium nitride on the prepared GaN thick film by using a metal catalytic chemical corrosion method; carrying out ultrasonic treatment on the GaN sample in acetone, and cleaning for at least 5min by using isopropanol; sputtering and depositing a 10nm thin-layer platinum catalyst layer on the sample, then immersing the sample in nitric acid, standing the sample at 65 ℃ for 10min, and washing the sample with deionized water and methanol; GaN samples were immersed according to 2: 1: 2 mass ratio of H₂O₂/HF/CH₃Etching in OH solution under ultraviolet irradiation for 30min to obtain 55% porosity.

And step 3: immersing the prepared porous gallium nitride device into a 1, 2-ethanedithiol solution with the concentration of more than 99% for passivation; immersing the prepared substrate of porous gallium nitride into HF to H according to the volume ratio₂Removing surface oxide from O1: 5 hydrofluoric acid solution for 50s, washing with deionized water for 20s, soaking in 1, 2-ethanedithiol solution with concentration of more than 99% for 5min, washing with ethanol, and drying with nitrogen.

And 4, step 4: drying the passivated porous gallium nitride device, and then introducing the dried porous gallium nitride device into a vacuum degree of 10^-9And (3) depositing 15s at 1210 ℃ in a vacuum equipment cavity with mbar, and depositing Pt nano particles with the diameter of less than 10nm on the surface of the device.

And 5: and 4, preparing a nano electrode with the thickness of 100nm by using a magnetron sputtering system through a hard mask, wherein the electrode material is Pt/Ni.

Step 6: and packaging the device. At 23 ℃ and at a gas concentration of 30ppm H₂，H₂S，C₂H₄And testing the gas-sensitive performance of the Pt/sulfide porous GaN in the mixed atmosphere, and calibrating characteristic parameters to obtain the gallium nitride-based gas sensor.

Fig. 1 and fig. 2 show a device schematic diagram of a gas sensor and a preparation flow thereof.

In this example, the embodiment uses SEM for morphological studies, and statistical information of surface porosity was extracted from a large number of SEM images by SEM analysis software, and the porosity was estimated to be 55%. The chemical composition of the virgin and EDT-treated Pt/porous GaN was analyzed by X-ray photoelectron spectroscopy (XPS) at room temperature, and characteristic peaks from the S elements in two different bonding states, Ga-S-C and Ga-S-H, respectively, were detected.

In this example, the temperature has some effect on the sensitivity of various gaseous concentrations of Pt/sulfide porous GaN sensor devices. At three temperatures of 23 ℃, 40 ℃, 60 ℃ and different concentrations of H₂，H₂S and C₂H₄In a gas, the response of the sample increases with increasing temperature. At a temperature of 23 ℃ H₂The most pronounced response of (C), and at 60 ℃ H₂The response of S is obviously increased. The temperature rise sensitivity is improved, and when the gas molecules are not absorbed in the moving area of the sample any more, the temperature reaches a saturation stage. And H₂S and C₂H₄In contrast, sample pair H₂The response of the gas is higher.

In this example, for H₂The sample response increases dramatically as its concentration increases from 30ppm to 200ppm, later saturating with the maximum signal. The samples showed a significant response to H2 at 30ppm at 23 ℃. Before passivation, under different gas concentrations (30-300 ppm), the response range is 40% -59%; after passivation, the device response increased to 90% at a concentration of 130ppm H2.

Example 2

Step 1: epitaxially growing a 50-micrometer n-type GaN thick film on a sapphire substrate by using a hydride vapor phase epitaxy method; the n-type natural doping comes from trace Cl residue in the growth process, and the resistivity of the GaN layer is lower than 0.05 omega cm.

Step 2: preparing porous gallium nitride on the prepared GaN thick film by using a metal catalytic chemical corrosion method; carrying out ultrasonic treatment on the GaN sample in acetone, and cleaning for at least 5min by using isopropanol; sputtering and depositing a 10nm thin-layer platinum catalyst layer on the sample, then immersing the sample in nitric acid, standing the sample at 80 ℃ for 10min, and washing the sample with deionized water and methanol; GaN samples were immersed according to 2: 1: 2 mass ratio of H₂O₂/HF/CH₃Etching in OH solution under ultraviolet irradiation for 30min to obtain porosity of 58%.

And step 3: immersing the prepared porous gallium nitride device into a 1, 2-ethanedithiol solution with the concentration of more than 99% for passivation; immersing the prepared substrate of porous gallium nitride into HF to H according to the volume ratio₂Removing surface oxide in hydrofluoric acid solution of O1: 10 for 15s, washing with deionized water for 10s, soaking in 1, 2-ethanedithiol solution with concentration of more than 99% for 10min, washing with ethanol, and drying with nitrogen.

And 4, step 4: drying the passivated porous gallium nitride device, and then transferring the dried porous gallium nitride device into a vacuum evaporation chamber with the vacuum degree of 10^-8In a vacuum equipment cavity with mbar, depositing for 10s at 1300 ℃, and depositing trace Pt nano particles with the diameter less than 10nm on the surface of the device.

And 5: in the device prepared in the step 4, an electrode with the thickness of 120 nanometers is prepared through a hard mask by using a magnetron sputtering system, and the electrode material is Au/Ni.

Step 6: and packaging the device. At 25 ℃ in a gas concentration of 30ppm of H₂，H₂S，C₂H₄And testing the gas-sensitive performance of the Pt/sulfide porous GaN in the mixed atmosphere, and calibrating characteristic parameters to obtain the gallium nitride-based gas sensor.

In this example, the porosity was evaluated as 58%.

In this example, for H₂The response of the sample increases sharply when the concentration increases from 30ppm to 200ppm, and then increases with the maximum concentrationThe large signal is saturated. The samples showed a significant response to H2 at 30ppm at 23 ℃. Before passivation, under different gas concentrations (30-300 ppm), the response range is 40% -59%; after passivation, H₂At a concentration of 30ppm, the device response increased to 65%. The response of the three gases at room temperature is shown in figure 3.

Example 3

Step 1: epitaxially growing a 40-micron n-type GaN thick film on a sapphire substrate by using a hydride vapor phase epitaxy method; the n-type natural doping comes from trace Cl residue in the growth process, and the resistivity of the GaN layer is lower than 0.05 omega cm.

Step 2: preparing porous gallium nitride on the prepared GaN thick film by using a metal catalytic chemical corrosion method; carrying out ultrasonic treatment on the GaN sample in acetone, and cleaning for at least 5min by using isopropanol; sputtering and depositing a 10nm thin-layer platinum catalyst layer on the sample, then immersing the sample in nitric acid, standing the sample at 70 ℃ for 10min, and washing the sample with deionized water and methanol; GaN samples were immersed according to 2: 1: 2 mass ratio of H₂O₂/HF/CH₃Etching in OH solution under ultraviolet irradiation for 30min to obtain a porosity of 60%.

And step 3: immersing the prepared porous gallium nitride device into a 1, 2-ethanedithiol solution with the concentration of more than 99% for passivation; immersing the prepared substrate of porous gallium nitride into HF to H according to the volume ratio₂Removing surface oxide in O1: 6 hydrofluoric acid solution for 60s, washing with deionized water for 10s, soaking in 1, 2-ethanedithiol solution with concentration of more than 99% for 8min, washing with ethanol, and drying with nitrogen.

And 4, step 4: drying the passivated porous gallium nitride device, and then introducing the dried porous gallium nitride device into a vacuum degree of 10^-9And in a vacuum equipment cavity with mbar, depositing for 20s at the temperature of 1200 ℃, and depositing Pt nano particles with the diameter of less than 10nm on the surface of the device.

And 5: in the device prepared in step 4, an electrode with the thickness of 90 nanometers is prepared through a hard mask by using a magnetron sputtering system, and the electrode material is Pt/Cr.

Step 6: and packaging the device. At 23 ℃ and at a gas concentration of 30ppm H₂，H₂S，C₂H₄Testing of Pt/sulfidation in Mixed atmospheresAnd (3) the gas-sensitive performance of the porous GaN is measured, and characteristic parameters are calibrated, so that the gallium nitride-based gas sensor is obtained.

In this example, the porosity was evaluated as 60%.

In this example, for H₂The sample response increases dramatically as its concentration increases from 30ppm to 200ppm, later saturating with the maximum signal. Sample at 60 ℃ and 30ppm for H₂A significant response was shown. Before passivation, under different gas concentrations (30-300 ppm), the response range is 55% -76%; after passivation, H₂At a concentration of 60ppm, the device response increased to 86%.

Example 4:

step 1: epitaxially growing a 3-micron n-type GaN thick film on a sapphire substrate by using a Metal Organic Chemical Vapor Deposition (MOCVD) method; the n-type natural doping comes from trace Cl residue in the growth process, and the resistivity of the GaN layer is lower than 0.05 omega cm.

Step 2: preparing porous gallium nitride on the prepared GaN thick film by using a metal catalytic chemical corrosion method; carrying out ultrasonic treatment on the GaN sample in acetone, and cleaning for at least 5min by using isopropanol; sputtering and depositing a 10nm thin-layer platinum catalyst layer on the sample, then immersing the sample in nitric acid, standing the sample at 60 ℃ for 20min, and washing the sample with deionized water and methanol; GaN samples were immersed according to 2: 1: 2 mass ratio of H₂O₂/HF/CH₃Etching in OH solution under ultraviolet irradiation for 25min to obtain a porosity of 53%.

And step 3: immersing the prepared porous gallium nitride device into a 1, 2-ethanedithiol solution with the concentration of more than 99% for passivation; immersing the prepared substrate of porous gallium nitride into HF to H according to the volume ratio₂Removing surface oxide in hydrofluoric acid solution of O1: 8 for 30s, washing with deionized water for 10s, soaking in 1, 2-ethanedithiol solution with concentration of more than 99% for 5min, washing with ethanol, and drying with nitrogen.

And 4, step 4: putting the passivated porous gallium nitride device into a vacuum degree of 10^-8And depositing for 10s at 1290 ℃ in a vacuum equipment cavity with mbar, and depositing Pt nano particles with the diameter of less than 10nm on the surface of the device.

And 5: in the device prepared in step 4, an electrode 6 with a thickness of 80 nm is prepared by a magnetron sputtering system through a hard mask, and the electrode material is Au/Ti.

Step 6: and packaging the device. At 25 ℃ in a gas concentration of 200ppm of H₂，H₂S，C₂H₄And testing the gas-sensitive performance of the Pt/sulfide porous GaN in the mixed atmosphere, and calibrating characteristic parameters to obtain the gallium nitride-based gas sensor.

In this example, the porosity was evaluated as 53%.

In this example, the sample concentration was 200ppm H at 25 ℃₂，H₂S and C₂H₄The gas was subjected to a 10 minute selectivity test. At 200ppm of H₂，H₂S and C₂H₄The recorded responses of the samples under gas were 1.80, 1.50 and 1.04, respectively, to H₂Has higher sensitivity to C₂H₄The sensitivity of the gas is low. In detecting H₂The gas response rises sharply; gas flow from H₂Switch to H₂After S, the response will suddenly rise first, after a short time interval, for H₂The response of S becomes smooth and lasts for 10 minutes; finally, C is detected at constant temperature and concentration₂H₄The gas shows a weaker response. Sensor H₂The response time is 34s, the recovery time is 101s, and the device response is 80%

Example 5:

step 1: epitaxially growing an n-type GaN thick film of 5 μm on a sapphire substrate by using a Metal Organic Chemical Vapor Deposition (MOCVD) method; the n-type natural doping comes from trace Cl residue in the growth process, and the resistivity of the GaN layer is lower than 0.05 omega cm.

Step 2: preparing porous gallium nitride on the prepared GaN thick film by using a metal catalytic chemical corrosion method; carrying out ultrasonic treatment on the GaN sample in acetone, and cleaning for at least 5min by using isopropanol; sputtering and depositing a 10nm thin-layer platinum catalyst layer on the sample, then immersing the sample in nitric acid, standing the sample at 75 ℃ for 15min, and washing the sample with deionized water and methanol; GaN samples were immersed according to 2: 1: 2 mass ratio of H₂O₂/HF/CH₃Etching in OH solution under ultraviolet irradiation for 25min,the porosity was 53%.

And step 3: immersing the prepared porous gallium nitride device into a 1, 2-ethanedithiol solution with the concentration of more than 99% for passivation; immersing the prepared substrate of porous gallium nitride into HF to H according to the volume ratio₂Removing surface oxide from O1: 7 hydrofluoric acid solution for 45s, washing with deionized water for 20s, soaking in 1, 2-ethanedithiol solution with concentration of more than 99% for 8min, washing with ethanol, and drying with nitrogen.

And 4, step 4: drying the passivated porous gallium nitride device, transferring the dried porous gallium nitride device into a vacuum evaporation chamber, and keeping the vacuum degree at 10^-7And in a vacuum equipment cavity with mbar, depositing 5s at the temperature of 1390 ℃, and depositing Pt nano particles with the diameter of less than 10nm on the surface of the device.

And 5: in the device prepared in step 4, an electrode 6 with a thickness of 50 nm was prepared through a hard mask using a magnetron sputtering system, and the electrode material was Au/Cr.

Step 6: and packaging the device. At 60 ℃ in a gas concentration of 30ppm of H₂，H₂S，C₂H₄And testing the gas-sensitive performance of the Pt/sulfide porous GaN in the mixed atmosphere, and calibrating characteristic parameters to obtain the gallium nitride-based gas sensor.

In this example, the porosity was evaluated as 53%.

In this example, the sample concentration was 30ppm H at 60 ℃₂，H₂S and C₂H₄The gas was subjected to a 10 minute selectivity test. At 50ppm of H₂，H₂S and C₂H₄The recorded responses of the samples under gas were 2.00, 1.50 and 1.07 respectively, for H₂Has higher sensitivity to C₂H₄The sensitivity of the gas is low. In detecting H₂The gas response rises sharply; gas flow from H₂Switch to H₂After S, the response will suddenly rise first, after a short time interval, for H₂The response of S becomes smooth and lasts for 10 minutes; finally, C is detected at constant temperature and concentration₂H₄The gas shows a weaker response. Sensor H₂The response time was 41s, the recovery time was 108s, and the device response was 91%.

Example 6:

step 1: epitaxially growing a 4-micron n-type GaN thick film on a sapphire substrate by using a Metal Organic Chemical Vapor Deposition (MOCVD) method; the n-type natural doping comes from trace Cl residue in the growth process, and the resistivity of the GaN layer is lower than 0.05 omega cm.

Step 2: preparing porous gallium nitride on the prepared GaN thick film by using a metal catalytic chemical corrosion method; carrying out ultrasonic treatment on the GaN sample in acetone, and cleaning for at least 5min by using isopropanol; sputtering and depositing a 10nm thin-layer platinum catalyst layer on the sample, then immersing the sample in nitric acid, standing the sample at 60 ℃ for 10min, and washing the sample with deionized water and methanol; GaN samples were immersed according to 2: 1: 2 mass ratio of H₂O₂/HF/CH₃Etching in OH solution under ultraviolet irradiation for 30min to obtain porosity of 58%.

And step 3: immersing the prepared porous gallium nitride device into a 1, 2-ethanedithiol solution with the concentration of more than 99% for passivation; immersing the prepared substrate of porous gallium nitride into HF to H according to the volume ratio₂Removing surface oxide from hydrofluoric acid solution O1:9 for 25s, washing with deionized water for 10s, soaking in 1, 2-ethanedithiol solution with concentration of 99% or more for 5min, washing with ethanol, and drying with nitrogen.

And 4, step 4: drying the passivated porous gallium nitride device, transferring the dried porous gallium nitride device into a vacuum evaporation chamber, and keeping the vacuum degree at 10^-8And (3) depositing 12s at 1300 ℃ in a vacuum equipment cavity with mbar, and depositing Pt nano particles with the diameter of less than 10nm on the surface of the device.

And 5: in the device prepared in step 4, an electrode 6 with a thickness of 200nm was prepared through a hard mask using a magnetron sputtering system, and the electrode material was Pt/Ni.

Step 6: and packaging the device. At 23 ℃ and at a gas concentration of 30ppm H₂，H₂S，C₂H₄And testing the gas-sensitive performance of the Pt/sulfide porous GaN in the mixed atmosphere, and calibrating characteristic parameters to obtain the gallium nitride-based gas sensor.

In this example, the porosity was evaluated as 58%.

In this example, as shown in FIG. 4, the sample pair concentration was 30pp at room temperatureH of m₂，H₂S and C₂H₄The gas was subjected to a 10 minute selectivity test. At 30ppm of H₂，H₂S and C₂H₄The recorded responses of the samples under gas were 1.60, 1.20 and 1.01, respectively, to H₂Has higher sensitivity to C₂H₄The sensitivity of the gas is low. In detecting H₂The gas response rises sharply; gas flow from H₂Switch to H₂After S, the response will suddenly rise first, after a short time interval, for H₂The response of S becomes smooth and lasts for 10 minutes; finally, C is detected at constant temperature and concentration₂H₄The gas shows a weaker response. Sensor H₂The response time was 47s, the recovery time was 113s, and the device response was 69%.

The present invention is not limited to the above-mentioned embodiments, and based on the technical solutions disclosed in the present invention, those skilled in the art can make some substitutions and modifications to some technical features without creative efforts according to the disclosed technical contents, and these substitutions and modifications are all within the protection scope of the present invention.