Preparation method of microwave plasma method self-assembled gallium oxide nanowire material as well as product and application of microwave plasma method self-assembled gallium oxide nanowire material

Abstract

The invention provides a preparation method of a microwave plasma method self-assembled gallium oxide nanowire as well as a product and application of the microwave plasma method self-assembled gallium oxide nanowire, liquid gallium is subjected to microwave plasma treatment and self-assembled growth on a silicon wafer substrate by adopting microwave plasma under a certain discharge power condition, and a gallium oxide nanowire material is prepared. The gallium oxide nanowire has obvious field effect transistor electrical properties and shows n-type semiconductor characteristics. When the gallium oxide nanowire is applied to a gas sensor material, the conductivity of the gallium oxide nanowire is increased under the conditions of high temperature and high O2 concentration, and the gallium oxide nanowire has good sensing performance on high-temperature O2. The preparation method for preparing the gallium oxide nanowire depends on spontaneous formation, other auxiliary materials are not added, and a new way for preparing the gallium oxide nanowire is provided.

Description

Technical Field

[0001] The present invention relates to the technical field of gas sensor materials, and in particular to a method for preparing a microwave plasma self-assembled gallium oxide nanowire material, and its products and applications. Specifically, a method for preparing a one-dimensional gallium oxide nanowire material for a sensor is disclosed. Background Art

[0002] Nano-metal oxide gas sensors are a hot topic in gas sensor research today. Nano-metal oxide gas sensors use the high specific surface area and high activity of nano-materials to detect various toxic, harmful or flammable and explosive gases based on the changes in conductivity caused by the adsorption and desorption of oxidizing or reducing gases. They mainly include simple nano-metal oxides such as ZnO, SnO2, Fe2O3 and some composite metal oxides. Among them, gallium oxide Ga2O3 materials occupy an important position. The research on gallium oxide materials is helpful to solve the basic problems of internal carrier concentration, carrier lifetime, carrier mechanism and gallium oxide doping of gas-sensitive materials.

[0003] β-Gallium oxide has the advantages of low cost, high sensitivity and good sensing performance; especially β-Gallium oxide nanowire material, first of all, it has a very large contact interface, providing a large number of gas channels, thereby greatly improving the sensitivity; second, the one-dimensional size structure reduces the volume of the sensor and reduces the operating temperature of the sensor, so it has a good application in the field of gas-sensitive detectors. Chinese invention patent application CN202111195016.9 discloses a method for preparing gallium oxide nanowires. The invention patent adopts the magnetron sputtering technology of physical vapor deposition, and uses gallium oxide to lose oxygen in an environment of 400-600°C, so that gallium condenses on the buffer layer for self-catalytic growth to become a nanowire material; it solves the problem of low reactant utilization, and at the same time, there is no need to introduce precious metal catalysts such as Au, which improves the preparation efficiency of nanowires, and the prepared gallium oxide nanowires have good adhesion. Despite great progress, in order to improve the quantum size confinement effect, the preparation of gallium oxide nanowires has become more and more sophisticated, and how to quickly and completely prepare gallium oxide nanowires has always been a huge challenge.

[0004] Plasma is different from solid, liquid and gaseous states. It is called the fourth state of matter. It refers to a state of matter aggregation that contains enough free electrons, negative ions and positrons, and charged particles with approximately equal charge numbers. Microwave plasma is a form of gas discharge that converts microwave energy into the internal energy of gas molecules, excites and ionizes them, and produces plasma. A small amount of electrons in the gas are accelerated by the microwave electric field and then inelastically collide with gas molecules to ionize the gas. Under the condition of appropriate microwave output power, the gas is broken down to achieve continuous discharge, thereby generating microwave plasma.

[0005] The present invention provides a preparation method of self-assembled gallium oxide nanowires by microwave plasma method, and its products and applications. The gallium oxide nanowire material is prepared by microwave plasma treatment of liquid gallium with a silicon wafer as a reaction substrate under certain discharge power conditions. The gallium oxide nanowire has obvious field effect transistor electrical properties and exhibits n-type semiconductor characteristics. When applied to gas sensor materials, the conductivity of the gallium oxide nanowire increases under high temperature and high O2 concentration conditions, showing good sensing performance for high-temperature O2. The preparation method prepares gallium oxide nanowires by spontaneous formation without adding other auxiliary materials, which provides a new way to study gallium oxide nanowires. Summary of the invention

[0006] The present invention aims to provide a method for preparing a self-assembled gallium oxide nanowire material by microwave plasma method.

[0007] Another object of the present invention is to provide a microwave plasma self-assembled gallium oxide nanowire material product prepared by the above method.

[0008] Another object of the present invention is to provide an application of the above product.

[0009] The object of the present invention is achieved by the following scheme: A method for preparing gallium oxide nanowire material by microwave plasma self-assembly, which uses microwave plasma under certain discharge power conditions to treat liquid gallium with microwave plasma, self-assembles and grows on a silicon wafer substrate, and prepares gallium oxide nanowire material, comprising the following steps: Silicon wafer processing: cut a 30*30mm silicon wafer as a reaction substrate and polish the surface of the silicon wafer; Place a small amount of metal gallium on top of the processed silicon wafer; then, Place the silicon wafer on the bracket of the microwave plasma reaction device, adjust the position and place it in the quartz tube of the reaction device; first keep the entire microwave plasma reaction device in vacuum, and then introduce a mixed gas consisting of water vapor and Ar gas; turn on the microwave plasma source, control the experimental temperature to 600℃, so that plasma is generated in the quartz tube, so that the metal gallium droplets and water plasma form a gallium plasma ball, and the gas pressure is maintained at 40 Torr under the condition of power 600 W. The experiment is stopped after 1~2 hours of reaction; The silicon wafer was taken out and the white powder was scraped off to obtain gallium oxide nanowires.

[0010] The invention gallium oxide nanowires are prepared in a microwave plasma generator, which consists of three parts: a plasma reaction device, a vacuum system, and a gas distribution system. The experimental raw materials are composed of a mixture of water vapor and argon (Ar), wherein the water vapor is obtained by heating an aqueous solution and Ar is a carrier gas; after the water vapor is excited by microwaves in the discharge chamber to form a water plasma, it reacts with gallium to generate gallium oxide and releases hydrogen, finally obtaining gallium oxide nanowire materials.

[0011] The vacuum degree of the gallium oxide nanowire material is maintained at 1.0 × 10 -2 Torr or less.

[0012] The experimental temperature is controlled at 600°C.

[0013] When a mixed gas consisting of water vapor and Ar gas is introduced, the flow rate is maintained at 100~200 sccm.

[0014] The present invention also provides a microwave plasma self-assembled gallium oxide nanowire material, which is prepared according to any of the above methods.

[0015] The present invention also provides an application of microwave plasma self-assembled gallium oxide nanowire material as a gas sensor material.

[0016] Activity test of β-gallium oxide nanowire gas sensing performance: Scrape the prepared gallium oxide nanowire white powder off the base silicon wafer, then weigh 0.5 mg and put it into 5 ml of anhydrous ethanol. After 20 minutes of ultrasonic dispersion, a stable suspension is formed. Use a double-sided polished silicon wafer as the substrate and drop a few drops of the suspension on the surface of the silicon wafer. Finally, the suspension is dried in air, and after the ethanol is completely evaporated, a bright white film is formed on the surface of the silicon wafer. After the film is prepared, silver paste is dripped on both sides as electrodes, and platinum wires are led out at both ends of the electrodes. In this way, the self-assembled β-gallium oxide nanowire thin film gas sensor is completed. The activity of the gas sensor is tested using a conductor parameter tester under different oxygen concentrations. The technical feature of the present invention is that a specific microwave plasma method is used to treat metal gallium. The metal Ga is in a liquid state and is exposed to water vapor microwave plasma to form a plasma-liquid contact surface, so that it can react with water ions to directly produce Ga2O3 nanowire materials, as shown in the reaction formula: 2Ga + 3H2O → Ga2O3+ 3H2.

[0017] The one-dimensional nanowire structure is mainly derived from the spontaneous generation of microwave plasma under radial conditions. The reaction between liquid Ga and plasma H2O leads to the generation of gallium oxide crystal nuclei. During microwave heating, energy acts on the entire heated body, and the inside and outside are heated at the same time, without relying on thermal diffusion, to achieve rapid overall heating. Due to the short time and no thermal hysteresis, gallium oxide shrinks to form nanowire materials. Microwave plasma heating has the characteristics of time saving, high efficiency, energy saving, and no pollution. This process does not add other auxiliary materials, so it is an ideal preparation method, which provides a new way to study gallium oxide nanowires. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a scanning electron microscope (SEM) image of the microwave plasma oxidized gallium nanowires obtained in Example 1.

[0019] It can be seen from the spectrum that the length of the gallium oxide nanowires is between 10 and 20 μm, and the diameter is between 400 and 800 nm. DETAILED DESCRIPTION

[0020] This embodiment is implemented on the premise of the technical solution of the present invention, and provides a detailed implementation method and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0021] Embodiment 1: A microwave plasma method self-assembled gallium oxide nanowire material, liquid gallium is subjected to microwave plasma treatment, self-assembled and grown on a silicon wafer substrate, and the gallium oxide nanowire material is prepared according to the following steps: Silicon wafer processing: cut a 30*30mm silicon wafer as a reaction substrate and polish the surface of the silicon wafer; Place 0.5g of metal gallium block on the processed silicon wafer; then, Place the silicon wafer on the bracket of the microwave plasma reaction device and adjust the position to put it into the quartz tube of the reaction device. During the experiment, first keep the vacuum system of the entire microwave plasma reaction device at 1.0 × 10 -2 Torr or less, then introduce a mixed gas consisting of water vapor and Ar gas, with the flow rate maintained at 100 sccm; turn on the microwave plasma source, control the experimental temperature at 600°C, generate plasma in the quartz tube, and make it form a plasma ball around the metal gallium droplet, keep the pressure at 40 Torr under the condition of power 600 W, and stop the experiment after 1 hour of reaction; The silicon wafer was taken out and the white powder was scraped off to obtain gallium oxide nanowires.

[0022] The scanning electron microscope (SEM) spectrum of the obtained gallium oxide nanowires is shown in Figure 1As shown, it can be seen from the spectrum that the length of the gallium oxide nanowires is in the range of 10~20μm and the diameter is in the range of 400~800nm.

[0023] Embodiment 2: A microwave plasma self-assembled gallium oxide nanowire material is prepared in the following steps similar to those in Example 1: Silicon wafer processing: cut a piece of silicon wafer with a size of 30*30mm as the reaction substrate and polish the surface of the silicon wafer; Place 0.5g of metal gallium block on the silicon wafer; then, The silicon wafer was placed on the support of the microwave plasma reaction device and adjusted to fit into the reaction quartz tube. During the experiment, the vacuum system of the entire reaction device was maintained at 2.0 × 10 -2 Torr, then introduce a mixed gas consisting of water vapor and Ar gas, with a flow rate of 150 sccm; turn on the microwave plasma generator, control the experimental temperature, generate plasma in the quartz tube, and make it form a plasma ball around the metal gallium droplet, keep the pressure at 40 Torr under the condition of power 600 W, and stop the experiment after 1 hour of reaction. Take out the reacted silicon wafer to obtain gallium oxide nanowires.

[0024] Embodiment 3: A microwave plasma self-assembled gallium oxide nanowire material is prepared in the following steps similar to those in Example 1: Silicon wafer processing: cut a piece of silicon wafer with a size of 30*30mm as the reaction substrate and polish the surface of the silicon wafer; Place 0.1g of metal gallium block on the silicon wafer; then, Place the silicon wafer on the bracket of the microwave plasma reaction device and adjust the position to place it in the quartz tube of the reaction. During the experiment, the vacuum system of the entire device was maintained at 3.0 × 10 -2 Torr, then introduce a mixed gas consisting of water vapor and Ar gas, with the flow rate maintained at 200 sccm; turn on the microwave plasma source, control the experimental temperature, generate plasma in the quartz tube, and make it form a plasma ball around the metal gallium droplet, keep the gas pressure at 40 Torr under the condition of power 600 W, and stop the experiment after 1 hour of reaction; The reacted silicon wafer is taken out to obtain gallium oxide nanowires.

[0025] The application of the prepared gallium oxide nanowires for gas sensor materials is implemented as follows: Activity test of β-gallium oxide nanowire gas sensing performance: The prepared white powder of gallium oxide nanowires was scraped off the base silicon wafer, and then 0.5 mg was weighed and put into 5 ml of anhydrous ethanol. After 20 minutes of ultrasonic dispersion, a stable suspension was formed. A double-sided polished silicon wafer was used as the substrate, and a few drops of the suspension were dripped on the surface of the silicon wafer. Finally, the suspension was dried in air, and after the ethanol was completely evaporated, a bright white film was formed on the surface of the silicon wafer. After the film was prepared, silver paste was dripped on both sides as electrodes, and platinum wires were led out at both ends of the electrodes. In this way, the self-assembled β-gallium oxide nanowire thin film gas sensor was completed.

[0026] The activity test of the gas sensor was carried out by a conductor parameter tester under different oxygen concentrations. The results are shown in Table 1. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a microwave plasma self-assembled gallium oxide nanowire material, characterized in that Liquid gallium is subjected to microwave plasma treatment to self-assemble and grow on a silicon wafer substrate to prepare gallium oxide nanowire material, including the following steps: Silicon wafer processing: cut a 30*30mm silicon wafer as a reaction substrate and polish the surface of the silicon wafer; Place a small amount of metal gallium on top of the processed silicon wafer; then, Place the silicon wafer on the bracket of the microwave plasma reaction device, adjust the position and place it in the quartz tube of the reaction device; first keep the entire microwave plasma reaction device in vacuum, and then introduce a mixed gas consisting of water vapor and Ar gas; turn on the microwave plasma source, control the experimental temperature to 600℃, so that plasma is generated in the quartz tube, so that the metal gallium droplets and water plasma form a gallium plasma ball, and the gas pressure is maintained at 40 Torr under the condition of power 600 W. The experiment is stopped after 1~2 hours of reaction; The silicon wafer was taken out and the white powder was scraped off to obtain gallium oxide nanowires.

2. The method for preparing gallium oxide nanowire material by microwave plasma self-assembly according to claim 1, characterized in that: The vacuum degree of the gallium oxide nanowire material is maintained at <1.0 × 10 -2 Torr.

3. The method for preparing gallium oxide nanowire material by microwave plasma self-assembly according to claim 1, characterized in that: When a mixed gas consisting of water vapor and Ar gas is introduced, the flow rate is maintained at 100~200 sccm.

4. The method for preparing gallium oxide nanowire material self-assembled by microwave plasma method according to any one of claims 1 to 3, characterized in that: Prepare as follows: Silicon wafer processing: cut a 30*30mm silicon wafer as a reaction substrate and polish the surface of the silicon wafer; Place 0.5g of metal gallium block on the processed silicon wafer; then, Place the silicon wafer on the bracket of the microwave plasma reaction device and adjust the position to put it into the quartz tube of the reaction device. During the experiment, first keep the vacuum system of the entire microwave plasma reaction device at 1.0 × 10 -2 Torr or less, then introduce a mixed gas consisting of water vapor and Ar gas, with the flow rate maintained at 100 sccm; turn on the microwave plasma source, control the experimental temperature at 600°C, generate plasma in the quartz tube, and make it form a plasma ball around the metal gallium droplet, keep the pressure at 40 Torr under the condition of power 600 W, and stop the experiment after 1 hour of reaction; The silicon wafer was taken out and the white powder was scraped off to obtain gallium oxide nanowires.

5. The method for preparing gallium oxide nanowire material self-assembled by microwave plasma method according to any one of claims 1 to 3, characterized in that: The preparation was carried out in the following steps: silicon wafer processing, a silicon wafer with a size of 30*30 mm was cut as a reaction substrate, and the surface of the silicon wafer was polished; Place 0.5g of metal gallium block on the silicon wafer; then, The silicon wafer was placed on the support of the microwave plasma reaction device and adjusted to fit into the reaction quartz tube. During the experiment, the vacuum system of the entire reaction device was maintained at 2.0 × 10 -2 Torr, then introduce a mixed gas consisting of water vapor and Ar gas, with the flow rate maintained at 150 sccm; turn on the microwave plasma generator, control the experimental temperature, generate plasma in the quartz tube, and make it form a plasma ball around the metal gallium droplet, keep the gas pressure at 40 Torr under the condition of power 600 W, and stop the experiment after 1 hour of reaction; The reacted silicon wafer is taken out to obtain gallium oxide nanowires.

6. The method for preparing gallium oxide nanowire material self-assembled by microwave plasma method according to any one of claims 1 to 3, characterized in that: The preparation was carried out in the following steps: silicon wafer processing, a silicon wafer with a size of 30*30 mm was cut as a reaction substrate, and the surface of the silicon wafer was polished; Place 0.1g of metal gallium block on the silicon wafer; then, Place the silicon wafer on the bracket of the microwave plasma reaction device and adjust the position to place it in the reaction quartz tube. During the experiment, the vacuum system of the entire device was maintained at 3.0 × 10 -2 Torr, then introduce a mixed gas consisting of water vapor and Ar gas, with the flow rate maintained at 200 sccm; turn on the microwave plasma source, control the experimental temperature, generate plasma in the quartz tube, and make it form a plasma ball around the metal gallium droplet, keep the gas pressure at 40 Torr under the condition of power 600 W, and stop the experiment after 1 hour of reaction; The reacted silicon wafer is taken out to obtain gallium oxide nanowires.

7. A microwave plasma self-assembled gallium oxide nanowire material, characterized in that Prepared according to any one of claims 1 to 4.

8. Use of the microwave plasma self-assembled gallium oxide nanowire material according to claim 7 as a gas sensor material.

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