阅读说明：本技术 一种半导体薄膜气体传感器及其制备方法 (Semiconductor film gas sensor and preparation method thereof ) 是由 黄辉 渠波 尚瑞晨 赵丹娜 王梦圆 李志瑞 蔡伟成 于 2020-06-01 设计创作，主要内容包括：本发明涉及一种半导体薄膜气体传感器及其制备方法。该半导体薄膜气体传感器包括衬底、以及设置于所述衬底第一表面的半导体薄膜；所述半导体薄膜表面设置有电极；所述半导体薄膜的上方设置有用于照射所述半导体薄膜的光源；或,所述半导体薄膜底部设置有用于照射所述半导体薄膜的光源；或,所述衬底的第二表面设置有用于照射所述半导体薄膜的光源,所述衬底第一表面和所述衬底第二表面相对设置。本发明通过设置光源照射半导体薄膜,可以提高灵敏度,从而避免了高温加热,功耗更低、更为稳定,其可以检测氧气和甲烷,而现有SnO<Sub>2</Sub>纳米颗粒传感器对空气氛围中的氧气灵敏度很差。(The invention relates to a semiconductor film gas sensor and a preparation method thereof. The semiconductor film gas sensor comprises a substrate and a semiconductor film arranged on a first surface of the substrate; an electrode is arranged on the surface of the semiconductor film; a light source for irradiating the semiconductor film is arranged above the semiconductor film; or a light source for irradiating the semiconductor film is arranged at the bottom of the semiconductor film; or the second surface of the substrate is provided with a light source for irradiating the semiconductor thin film, and the first surface of the substrate and the second surface of the substrate are oppositely arranged. The invention can improve the sensitivity by arranging the light source to irradiate the semiconductor film, thereby avoiding high-temperature heating, having lower power consumption and more stability, and being capable of detecting oxygen and methane, compared with the prior SnO 2 Nanoparticle sensors have poor sensitivity to oxygen in the air atmosphere.)

1. A semiconductor thin film gas sensor, characterized by: the semiconductor thin film gas sensor comprises a substrate and a semiconductor thin film arranged on a first surface of the substrate;

an electrode is arranged on the surface of the semiconductor film;

a light source for irradiating the semiconductor film is arranged above the semiconductor film; or the like, or, alternatively,

a light source for irradiating the semiconductor film is arranged at the bottom of the semiconductor film; or the like, or, alternatively,

the second surface of the substrate is provided with a light source for irradiating the semiconductor thin film, and the first surface of the substrate and the second surface of the substrate are oppositely arranged.

2. The semiconductor thin film gas sensor according to claim 1, wherein the semiconductor thin film is made of a semiconductor oxide material or a composite material of semiconductor oxides.

3. The semiconductor thin film gas sensor according to claim 2, wherein the semiconductor oxide comprises zinc oxide, tin oxide, indium oxide, gallium oxide, nickel oxide, titanium oxide, tungsten oxide, or copper oxide.

4. The semiconductor thin film gas sensor according to any one of claims 1 to 3, wherein the semiconductor thin film is made of a material sensitive to oxygen, methane, or a volatile organic compound.

5. The semiconductor thin film gas sensor according to any one of claims 1 to 3, wherein a surface of the semiconductor thin film is plated with a catalyst.

6. The semiconductor thin film gas sensor according to any one of claims 1 to 3, wherein the electrodes are provided at both end positions of the surface of the semiconductor thin film.

7. The semiconductor thin film gas sensor according to any one of claims 1 to 3, wherein the substrate is a silicon substrate, a quartz substrate, or a sapphire substrate, and the light source is an LED.

8. The semiconductor thin film gas sensor according to claim 7, wherein the light source has a wavelength of less than 450nm and a power of less than 20 mW.

9. A method of making a semiconductor thin film gas sensor, the method comprising:

(1) depositing a semiconductor oxide film on the first surface of the substrate; or the like, or, alternatively,

depositing a metal film on the first surface of the substrate, and then placing the substrate in an oxygen atmosphere for high-temperature heating so that the metal film is oxidized into a semiconductor oxide film.

(2) Preparing two electrodes on the surface of the semiconductor film;

(3) arranging a light source above the semiconductor film to irradiate the semiconductor film; or the like, or, alternatively,

arranging a light source at the bottom of the semiconductor film to irradiate the semiconductor film; or the like, or, alternatively,

and arranging a light source on the second surface of the substrate to irradiate the semiconductor film, wherein the first surface of the substrate and the second surface of the substrate are oppositely arranged.

10. The production method according to claim 9, wherein in step (3), the semiconductor oxide thin film is heated at a low temperature.

Technical Field

The invention relates to the technical field of semiconductor sensors, in particular to a semiconductor film gas sensor and a preparation method thereof.

Background

Semiconductor thin film gas sensors are widely used to detect the components (i.e., trace species content) of a liquid or gas sample, and the operating principle thereof is as follows: an analyte (such as ions or molecules) contacts with the surface of the semiconductor and chemically reacts on the surface, thereby changing the resistance (or generating a reaction current) of the semiconductor material (Nano Today,2011,6, 131-.

In order to improve the detection sensitivity of the sensor, the specific surface area of the sensitive material needs to be increased, for example, nanoparticles are used as the sensitive material. Currently, most of semiconductor gas sensor products adopt SnO₂The nano-particles are used as sensitive materials,this sensitive material has the following disadvantages: the nano particles are easily influenced by external temperature and humidity, and have poor stability; requires high-temperature heating>200 ℃, hereinafter referred to as "degree") and large power consumption; at high temperature, the grain boundary defects of the nanoparticles move, the crystal grains become large, and the sensitivity deteriorates; is insensitive to oxygen in air atmosphere. Compared with nanoparticles, the stability of the thin film material can be greatly improved, but the sensitivity is lower.

At present, by adopting illumination instead of high-temperature heating, the power consumption of the sensor can be reduced. However, the existing nanoparticle sensitive material has a complex preparation process and poor consistency. For thin film sensitive materials (such as oxide thin films), the oxide thin films are usually formed by direct deposition, the oxygen content of the thin films cannot be effectively controlled, and the crystal quality is poor (due to the low mobility of oxide molecules during deposition).

In summary, how to realize a semiconductor gas sensor with low power consumption and high stability is the initiative of the present invention.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a semiconductor thin film gas sensor and a preparation method thereof.

The invention discloses a semiconductor film gas sensor, which adopts the technical scheme that:

the semiconductor thin film gas sensor comprises a substrate and a semiconductor thin film arranged on the first surface of the substrate;

two electrodes are arranged on the surface of the semiconductor film;

a light source for irradiating the semiconductor film is arranged above the semiconductor film; or the like, or, alternatively,

a light source for irradiating the semiconductor film is arranged at the bottom of the semiconductor film; or the like, or, alternatively,

the second surface of the substrate is provided with a light source for irradiating the semiconductor thin film, and the first surface of the substrate and the second surface of the substrate are oppositely arranged.

The invention provides a semiconductor film gas sensor, which also comprises the following subsidiary technical scheme:

the semiconductor thin film is made of a semiconductor oxide material or a semiconductor oxide composite material.

Wherein the semiconductor oxide comprises zinc oxide, tin oxide, indium oxide, gallium oxide, nickel oxide, titanium oxide, tungsten oxide, or copper oxide.

Wherein the semiconductor film is made of a material sensitive to oxygen, methane or volatile organic compounds.

Wherein, the surface of the semiconductor film is plated with a catalyst.

The two electrodes are respectively arranged at two ends of the surface of the semiconductor film.

The substrate is a silicon substrate, a quartz substrate or a sapphire substrate, and the light source is an LED.

Wherein the wavelength of the light source is less than 450nm, and the power of the light source is less than 20 mW.

The invention also provides a preparation method of the semiconductor film gas sensor, which comprises the following steps:

(1) depositing a semiconductor oxide film on the first surface of the substrate; or the like, or, alternatively,

depositing a metal film on the first surface of the substrate, and then placing the substrate in an oxygen atmosphere for high-temperature heating so that the metal film is oxidized into a semiconductor oxide film.

(2) Preparing two electrodes on the surface of the semiconductor film;

(3) arranging a light source above the semiconductor film to irradiate the semiconductor film; or the like, or, alternatively,

arranging a light source at the bottom of the semiconductor film to irradiate the semiconductor film; or the like, or, alternatively,

and arranging a light source on the second surface of the substrate to irradiate the semiconductor film, wherein the first surface of the substrate and the second surface of the substrate are oppositely arranged.

Wherein, in the step (3), the semiconductor oxide film can be heated at a low temperature to remove the water vapor adsorbed on the surface of the film.

The invention provides a semiconductor film gasThe body sensor can improve the sensitivity by arranging the light source to irradiate the semiconductor film, thereby avoiding high-temperature heating, and having lower power consumption and more stability; the light absorption effect and the gas adsorption effect can be respectively optimized through the combination of different films; also, the semiconductor thin film gas sensor of the present invention can detect oxygen and methane, which is the conventional SnO₂Nanoparticle sensors have poor sensitivity to oxygen in air atmosphere.

Drawings

Fig. 1 is a schematic structural view of a semiconductor thin film gas sensor in example 1 of the present invention.

Fig. 2 is a schematic structural view of the semiconductor thin film gas sensor in embodiments 2 and 3 of the present invention.

Fig. 3 is a schematic structural view of a semiconductor thin film gas sensor in embodiment 4 of the present invention.

Detailed Description

The present invention will be described in detail with reference to examples.

The semiconductor thin film gas sensor provided in the present embodiment, as shown in fig. 1 to 3, includes a substrate 1, and a semiconductor thin film 2 disposed on a first surface of the substrate;

two electrodes 3 are arranged on the surface of the semiconductor film 2;

a light source 4 for irradiating the semiconductor thin film 2 is arranged above the semiconductor thin film 2; or, a light source 4 for irradiating the semiconductor thin film 2 is arranged at the bottom of the semiconductor thin film 2; or the like, or, alternatively,

the second surface of the substrate 1 is provided with a light source 4 for irradiating the semiconductor thin film 2, and the first surface of the substrate 1 and the second surface of the substrate are oppositely arranged.

The semiconductor thin film in this embodiment is grown on the substrate by using a chemical vapor deposition (e.g., CVD), a physical vapor deposition (e.g., magnetron sputtering), hydrothermal growth, or electrochemical growth.

When an analyte (ion, atom, or molecule) is adsorbed on the surface of the semiconductor thin film in this embodiment, the resistance of the thin film changes due to electron transfer (electron transfer between the thin film and the analyte) (the rate of change in resistance is referred to as sensitivity).

Preferably, the thickness of the semiconductor thin film 2 in the present embodiment is between 1nm and 1 μm.

According to the semiconductor film gas sensor provided by the invention, the sensitivity can be improved by arranging the light source to irradiate the semiconductor film, so that high-temperature heating is avoided, and the power consumption is lower and more stable; the light absorption effect and the gas adsorption effect can be respectively optimized through the combination of different films; also, the semiconductor thin film gas sensor of the present invention can detect oxygen and methane, which is the conventional SnO₂Nanoparticle sensors have poor sensitivity to oxygen in air atmosphere.

In one embodiment, the semiconductor thin film is made of a semiconductor oxide material or a composite material of semiconductor oxides.

In one embodiment, the semiconductor oxide includes zinc oxide, tin oxide, indium oxide, gallium oxide, or indium oxide.

Preferably, the semiconductor thin film is made of a composite material of tin oxide and indium oxide.

In this embodiment, the bottom film is used to absorb incident light, and the surface film is used to adsorb gas molecules, so that the semiconductor film in this embodiment can respectively optimize the illumination effect and the gas-sensitive property. Specifically, the bottom layer film absorbs photons, and generated photogenerated carriers (i.e., photogenerated electrons and photogenerated holes) can be diffused to the surface layer film, and the gas-sensitive property of the surface layer film is improved. For example, the diffusion of photo-generated electrons to the surface of the thin film helps chemisorb oxidizing gases (such as oxygen and nitrogen dioxide, etc.), thereby improving the sensitivity to the oxidizing gases; also, the photogenerated holes diffuse to the surface of the thin film, helping to chemisorb reducing gases (such as hydrogen and carbon monoxide, etc.), thereby improving the sensitivity to the reducing gases.

In one embodiment, the semiconductor thin film is made of a material sensitive to oxygen, methane, or volatile organic compounds.

In the present embodiment, the semiconductor thin film has high sensitivity to oxygen, methane, and VOC gases particularly at low temperatures (heating temperature less than 200 ℃). The VOC gas contains organic volatile gases such as formaldehyde, ethanol, benzene and the like.

In one embodiment, the surface of the semiconductor thin film is plated with a catalyst.

In this embodiment, the catalyst may be made of palladium or platinum, which may improve the sensitivity to a specific gas.

Illustratively, a palladium film is plated on the surface of the semiconductor film to improve sensitivity to hydrogen and carbon monoxide.

In one embodiment, the two electrodes are respectively disposed on the semiconductor film near two ends thereof.

In one embodiment, the substrate is a quartz substrate or a sapphire substrate and the light source is an LED.

In the embodiment, the LED also generates heat when emitting light, and the heat helps to remove the adsorbed water vapor on the surface of the semiconductor oxide film, thereby improving the gas-sensitive property and reducing the humidity effect.

In one embodiment, the light source has a wavelength of less than 450nm and the power of the light source is less than 20 mW.

The invention also provides a preparation method of the semiconductor film gas sensor, which comprises the following steps:

(1) growing a semiconductor oxide film on the first surface of the substrate;

(2) preparing two electrodes on the surface of the semiconductor film;

(3) arranging a light source above the semiconductor film to irradiate the semiconductor film; or the like, or, alternatively,

arranging a light source at the bottom of the semiconductor film to irradiate the semiconductor film; or the like, or, alternatively,

and arranging a light source on the second surface of the substrate to irradiate the semiconductor film, wherein the first surface of the substrate and the second surface of the substrate are oppositely arranged.

It should be noted that, in this embodiment, the semiconductor oxide film may be heated at a low temperature or without heating while being illuminated, so as to avoid the problem of large power consumption of the sensor caused by the conventional high-temperature heating.

The invention also provides a preparation method of the semiconductor film gas sensor, which comprises the following steps:

(1) and depositing a metal film on the first surface of the substrate, and then placing the substrate in an oxygen atmosphere for high-temperature heating to oxidize the metal film into a semiconductor oxide film.

(2) Preparing two electrodes on the surface of the semiconductor film;

(3) arranging a light source above the semiconductor film to irradiate the semiconductor film; or the like, or, alternatively,

arranging a light source at the bottom of the semiconductor film to irradiate the semiconductor film; or the like, or, alternatively,

and arranging a light source on the second surface of the substrate to irradiate the semiconductor film, wherein the first surface of the substrate and the second surface of the substrate are oppositely arranged.

In this embodiment, a metal film is deposited on the first surface of the substrate, and then the metal film is oxidized to form an oxide film. The process has the following advantages: because the mobility of metal atoms is higher, a compact crystal structure is easy to form; the oxide film formed by the subsequent high-temperature oxidation process can control the oxygen content in the film, wherein the oxygen content refers to oxygen components, and the oxide film has better crystal quality, namely is more compact and stable, so that the stability of the sensor is better.

In this embodiment, after the metal thin film is heated at a high temperature to form the bulk oxide thin film, the oxide thin film can be irradiated with light and heated at a low temperature, or heated without heating, so as to avoid the problem of high power consumption of the sensor caused by conventional high-temperature heating.

The semiconductor oxide film can control the oxygen component in the film, namely the oxidation degree, through high-temperature annealing, thereby improving the sensitivity to gas. Among other things, the oxygen content affects the resistivity and surface activity of the film, i.e., the ability of the surface to gain and lose electrons. For example, oxygen vacancies in the film can increase conductivity and surface activity.

The method for producing the semiconductor thin film gas sensor of the present invention will be described in detail below with specific examples.