Method of preparing zinc oxide/titanium dioxide composite self-assembly thin film gas sensitive device

Abstract

The invention provides a method for preparing zinc oxide / titanic oxide composite self-assembled thin film air-sensitive device, which includes the following steps: first performing a special treatment of the substrate, and then the substrate has electric charges, then dipping the substrate into a ZnO2 sol with positive electrical charges, TiO2 sol with positive electrical charges and polyelectrolyte solution with negative charges in [(ZnO / PSS) / (TiO2 / PSS)]n sequence respectively, cleaning the substrate with deionized water after the substrate is fetched from the solution or sol every time, drying the substrate with argon gas or nitrogen. Under the action of the electrostatic gravitational force, the ZnO2 sol grain, the TiO2 sol grain and the polyelectrolyte are adsorbed on the surface of the substrate layer by layer, the process is repeated seriously, the ZnO2 / TiO2 composite self-assembled air-sensitive thin films with various thicknesses are made. Then, a ZnO / TiO2 composite self-assembled grain air-sensitive thin film is obtained by heat treating. The method has simple technique, the substrate shape has no special requirements, and the thickness of the film is controlled in the molecule level, the film-forming has good repeatability. The obtained ZnO / TiO2 composite self-assembled grain air-sensitive thin film can be used for the preparation of the gas-sensitive sensor device.

Description

(1) Technical field [0001] The invention provides a zinc oxide / titanium dioxide (ZnO / TiO 2 ) A method for preparing a composite self-assembled thin film gas sensor, which relates to a method for preparing a metal oxide semiconductor thin film gas sensor by using layer-by-layer electrostatic self-assembly, especially involving the preparation of ZnO / TiO by layer-by-layer electrostatic self-assembly 2 The invention relates to a method for a composite film gas sensor, belonging to the technical field of material science. (2) Background technology [0002] Although due to surface effects and other reasons, the gas sensor with single-layer thin film structure has obvious advantages in performance compared with sintered and thick film gas sensors. But there are still some weaknesses, especially the poor selectivity to some gases, and although the material stability has been improved, it is still not ideal. For the multi-layer thin film structure, each layer of thin film will dif...

AI Technical Summary

Problems solved by technology

[0003] Zinc oxide (ZnO) is the earliest semiconductor gas-sensing material, which is a surface-controlled gas-sensing material. Its physical and chemical properties are stable, and it can be used as a gas-sensing sensor material to detect a variety of gases, but it also has high operating temperature, Due to the shortcomings of long response time and low sensitivity, in order to improve the gas sensing performance of ZnO, some precious metals are often added as catalysts.

Precious metals such as silver (Ag), platinum (Pt), palladium (Pd) can significantly improve the gas sensing performance of ZnO, but their cost is high, and the sensitivity and life of the element will be reduced due to poisoning. Cheap metal oxides are used as doping If the agent is used, there will be no poisoning phenomenon, and it can improve the stability and sensitivity of the element, especially have a significant effect on the gas selectivity of the element

Titanium dioxide (TiO 2 ) itself has no obvious gas-sensing effect, but when mixed with other gas-sensing materials, it often has a more obvious performance improvement

Images