Preparation Of SnO₂Thin Films By Sol-gel Method

Tin dioxide（SnO₂） with N-type semiconductor structure is an excellent gas-sensingmaterial. Tin dioxide film has many excellent properties such as electrical conductivity,transparency is relatively high and stable chemical properties.Tin oxide thin film sensorscan be used to detect environmental pollution, the sensors doped metal elements can also betransparent conductive film, widely used in the field of liquid crystal displays and opticaltechnology, microwave reflection. The performance of sensors depends primarily on the filmproperties, and the properties of the film is strictly dependent on the preparation method.Therefore, It is particularly important to select efficient and practical experimental process.Most research reported are methods by spraying, vapor deposition, electro evaporation,magnetron sputtering to the preparation of tin dioxide film. although these methods havethire own advantages, but they require expensive equipment. Sol-gel process is acommonly used method for preparing a polyhydric oxide film, it can control amount ofdoping, and its low temperature operation conditions is easy to implement, and it is able tolarge area uniform film.So its development has be very rapid recent years.Many past studies show that the change of the film preparation conditions or testconditions can affect the size of the SnO₂particle diameter, so that it is possible to improvegas sensitivity by controlling material properties. In this paper, inorganic stannous oxalate（SnC₂O₄） is used to prepare a precursor solution, adding a small amount of complexingagent, by the sol-gel to prepare tin dioxide sol. Preparing thin films on an aluminasubstrate with silver electrodes by spin coating method to control the film-formingconditions, the tin oxide thin film formation process of sintering temperature on thegas-sensing properties, and the impact of thin film gas sensitivity to external factors isdiscussed.The main researching contents include:（1） the research on process of the sol-gel methodSnO₂film, through the experiment to explore different preparation SnO₂thin film on the process conditions, such as film thickness, annealing temperature.（2） Analysis XRD andthickness test of SnO₂film.（3）To study the gas sensing properties of SnO₂films in different test temperature to H2S gas,derived by comparing the best performance in the film prepared and tested processconditions.（4） the four-probe tester is used to study resistors of tin oxide thin, thickness andheatint treatment temperature on the thin film are also studyed to pave the way for furtherresearch on thin-film conductive. In the paper, experimental results show that using thesol-gel method produced excellent performance of SnO₂thin film, the film sintered at550℃has a best sensitivity obtained at90℃measuring temperature.