Preparation Of Tin Oxide Thin Films By Thermal Evaporation

Tin oxide(SnO2) is a transparent and wide-band gap(Eg=3.6eV at room temperature)semiconductor, with good transparency in the visible region, high absorption coefficient to ultraviolet radiation, excellent electrical conductivity, and high chemical sensitivity. These films have been exploited as high-frequency electronic devices, transparent electrode of solar cells and displays, gas-sensors and so on.Tin oxide thin films have been prepared by many methods, such as magnetron sputtering, RF-sputtering, metalorganic decomposition, ultrasonic spray pyrolysis, thermal evaporation, pulsed laser deposition, CVD, sol-gel and so on. Among these methods, the thermal evaporation is of great importance technologically because of its simplicity in equipment, facility in process and low-cost. This work attempts to exploit the growth process of SnO2 films and provide reference for future industrial application.In this paper, tin oxide films have been synthesized by thermal evaporation on the basis of related theories. Tin oxide films were prepared under different deposition conditions. The effects of process parameters such as temperature and ambient atmosphere on the film growth were investigated. The obtained films were characterized by XRD, SEM, and Raman spectroscopy. The luminescence properties were also measured by cathodoluminescence.It is indicated that the optimal deposition temperature is dependent on the substrate materials and the position put the substrate. Purer tin oxide films were obtained at 900℃on CNTs substrates, and were obtained at around 1380℃on Si substrate.The prepared tin film is polycrystalline and not uniform in crystallinity. Some holes can be observed on the films. CL measurement shows that luminescence spectra are different dependant on the deposition conditions.