Effects of thermal oxidation temperature on vacuum evaporated tin dioxide film

In order to investigate the effect of thermal oxidation temperature on tin dioxide (SnO2), tin dioxide films were obtained on quartz substrates by vacuum evaporation of tin metal. The films were characterized by X-ray diffraction (XRD) analyses, scanning electron microscopy (SEM), temperature dependent electrical resistivity measurement and optical absorption spectroscopy. The SEM images showed that the films are dense, continuous and are composed of nanoparticles and particle sizes are increased after thermal oxidation. From the X-ray measurement results, the films indicated two strong reflection peaks of tetragonal structure in the orientations of (1 0 1) and (2 0 0) at 2θ = 33.89° and 37.95°, respectively. Intensity of the peaks increased with increasing thermal oxidation temperature. We found resistivity values of about 10−4 Ω-cm. Optical absorption spectra of the films in the UV–Vis spectral range revealed that optical band gap (Eg) value of the films increases with increasing thermal oxidation temperature.

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► The films indicate two strong reflection peaks of tetragonal structure.
► Peaks belong to SnO2 were started to appear at 600 °C and increase at higher temperatures.
► Substrates were fully covered with nano-sized particles.
► Eg values of the films increase with increasing heat treatment temperature.