Effects of substrate temperature on structural properties of tin oxide films produced by plasma oxidation after thermal evaporation

Abstract

In this study, tin film was thermally evaporated onto a stainless steel substrate in an argon atmosphere. The tin films were then subjected to a DC plasma oxidation process using an oxygen/argon gas mixture. Three different substrate temperatures (100 °C, 150 °C, and 200 °C) and three different oxygen partial pressures (12.5%, 25%, and 50%) were used to investigate the physical and microstructural properties of the films. The surface properties were studied by scanning electron microscopy, X-ray diffraction, atomic force microscopy and a four-point probe electrical resistivity measurement. The grain size and texture coeffcient of the tin oxide films were calculated. Both SnO and SnO2 films with grain sizes of 13-43 nm were produced, depending on the oxygen partial pressure. SnO films have flower-andake-like nanostructures, and SnO2 films have grape-like structures with nanograins. The resistivity values for the SnO2 phase were found to be as low as 105 cm and were observed to decrease with increasing substrate temperature.