Time-dependent structural modifications in tin oxide thin films under environmental conditions

Abstract

Time-dependent crystalline structure and surface morphology of transparent conducting thin films of undoped tin oxide have been studied under environmental conditions by X-ray diffractometry and scanning electron microscopy. Tin oxide thin films were produced, via chemical vapour deposition, in three batches; two batches with single deposition at substrate temperatures of 400 ‡C and 560 ‡C, respectively, and the third batch produced by double deposition firstly at 560 ‡C and then at 400 ‡C substrate temperature. It is found that the crystallinity of the as-grown tin oxide thin films produced by single deposition degrades with shelf-life period and an amorphous phase is developed under environmental conditions. In the tin oxide films produced by double deposition there was no degradation in the crystallinity of the films, but a change in the preferential crystallite orientation was observed. The implications are discussed.