TIME-DEPENDENT STRUCTURAL MODIFICATIONS IN TIN OXIDE THIN-FILMS UNDERENVIRONMENTAL-CONDITIONS

Time-dependent crystalline structure and surface morphology of transpa rent conducting. thin films of undoped tin oxide have been studied und er environmental conditions by X-ray diffractometry and scanning elect ron microscopy. Tin oxide thin films were produced, via chemical vapou r deposition, in three batches; two batches with single deposition at substrate temperatures of 400 degrees C and 560 degrees C, respectivel y, and the third batch produced by double deposition firstly at 560 de grees C and then at 400 degrees C substrate temperature. It is found t hat the crystallinity of the as-grown tin oxide thin films produced by single deposition degrades with shelf-life period and an amorphous ph ase is developed under environmental conditions. In the tin oxide film s produced by double deposition there was no degradation in the crysta llinity of the films, but a change in the preferential crystallite ori entation was observed. The implications are discussed.