Morphology and inner structure of ethanol sensitive thin films of tin oxide operating at near room temperature

Thin tin oxide films were fabricated by reactive RF magnetron sputtering. It was shown that the films possess gas sensitivity to ethanol vapor at 38$^\circ$C. Measurements of the morphology and cleavage inner structure of the samples by atomic-force and scanning electron microscopy demonstrate that the films are composed of nanodimensional rod-like grains oriented normally to the substrate. The grains are separated by pores piercing the whole film. It was found that the grain diameter distribution is normal logarithmic one with several centers related as small integers, which indicates that the grains coalesce. The minimum grain size of 6 nm might correspond to the critical nucleus size under the used conditions of film deposition.