Dependence of gas sensitivity on micro-structures of SnO₂ thin films deposited by RF-sputtering

Abstract

The influence of RF-sputtering conditions on the micro-structures of SnO₂ thin films were investigated and the mechanism of gas sensing in the film was studied. As a result, the micro-structure (morphologic and crystallografic) of SnO₂ thin films was well affected by sputtering gas pressures. In this case, the granular size of SnO₂ and distance between granules increased as the pressure was increased. Moreover, post-annealing for the films enhanced these tendencies. For the gas sensitivity, the more porous the film structure was, the higher the sensitivity was. On the other hand, the gas response time was just opposite to that. From these results, the sensitivity of SnO₂ thin films remarkably depends on the film porosity and gas diffusivity into the films.