Ozone sensing properties of polycrystalline indium oxide films at room temperature

The room temperature ozone sensing properties of polycrystalline indium oxi de (InOx) thin films have been investigated. Films with thicknesses of 10 t o 1100 nm were sputtered in a dc-magnetron system onto Coming 7059 glass at various substrate temperatures and sputtering atmospheres. Initially, as-g rown films were brought to a high conducting state through a photoreduction process by UV light exposure and subsequently they were exposed to a contr olled ozone atmosphere. By this treatment the sensitivity of the films coul d be monitored. The films exhibit resistivity changes of more than five ord ers of magnitude. The sensitivity was studied for different ozone concentra tions and at different temperatures. The response of the films increased li nearly with the ozone concentration and the highest sensitivity was achieve d when the measurements were carried out at room temperature. Best results were achieved with very thin InOx films (< 100 nm) deposited at room temper ature in a pure oxygen atmosphere.