Spin-coated indium oxide thin film on alumina and silicon substrates and their gas sensing properties

Thin films of indium oxide were prepared on alumina and silicon substrates by spin-coating from an aqueous acetic acid solution dissolving In(OH)3 and ammonium carboxymethyl cellulose. The films could cover well the large grains of rough alumina as well as the flat surface of silicon. By changing the number of spin-coating, the film thickness was well controlled between 70nm and 210nm on alumina or between 65 nm and 220 nm on silicon, as observed by cross-sectional FE-SEM. Gas sensing properties including sensitivity, selectivity and the rates of response and recovery were strongly dependent on the kind of substrate, film thickness and operating temperature.