Phase composition of gas sensitive thin films of tin oxide operating at near room temperature

We have studied the phase composition of thin polycrystalline tin oxide films deposited on silicon substrates by reactive RF magnetron sputtering. The films are sensitive to ethanol vapors at 38$^\circ$C. They consist of SnO$_2$ crystallites with the average grain size of about 7 nm, covered with a nanodimensional layer of amorphous SnO phase. It was found that the volume fraction of the former phase is about 95% and that of the latter phase is about 5%. Calculations of the film texture indicate the predominant growth of SnO$_2$ crystals along $\langle$110$\rangle$, $\langle$211$\rangle$, and $\langle$310$\rangle$ crystal directions perpendicular to the substrate.