Microstructure and gas-sensing properties of (Sn,Ti)O2 thin films deposited by RGTO technique

Abstract The application of the RGTO (rheotaxial growth and thermal oxidation) technique to the deposition of (Sn,Ti)O 2 thin films is described. Phase composition, microstructure, surface roughness and gas-sensing properties of thin films were studied. The comparison between the films grown by RGTO and those obtained in the reactive rf sputtering is given. The structure modelling has been performed to account for the presence of two crystallographic phases: tetragonal; and orthorhombic in the RGTO-thin films. It is shown that RGTO yields oxides of extremely rough surfaces. Illumination of such a layer with an electromagnetic wave of the wavelength comparable with dimensions of surface irregularities results in an enhanced light scattering. The electrical responses to 200–10000 ppm H 2 and 150–1000 ppm CH 4 are reproducible and significant at the sensor operating temperature of 400°C.