Microstructure and gas-sensing properties of(Sn,Ti)O-2 thin films deposited by RGTO technique

The application of the RGTO (rheotaxial growth and thermal oxidation) techn ique to the deposition of(Sn,Ti)O-2 thin films is described. Phase composit ion, microstructure, surface roughness and gas-sensing properties of thin f ilms were studied. The comparison between the films grown by RGTO and those obtained in the reactive rf sputtering is given. The structure modelling h as been performed to account for the presence of two crystallographic phase s: tetragonal; and orthorhombic in the RGTO-thin films. It is shown that RG TO yields oxides of extremely rough surfaces. Illumination of such a layer with an electromagnetic wave of the wavelength comparable with dimensions o f surface irregularities results in an enhanced light scattering. The elect rical responses to 200-10000 ppm H-2 and 150-1000 ppm CH4 are reproducible and significant at the sensor operating temperature of 400 degreesC. (C) 20 01 Elsevier Science B.V. All rights reserved.