Structural and functional properties of SnO/sub 2/ sol-gel derived thin films for integrated gas sensors

We present the structural and gas sensing properties of the sol-gel derived SnO/sub 2/ thin films exposed to small concentrations of reducing and oxidant ambient. XRD investigations show the structural evolution of the film as a function of sol-gel processing parameters. Nanometric grain size relation to metal atom doping has been obtained. For the functional characterisation of our SnO/sub 2/ sensing films, we propose an integrated technology for a simple test microstructure, based on resistive heater made of boron doped silicon and W/Au metallization for both sensor electrodes and heater contact. AFM investigations of SnO/sub 2/ thin films revealed the morphology of the films used for gas sensing applications. A test structure having medium electrical power consumption (below 900 mW) was used for the detection of the controlled concentrations of CH/sub 4/, CH/sub 3/COOH, and NO/sub 2/ at low temperatures.