H-2-INDUCED SURFACE AND INTERFACE POTENTIALS ON PD-ACTIVATED SNO2 SENSOR FILMS

The surface and interface potentials of an SnO2 gas-sensor film have been investigated by a vibrating capacitor probe, resistivity measurements, the MOS Q-V method and thermoelectric power measurements. All results are converted into potential changes, and plotted as a function of the H-2 partial pressure in the ambient air. The maximum value of the potential change on the surface is about 0.5-0.6 V. Potential changes calculated from the resistivity measurements are smaller, as well as the potential changes at the SnO2-substrate interface. Based on the results, a simple energy-band model and the charge-carrier concentrations are discussed.