Hall coefficient measurements for SnO2 doped sensors, as a function of temperature and atmosphere

Abstract

The Hall coefficient has been measured for thin (300 nm) r.f. sputtered Al, In-doped SnO2 and undoped SnO2 films. Two experiments have been carried out: (i) Hall measurements in a temperature range of 20 to 300 °C in inert (Ar), reductor (H2 0.2%) and oxidant (O2 2%) atmospheres. Aged films were also tested in Ar. (ii) Hall measurements as a function of H2 (0-2%) and O2 (0-20%) concentrations at fixed temperature. Conduction mechanisms were discussed adjusting temperature dependent results to a grain boundary carried-trapping model. A grain size dependent sensitivity model has been used to explain H2 and O2 sensitivities. Combining results from both models, we are able to establish the best conditions for detection of reductor and oxidant gases. © 1993.