Enhancement of sensitivity and conductivity of semiconducting Ga2O3 gas sensors by doping with SnO2

The use of high temperature operated metal oxides, e.g. Ga2O3 thin films, for gas sensors shows promising properties in terms of reproducibility, long term stability against interfering gases and low cross sensitivity to humidity. It is shown that by employing SnO2 (0.1-3%(At)) as doping material, a very effective donor for sputter deposited polycrystalline Ga2O3 thin films has been found which allows an increase in conductivity of up to two orders of magnitude, as well as an enhancement of the gas-sensitivity. This is the basis for a significant reduction of the sensor chip size to obtain a reduction in the heating power. (C) 1998 Elsevier Science S.A. All rights reserved.