AUGER AND SIMS STUDY OF SEGREGATION AND CORROSION BEHAVIOR OF SOME SEMICONDUCTING OXIDE GAS-SENSOR MATERIALS

The influence of corrosive gases (H-2, CO, NO, Cl2, SO2) on the compos ition of sputtered polycrystalline SrTiO3, CeO2 and Ga2O3 thin films w as studied. Auger electron spectroscopy (AES) and secondary ion mass s pectroscopy (SIMS) were applied for studying the depth profiles of ato mic composition of the thin films, treated for several hundred hours a t 800-degrees-C in diluted (20 ppm, 5%) corrosive gases. SrTiO3 was st rongly attacked by Cl2 and SO2, During the Cl2 treatment the layer thi ckness was reduced and the structure altered near the grain boundaries . SO2 treatment caused a new surface phase formation (probably SrO). T he Ga2O3 layer had a fast reaction with Cl2 giving rise to volatile Ga products but the other corrosive gases had no deteriorating effect on the layer. CeO2 proved to be the most resistant to all the gases ment ioned above.