Influence of deuterium and platinum on the thermal oxidation of GaAs

The thermal oxidation of GaAs at 500 degreesC in O-18 labeled O-2 has been studied with gas phase analysis, Auger electron spectroscopy, secondary ion mass spectrometry, and X-ray photoelectron spectroscopy. The influence of a few hundred atomic parts per million of deuterium in the GaAs substrate and of surface platinum have been evaluated with respect to oxide growth mechanisms and the degree of As buildup. Deuterium increased the transport from the substrate interface of both Ga and As toward the gas interface thereby lowering the degree of preferential Ga oxidation and As buildup at the substrate interface. Platinum, on the other hand, catalyzed the dissociation of the oxygen molecule at the gas interface and thereby facilitated an increased transport of oxygen toward the substrate interface. That results in an increased overall oxidation rate with a high degree of preferential Ga oxidation and concomitant As buildup. When the oxygen pressure was increased from 20 to 720 mbar, a lowered degree of As buildup was observed due to the lower degree of preferential Ga oxidation. (C) 2003 The Electrochemical Society.