Auger Analysis of Thermally Oxidized GaAs Surfaces

Abstract

We have investigated in‐depth composition profiles of the crystals with thermally oxidized (100) and (111) surfaces by Auger electron spectroscopy during Ar sputter etching. The Ga depletion is found at two different positions when the oxide thickness is less than about 250 and about 140Å for the closed‐ and the open‐tube oxidation, respectively. One of the positions is within the oxide layer and is always accompanied by the increase in As concentration, while the other is at the interface and appears upon the formation of thicker than ∼50Å. It is found that the oxide growth rate, the transition layer width, and the composition ratio between As and Ga near the interface strongly depend upon the surface orientation. It turns out that there are three different oxidation kinetics as functions of oxide thickness: the reaction of oxygen with at the interface, and in‐ and out‐diffusions of oxidizing species and Ga.