Lateral oxidation of AlAs thin films

Abstract

Transmission electron microscopy was used for characterization of microstructure resulting from wet oxidation of AlAs layers of different thicknesses separated by a 20 nm thick GaAs layer. In general, the oxidation rate was related to the AlAs layer thickness, but some deviation from this rule was observed for layer thicknesses in the range of 65 to 30 nm. Accumulation of As precipitates at the AlAs/GaAs/AlAs interfaces and in the GaAs separation layers was observed. A build up of stress at these interfaces occasionally caused formation of stacking faults close to the oxidation front. Large differences in interface abruptness were observed for direct (AlAs on GaAs) and inverted (GaAs on AlAs) interfaces. The oxidation front was asymmetric with the faster front close to the inverted interface.