Improvement of the interface quality during thermal oxidation of Al0.98Ga0.02As layers due to the presence of low-temperature-grown GaAs

The role of a low-temperature-grown GaAs (LT GaAs) layer on the lateral oxi dation of an Al0.98Ga0.02As/GaAs layer structure has been studied by transm ission electron microscopy. Results show that structures incorporating LT G aAs develop better quality oxide/GaAs interfaces compared to reference samp les without LT GaAs. While the latter have As accumulation in the vicinity of these interfaces, the structures with LT layers display sharper oxide-Ga As interfaces with a reduced concentration of As. These results are explain ed in terms of the high Ga vacancy concentration in the LT GaAs and the pos sible influence of those vacancies in enhancing As diffusion away from the oxide-semiconductor interface. (C) 2000 American Institute of Physics. [S00 03-6951(00)01328-0].