EFFECTS OF LOW-TEMPERATURE ANNEALING ON THE NATIVE-OXIDE OF ALXGA1-XAS

Data are presented on the effects of low-temperature (approximately 540-degrees-C) annealing, with and without an As overpressure, on the native oxide of AlxGa1-xAs formed via water vapor oxidation at elevated temperature (approximately 425-degrees-C). Auger electron spectroscopy data show the Al to be oxidized while the Ga remains unoxidized after the water vapor oxidation of AlxGa1-xAs. Transmission electron microscopy data show a possible composition or phase change upon annealing with an As overpressure. Electron diffraction data indicate that the as-oxidized AlxGa1-xAs is a combination of four possible phases of Al2O3, eta, gamma, delta, chi, or AlO(OH). Supporting secondary-ion mass spectrometry data are also presented. Ellipsometer measurements indicate an index of refraction n=1.63 (lambda=6328 angstrom) for the native oxide. Ellipsometer measurements of the oxidized and annealed samples show the creation of a region 300-550 angstrom thick at the oxide-semiconductor interface with n=2.78-2.93.