Investigation of Microstructures of AlAs Oxides Before and After Oxidation

The effect of lateral oxidation on microstructures of the GaAs/AlAs/GaAs heterostructure was studied by x-ray specular reflectivity, nonspecular scattering and diffraction. The GaAs/Al₂O₃/GaAs multilayer was obtained after oxidation of the GaAs/AlAs/GaAs sample. The results show that, before oxidation, there are two 40-Å-thick intermixing layers, one located between the AlAs sublayer and the GaAs substrate, and the other between the AlAs sublayer and the upper GaAs sublayer. After oxidation, these two intermixing sublayers disappear. The AlAs was oxidized into amorphous Al₂O₃ totally. The surface and interface roughnesses of the sample also decrease after oxidation.