Аннотация:
Detailed information on GaAs oxide properties is important for solving the problem of passivating and dielectric layers in the GaAs-based electronics. The elemental and chemical compositions of the native oxide layer grown on the atomically clean surface of an $n$-GaAs (100) wafer etched by Ar$^+$ ions have been studied by synchrotron-based photoelectron spectroscopy. It has been revealed that the oxide layer is essentially enriched in the Ga$_2$O$_3$ phase which is known to be a quite good dielectric as compared to As$_2$O$_3$. The gallium to arsenic ratio reaches the value as high as [Ga]/[As] = 1.5 in the course of oxidation. The Ga-enrichment occurs supposedly due to diffusion away of As released in preferential oxidation of Ga atoms. A band diagram was constructed for the native oxide nanolayer on the $n$-GaAs wafer. It has been shown that this natural nanostructure has features of a $p$–$n$ heterojunction.