Native Oxidation Growth on Ge(111) and (100) Surfaces

Abstract

We studied the native oxide growth on Ge(100) and (111) surfaces treated by HCl and HF cleaning in clean room air by high-resolution X-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry (SE). The native oxidation of both HCl- and HF-last Ge(100) surfaces exhibited likely layer-by-layer fashion. The native oxide growth of the n-Ge(100) was significantly faster than the p-Ge(100) at the early stage of native oxidation. This can be explained by the formation of an O2- ion through free electron transfer from the Ge to the adsorbed O2 molecules, which induces the surface electric field that can initiate the oxidation. In the case of different crystallographic orientations, the oxide rate of the Ge(100) surface was faster than that of the Ge(111) surface. This might be attributed to larger open space of the Ge(100) surface than that of the Ge(111) surface.