Characterization of Oxide Layers of Bulk Si_1-xGe_x

Abstract

Bulk crystals of Si_0.4Ge_0.6, grown using the vertical Bridgman method, were oxidized at 800 °C for 1 h using oxygen in dry oxidation and a stream of de-ionized water in wet oxidation. Single-like and polycrystalline Si_0.4Ge_0.6samples were used. The oxidized samples were analyzed using x-ray photoelectron spectroscopy to determine the chemical states of the Si and Ge in the oxide. In the sample oxidized using a dry ambient, the oxide layer consisted mainly of SiO₂, and GeO₂ formed the subsurface area only. This can be accounted for by the differences in the formation of the free energies of the SiO₂ and GeO₂. In wet oxidation, the oxide layer had a mixed structure consisting of SiO₂ and GeO₂. To understand the oxide formation mechanisms in the wet oxidation process, an introduction of a chemical bond manipulation explained the formation of the mixed structure.