Anodic passivation of SiGe

We have investigated the oxide composition and the electronic behavior of the interface of anodically and thermally oxidized SiGe single crystals and epitaxial layers. X-ray photoelectron spectroscopies show the existence of SiO2, GeO2 and possibly mixed oxide compounds such as SiOGe only in the anodic oxide, whereas the thermally grown oxide layers on SiGe samples consist of pure SiO2. In addition, the Ge enrichment at the interface and relaxation phenomena of the strained SiGe lattice of epitaxial layers, which occurs during thermal treatments, are completely reduced using the anodic treatment. Further, the defect concentration at the interface is reduced after the anodic oxidation as obtained from capacitance-voltage and photoluminescence measurements. (C) 2000 Elsevier Science Ltd. All rights reserved.