Initial oxidation of HF-acid treated SiGe(100) surfaces under air exposure investigated by synchrotron radiation X-ray photoelectron spectroscopy and IR absorption spectroscopy

Abstract

Initial oxidation of HF-acid treated SiGe(100) surfaces under air exposure has been studied by synchrotron radiation X-ray photoelectron spectroscopy (SR-XPS) and highly sensitive infrared absorption spectroscopy with a multiple-internal-reflection geometry (MIR-IRAS). We found that the SiGe surface has been oxidized with a coverage of 0.15 ML in air just after the HF-acid treatment. Angle resolved SR-XPS strongly indicates that a Si-rich layer near the surface is generated in the HF-acid treatment on the SiGe(100) film and the oxidized part is mainly composed of SiO 2. It was also found the other unoxidized part is gradually oxidized in air. The MIR-IRAS measurements indicate that the oxidation of the hydrogenated SiGe surfaces by HF-acid treatment in air takes place by the selective oxidation of backbonds of the surface Si despite of the stable hydrogen passivation.