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

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 SiO2. 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.