Synchrotron radiation photoelectron spectroscopy study on surface oxides at Ge(100)-21 surface

Yoshigoe, Akitaka ; Okada, Ryuta; Teraoka, Yuden; Iwai, Yutaro*; Yamada, Yoichi*; Sasaki, Masahiro*

Germanium (Ge) has received much attention as promising substitute channel material for future electronic devices. In this conference, we report the nature of oxides of Ge(100)-2x1 surface fabricated with pure oxygen gas (O) at 300 K. Surface oxide and its evolution were observed by in-situ synchrotron radiation photoelectron spectroscopy (SR-XPS) measurement during oxidation from the very initial stages to the maximum oxide coverage. Incident (O) energy dependence of oxides was investigated using supersonic molecular beam techniques. We found that saturation oxide coverage on Ge(100)is much less than one monolayer. SR-XPS measurements clearly demonstrated that the maximum oxidation number of Ge in saturation region was as small as 2. The population of the Ge2+ and oxygen coverage increased with increasing the incident (O) energy. Our findings reveal the significant difference between the nature of surface oxides of Ge and Si.