synchrotron radiation photoelectron spectroscopy study of the oxidation of the Ge(100)-21 surface by supersonic molecular oxygen beams

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

synchrotron radiation photoelectron spectroscopy was performed during the oxidation of the Ge(100)-21 surface induced by a molecular oxygen beam with various incident energies up to 2.2 eV from the initial to saturation coverage of surface oxides. The saturation coverage of oxygen on the clean Ge(100) surface was much lower than one monolayer and the oxidation state of Ge was +2 at most. This indicates that the Ge(100) surface is in strong contrast to Si surfaces. The direct adsorption process can be activated by increasing the translational energy, resulting in an increased population of Ge and a higher final oxygen coverage. Our findings will contribute to the fundamental understanding of oxygen adsorption processes at 300 K from the initial stages to saturated oxidation.