Scanning Tunneling Microscopy Study on the Reaction of Oxygen with Clean Ge (001) Surfaces

摘要

Chemical reaction of oxygen to the clean Ge surfaces has been investigated by in situ scanning tunneling microscopy. The Ge surface structure varied sensitively to the oxygen partial pressure and the substrate temperature during the reaction. The observed phenomena can be categorized typically into the modes of either etching or oxidation, and the transient mode including both processes, by analyzing the surface structures on an atomic scale. The etching (oxidation) tends to proceed at higher (lower) temperature and lower (higher) oxygen pressure. The surface step was found to act as a preferential reaction site for the etching whereas no remarkable changes were detected at the step site during the oxidation. The oxygen reactivity on Ge will be discussed compared to the Si case.