Direct observation of ordered structures during oxidation of Si(111)

Abstract

Variable-temperature ultra high vacuum scanning tunnelling microscopy (VTUHVSTM) has been employed to study the initial stage of Si(111) oxidation. By taking advantage of the in-situ arrangement of the experiment, we are able to constantly monitor the surface structure during the whole oxidation process at elevated temperatures. Ordered structures of oxides from a submonolayer to a full monolayer were observed at atomic level. Our preliminary results may give a clue to one of the fundamental issues of silicon technology: why amorphous silicon dioxide can form a perfect interface with the crystalline silicon substrate.