The surface structure and the insulator-metal transition of the Na overlayer on the Na-induced Si(111)3 × 1 surface was studied using scanning tunneling microscopy and spectroscopy. The results suggested that this reconstruction was caused by the conversion of the 7 × 7 structure to the bulk-terminated 1 × 1 structure and a monolayer of Na adatoms arranged in the 3 × 1 periodicity at a coverage of 2/3 monolayer. When oxygen was adsorbed on this surface the surface morphology hardly changed up to several hundred Langmuir. This surface passivation arose from the removal of Si dangling bonds by the Na adatoms. Upon further Na evaporation onto the Si(111) 3 × 1 Na surface at room temperature we could grow an epitaxial Na double layer and a multilayer through an island formation. Oxygen adsorption on the Na double layer, and a multilayer resulted in cluster formation. This result indicated that more than two layers of alkali overlayer was needed to promote the chemical activity on a silicon surface.
|Number of pages||5|
|Journal||Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers|
|Issue number||3 B|
|Publication status||Published - 1993 Mar|
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)