Alkali metal adsorption on the Si(111)7×7 surface

Abstract

Alkali metal (K,Cs) adsorption on the Si(111)7×7 surface has been investigated with the field ion-scanning tunneling microscope. At the initial coverage, K(Cs) atoms adsorb mainly at the on-top site of the center adatoms and are ionized. Some of the adsorbed alkali metal atoms form clusters (often trimers), which have more covalent character with back-donation of the charge distribution, and those clusters become the dominant species on the surface with increasing coverage. When the Si(111)-K surface is heated at 300 °C, a new 1×3 phase grows as islands which are made of incommensurate linear chains with misfit defects.