DESTRUCTION AND APPEARANCE OF SURFACE METALLIZATION IN THE SYSTEM K SI(111)7X7/

Qualitative changes are observed in the character of the surface elect ronic structure accompanying the adsorption of potassium on a Si(1 1 1 ) 7 X 7 surface. The metallic conductivity of the Si(1 1 1)7 X 7 surfa ce is destroyed at the very early stages of adsorption, A new band ind uced by the adsorption of potassium is observed below the Fermi level, It is found that the K/Si(1 1 1)7 X 7 interface is semiconducting rig ht up to saturating coverage, A surface transition from an insulating into a metallic state, accompanied by pinning of the Fermi level, is o bserved in the region of saturating coverage, Metallic conductivity ar ises in the adsorbed potassium layer as a result of the development of an induced surface band at the Fermi level. (C) 1997 American Institu te of Physics.