Destruction and appearance of surface metallization in the system K/Si(111) 7×37

Qualitative changes are observed in the character of the surface electronic structure accompanying the adsorption of potassium on a Si(111) 7×7 surface. The metallic conductivity of the Si(111)7×7 surface is destroyed at the very early stages of adsorption. A new band induced by the adsorption of potassium is observed below the Fermi level. It is found that the K/Si(111)7×7 interface is semiconducting right up to saturating coverage. A surface transition from an insulating into a metallic state, accompanied by pinning of the Fermi level, is observed in the region of saturating coverage. Metallic conductivity arises in the adsorbed potassium layer as a result of the development of an induced surface band at the Fermi level. Pis’ma Zh. éksp. Teor. Fiz. 66, No. 1, 27–30 (10 July 1997)