The K/(100)Si 2 x 1 interface was investigated by using various techniques. The adsorption sites for K were determined by using Xe titration and Xe photo-electron spectroscopy. It was found that the K atoms were preferentially adsorbed between the rows of dimers of the 2 x 1 reconstruction (cave-valley) sites. By using work-function, thermal desorption, and ultra-violet photo-emission methods, it was demonstrated that the K overlayer had a metallic nature at coverages of more than 0.5 of a monolayer. Charge transfer from K to Si gave rise to a reduction in the local work function at sites which were close to K atoms. Long-range reduction affected the whole surface at coverages of more than 0.2 of a monolayer.

E.G.Michel, P.Pervan, G.R.Castro, R.Miranda, K.Wandelt: Physical Review B, 1992, 45[20], 11811-22