Density functional study of the electronic properties of the Si (001)2x1-potassium surface

We have studied the interaction of alkali metals with Si(001)-2xl surface within the density functional formalism using the SCF pseudopotential method. Some experimental data which are subject to misinterpretation, coupled with our lack of knowledge about the exact adsorption structure, have led to some controversy about the nature of the K-Si bonding. We provide a resolution of some of these problems. We show that the active intrinsic surface states play a crucial role in determining the bonding between K and S(00 l)-2x 1. In particular, the overlayer metallization is suppressed even up to saturation coverages for this metal-semiconductor system