Adsorption of potassium on a Si(111) surface

The adsorption of potassium on several sites (T₁, T₄, H₃) of a Si(111) surface is studied using the extended Hückel method and cluster models. The results show that the chemisorption energy on the T₄ site is almost equal to that on the H₃ site for an ideal surface. However, the analysis of chemical bonding of adatoms on a Si surface suggests that the chemisorption of adatoms might induce a kind of reconstruction on the Si(111) surface. Rough calculations for the adsorption on this reconstructed surface are carried out. In this paper, charge transfer, density of states and characterization of the bonds between the adatom and substrate Si atoms are also investigated in detail.