Adsorption of potassium on the ideal Si(111) surface

We present the results of self-consistent pseudopotential total-energy and charge-density calculations for the potassium-covered ideal Si(111) surface. It is found that K adsorbed on the -bonded Si(111)-(2×1) surface is less stable by 0.3 eV as compared to adsorption on the ideal surface, suggesting that the -bonded surface is metastable upon K adsorption. The overlayer binding energy is estimated to be 3.4 eV. However, at monolayer coverage of the metal, the bonding is found to be ionic on both the ideal and -bonded reconstructed surfaces. No evidence for the overlayer metallization is detected at such coverages, presumably due to the presence of active dangling bonds and strong ionic bonding. © 1988 The American Physical Society.