Surface electronic structure of K on Si(111)2×1 as a function of potassium coverage

We have studied the room-temperature deposition of potassium on the cleaved Si(111)2×1 surface with direct and inverse photoemission. In contrast to the analogous cesium case as well as the prediction of a total-energy calculation, we find that the 2×1 reconstruction is stable against K adsorption. The measured energy dispersions of the unoccupied surface-state band for about half- and full-monolayer coverages indicate a crossing of the Fermi level along the Jazimuth, suggesting a metallic substrate surface, as calculated by Ciraci and Batra. © 1990 The American Physical Society.