Comparative ab initio pseudopotential studies of group V overlayers on Si(001)

Abstract

We present a comparative theoretical study of a single-monolayer coverage of the group V elements P, As, Sb and Bi on the Si(001) surface. The generic surface reconstruction, due to formation of symmetric overlayer dimers, is considered and a first-principles pseudopotential method is used. In addition to presenting well-relaxed structural data, we identify chemical trends in geometry, bonding and electronic structure in moving down the group V column of the periodic table. Overlayer-induced distortion of the substrate is found to decrease with increasing overlayer atomic number. In general, P and As overlayer systems share many similarities, while Sb and Bi form another such natural pair. A novel feature of group V overlayers is that the bonding and occupied antibonding states formed by the dangling bonds lie very close in energy.