Electronic properties of the Bi/Si(100) interface

An investigation of the electronic properties of the Bi/Si(100) interface in the early growth stage is presented. Bi-induced occupied electronic states and absorption features are determined through the complementary UV photoemission spectroscopy and high resolution electron energy loss spectroscopy in the energy gap region. The interface is clearly semiconducting at half-monolayer coverage, with a surface energy gap of 1.1 eV, greater than that of the clean Si(100) surface. This behavior can be understood by considering the saturation of the topmost layer silicon dimer dangling bonds by the Bi adatoms. The interface assumes a weak semimetallic character at the completion of one monolayer, probably because of the formation of Bi-Bi adatom bonds. Space charge layer formation and a slight downward band bending. (C) 1998 Elsevier Science B.V. All rights reserved.