Theoretical studies of the electronic structure of semiconductor surfaces

Methods developed by the author and J.A. Appelbaum have been used to examine the electronic Structure of semiconductor surfaces in a variety of situations. These essentially first principles calculations self-consistently determine the potential in a surface region several atom layers thick which continuously join to a semi-infinite bulk region whose self-consistent potential is previously determined. Model potentials adjusted to fit bulk and atomic levels represent the ion cores, and a local functional of the density represents the exchange and correlation potential. Electronic states are found in a mixed real-space Fourier-space representation using a transfer matrix technique. A primary emphasis in the problems studied has been to relate features in experimentally accessible surface spectra to hypothesized rearrangements in the atomic geometry and chemical bonding at the surface. Studies of the unreconstructed and reconstructed clean Si(100) surface and of H chemisorption on several Si surfaces will be described as examples of the utility of the methods.