Photoemission study of GaSb(111) and Ge adsorbed on GaSb(111) surfaces

Abstract

Clean - surfaces, prepared by cycles of ion bombardment and annealing, and GaSb(111)A with various Ge coverages were investigated using low-energy electron diffraction and different modes of photoelectron spectroscopy with synchrotron radiation. Valence band energy distribution curves, and constant-initial-state, and constant-final-state spectra obtained for the clean surface exhibit strong resonances at 19.2 and 19.7 eV which are associated with surface Ga and core excitons. The amplitudes of the resonances decrease monotonically with increasing adsorbate layer thickness. At a Ge coverage of 1.9 Å the resonances disappear, and concomitant changes in the adsorbate and substrate core-level spectra are observed. The data provide detailed information about the chemical bonding between adsorbate and substrate atoms, and indicate that the growth mode is primarily layer by layer but is not epitaxial.