Valence-band photoemission from GaAs(100)-c(4x4) - art. no. 085309

The energy distributions of photoelectrons emitted from the c(4 x 4) recons tructed GaAs(100) surface are carefully analyzed within the one-step model of photoemission, thus demonstrating that such calculations work for large unit cells. It is used for detailed interpretation of published and new ang ular resolved He I experimental data. Surface-related features are found an d their localization and symmetry are determined. Backfolding of the electr on energy bands and its splitting at the reduced Brillouin zone's boundarie s lead to smaller energy dispersion of electron surface states and resonanc es. The experimentally observed longer period of a surface resonance than t hat corresponding to the translation symmetry of the reconstructed surface is confirmed and explained. The existence of two surface states near the up per valence-band edge is verified. One major difference between the theory and the experiment is found that cannot be explained by means of the one-st ep model for a perfectly reconstructed surface.