Surface atomic geometry and electronic structure of II–VI cleavage faces

Abstract

Recent models of the electronic structure and surface atomic geometries on wurtzite-structure CdS and CdSe have been extended to encompass zinc-blende structure CdTe. The driving force for the surface reconstruction of the cleavage faces of all these materials is the lowering in energy of a band of anion dangling bond surface states accompanied by their acquisition of back-bonding character. The resulting reconstructed surface is characterized by the eigenvalue spectrum associated with this band of states as well as the atomic geometries. The predicted geometries for CdTe(110), CdSe(101̄0), and CdSe(112̄0) are in good correspondence with low-energy electron diffraction (LEED) and low-energy positron diffraction intensity analyses. The calculated surface state eigenvalue spectra are compared with recent angle-resolved photoemission spectra (ARPES) for CdTe(110) and CdSe(101̄0). The main features of the ARPES measurements are reproduced by the calculated eigenvalue spectra. The predicted atomic geometry for CdTe(110) corresponds well both with prior predictions for ZnSe(110) and ZnS(110), and with LEED experimental surface structures indicating that these surfaces exhibit a universal structure in which the independent surface structural parameters scale linearly with the bulk lattice constant.