First-principles studies of the atomic reconstructions of CdSe (001) and (111) surfaces

Abstract

We have performed the first-principles total-energy calculations to investigate (2 × 1), (1 × 2), (2 × 2), (4 × 2) and (2 × 4) reconstructions of Cd- and Se-terminated CdSe(001) and (111) surfaces as a function of the surface stoichiometry and the Cd chemical potential. We find that there exist Cd dimers on the (001) surface and Se tetramers on the (111) surface. Comparing surface formation energies as a function of the Cd chemical potential μCd, we find the Cd-vacancy and Se-vacancy (2 × 2) structures to be energetically favorable for the Cd-terminated (001) surface at high μCd and Se-terminated (001) surface at low μCd, respectively. In contrast, an Se-tetramer (2 × 4) structure is more favorable than the vacancy structure for the Se-terminated CdSe(111) surface almost in the whole region of allowed μCd. © 2009 IOP Publishing Ltd.