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 afunction of the surface stoichiometry and the Cd chemical potential. We find thatthere 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 potentialμCd, we find the Cd-vacancyand Se-vacancy (2 × 2) structures to be energetically favorable for the Cd-terminated (001) surface at highμCd 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 theSe-terminated CdSe(111) surface almost in the whole region of allowedμCd.