1ST-PRINCIPLES STUDY OF THE ATOMIC RECONSTRUCTIONS OF ZNSE(100) SURFACES

We examine the reconstructions and surface energies of ZnSe(100) surfaces by first-principles total-energy calculations. The surface energies for the Zn- ana Se-terminated (1 X 1), (1 X 2), (2 X 1), (2 X 2), and Zn-terminated (4X2) reconstructed surfaces consisting of various combinations of dimers and vacancies are determined as a function of coverage and atomic chemical potential. For the Zn- and Se-terminated surfaces, dimerization lowers the energies by 2.12 and 1.08 eV per dimer, respectively. When exchange with bulk Zn or Se reservoirs is considered, a c(2 X 2) Zn-vacancy structure is found to be energetically more favorable than a dimer structure for the Zn-terminated surface, while a (2 X 1) dimer structure is the most favorable one for the Se-terminated surface.