Ab initio atomistic thermodynamics calculations of the initial deposition of epitaxial MgO film on GaAs(001)-beta 2(2 x 4)

Abstract

Ab initio calculations were performed to investigate the initial deposition of epitaxial MgO on GaAs(001)-beta 2(2 x 4). The differences between the chemical bonding of Mg-As and O-As were characterized by the adsorption energies of atomic O and Mg at several symmetrically distinct sites, and O bonding was substantially stronger than that of Mg. Thermodynamics were analyzed through the introduction of environmental chemical potentials simulating in situ growth conditions by the sputtering of a stoichiometric MgO target. A surface phase diagram was generated under Mg and O environments with constrained equilibrium, and the results explained the initial formation of an epitaxial MgO phase on GaAs(001)-beta 2(2 x 4). (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4789952]