Reconstructions and surface facets of the GaAs(112)A and (112)B surfaces: First-principles DFT supercell calculations

The morphology and energy of the polar GaAs(112)A and (112)B surfaces have been studied by DFT supercell methods. The stability of different reconstruction patterns in the allowed range of the chemical potentials is calculated for the two planar surfaces as well as for the facetted surfaces, where for both surfaces faceting into either {(111)A/B, 2 × (110), (113)A/B} or {(111)A/B, 2 × (110), 2 × (124)A/B} is investigated. Reconstruction patterns and absolute surface energies of the (124)A and B surfaces are calculated for the first time. For both surfaces the decomposition into facets is energetically more favourable than the planar surfaces in the whole range of the allowed chemical potentials. In both cases the facets which contain the (113) surfaces are more stable than those with (124) surfaces. te surface energies of polar surfaces, which are not directly calculable, are derived from calculable absolute surface energies of non-polar surfaces by the infinite triangular prism method.