Ab-initio study of new Ga-rich GaAs(001) surface (4 × 4) reconstruction

Atomic and electronic structures for a number of GaAs(001) surface geometries were studied within the density functional theory (DFT) in order to re-examine the energy stability of surface reconstructions in the Ga-rich limit. The (2 × 4) mixed-dimer model developed for InP(001)-(2 × 4) surface was adopted for Ga-rich GaAs(001)-(2 × 4) surface. It is shown that the energetically favored Ga-rich (2 × 4) reconstructions are stabilized by dimerized Ga and As atoms. Our DFT calculations predict the coexistence of (2 × 4) and (4 × 4) reconstructions on GaAs(001) in the Ga-rich limit.