Structure of III-Sb(001) Surfaces Under Extreme Sb-rich Conditions

We use density functional theory to study the structure of III-Sb(001) (III = Al or Ga) growth surfaces. Various reconstruction models are considered to construct the surface stability diagram under different III-Sb growth conditions. We found that AlSb surface stability diagram identifies experimentally observed surface reconstructions quite well. For GaSb, however, all $(n\times 5)$-like reconstructions proposed to date have too high surface formation energies compared to the ones with wrong periodicities and thus cannot adequately model the structures observed experimentally under extreme Sb-rich growth conditions. Our results indicate that the existing reconstruction models for GaSb(001) surface require revisiting and demonstrate the need for a better reconstruction model.