First-principles study of Sb-stabilized GaSb(001) surface reconstructions

We report results of ab initio total-energy and electronic- structure calculations for the Sb-stabilized GaSb(001) surface. We consider different reconstruction models proposed in the literature on the basis of experimental observations in typical GaSb growth conditions and present the T=0 surface stability diagram. We found that dimer-based (4 x 3) reconstructions are favored over widely proposed (1 x 3)/c(2 x 6) models that have a similar structure, but do not satisfy the electron counting rule. We discuss also the stability of the beta 2(2 x 4) reconstruction for comparison with the As-based GaAs(001) and InAs(001) surfaces that present this phase in a wide range of surface preparation conditions. We predict the surface band structure of the GaSb(001) stable configurations and identify the nature of the surface bands. All the (4 x 3) reconstructions turned out to be semiconducting with an energy gap slightly smaller than the GaSb bulk value.