Theoretical study of the atomic and electronic structure of the c-4 × 4 reconstructed GaAs(100) surface

Abstract

The c-4 × 4 reconstruction of the As(100) face of GaAs is examined using an energy-minimization approach. Other structures with 1 × 1, c-2 × 2 and p-2 × 2 periodicities are also examined in this study. The calculations predict that dimerization of surface As atoms is energetically favorable; however, structures with only one type of dimer per unit cell are found to be unstable. A four atom unit cell with two inequivalent dimers is the minimum size necessary for an adequate description of the surface atomic and electronic properties. The C-4 × 4 surface is suggested to consist of equal numbers of symmetric and asymmetric As dimers.