Electronic band structure of the (GaAs)1/(InAs)1 (111) superlattice

We present a first-principles calculation of the electronic band structure of (GaAs)1/(InAs)1 (111) superlattice, performed by using ab initio norm-conserving pseudopotentials. The folding in the smaller Brillouin zone and the new symmetry properties of the electronic states have been thoroughly investigated by a comparison with the band structure of the corresponding disordered alloy treated within the virtual-crystal approximation. The interactions between the folded states giving rise to energy splittings and electronic charge localization on given layers have been analyzed at the high-symmetry points. The effects of the new ordering potential, introduced by differentiating the two cations in the virtual crystal, and of the strain potential—arising when the superlattice is subjected to a lateral strain on the (111) planes—are separately investigated. We find a strong charge localization in the first two conduction states at the Gamma point and a considerable minimum-band-gap redu...