Application of semi-ab initio method of band structure calculation to semiconductor superlattices

We used an efficient direct-space orthogonalized linear combination of atomic orbitals method to calculate the band structures of most common elemental, III–V and II–VI semiconductors, obtaining correct locations and magnitudes of the band gaps. The atomic-like minimal basis and the atomic-like potentials obtained from these calculations can be used to calculate the band structures of semiconductor superlattices. As an example of such an application, we show the results of calculations on 100 Si bilayers (313 Å in width) randomly stacked in the 111] direction. This structure represents a realistic one-dimensional model system with off-diagonal disorder in the z-direction and hexagonal translational symmetry in the x-y plane. Highly localized states at both the conduction band and the valence band edges are identified and analyzed. These electron states are compared with those obtained from similar calculations on perfect Si-bilayers of same width as in diamond lattice and those containing intrinsic and extrinsic types of stacking faults.