Electronic structure of (InAs)m(GaAs)m(m=1–7) strained superlattices

The electronic structure of (InAs${)}_{\mathrm{m}}$(GaAs${)}_{\mathrm{m}}$ (m=1–7) strained superlattices is studied with use of the self-consistent pseudopotential method. The atom positions are determined by using the valence-force-field approach. The calculated band gaps are in good agreement with the experimental results. The weak dependence of the band gaps on layer thickness is due to the s-like character of the ${\Gamma }^c$ state. The conduction electron extends over the superlattice. In contrast, the hole distribution tends to be localized in the InAs regions. From the investigation of the self-consistent potential and charge-density distribution, it is found that the lattice-mismatch effect relaxes over a few atom layers near the interface. The charge is transferred from the GaAs region to the InAs region. This transferred charge is stored at the interface.