Self-consistent pseudopotential calculation for the electronic structure of a (InAs)1(GaAs)1monolayer superlattice

Abstract

The electronic structure of a (InAs${)}_1$(GaAs${)}_1$ monolayer superlattice is calculated by use of the self-consistent pseudopotential method, and the ionic pseudopotential of In is determined. The InAs/GaAs system has a large lattice mismatch (7%). Strong evidence for the mismatch effect is seen in the electronic structure. The threefold-degenerate level at ${\Gamma }^v$ seen in InAs or GaAs splits into two levels. The conduction-band Γ valley is anisotropic in nature with an estimated perpendicular effective mass of 0.061$m_0$ and a parallel mass of 0.053$m_0$. The energy gaps also greatly depend on the difference in bond length between In–As and Ga–As. The characters of the $Z_x^c$ and $R^c$ levels are drastically altered as a result of this difference. The band gap is estimated by determination of the atomic configurations with use of the valence force-field approach. The obtained gap of 0.84 eV is in fairly good agreement with the previously reported experimental result of 0.77 eV. In addition, charge transfers occur from the Ga–As bonds to the In–As bonds.