Interface electronic structures in an InAs/GaAs lattice-mismatched system

Abstract

Interface electronic structures in an InAs/GaAs lattice-mismatched system are studied, and strain effects are investigated. The electronic structures are examined under three different strain conditions characterized by the lattice constant parallel to the interface. Investigations of strain effects on the interface electronic properties give new information on band discontinuity and interface-state properties. The electronic structures are calculated by use of the self-consistent pseudopotential method. The valence-force-field approach is employed in determining the atom positions. Deep interface states are found about 10 eV below the top of the valence bands, independent of the interface-strain conditions. It is found that the strain conditions and the symmetry change at the interface are not important factors in forming interface states. The important factor is charge modification near the interface. Band discontinuities and carrier confinements greatly depend on strain. Interface-strain relaxation influences charge transfer from the GaAs region to the InAs region. It also affects the band lineup. A correlation is found between band lineup and interface dipole.