Deep level transient spectroscopy and pseudopotential superlattice calculation for an InAs monolayer embedded in GaAs

We present deep level transient spectroscopy measurements and pseudopotential supercell calculations for InAs monolayers embedded in GaAs. The insertion of InAs MLs into GaAs generates two states in the fundamental gap of the GaAs host material, namely, MV above the valence band edge and MC below the conduction band edge. The density distribution shows that these states MV and MC are localized at the InAs layer. We determine the distance between MV and the valence band edge as well as that between MC and the conduction band edge. In addition, the thermal activation energies EMV and EMC and the photo cross section sn o of the state MC are measured. The value of the optical threshold derived from sn o agrees well with the calculated onset of a continuum of conduction band states. Our calculations are based on transferable pseudopotentials for InAs and GaAs. The lattice relaxation of the InAs layer is included consistently, and the influence of the strain and the exchange of atomic pseudopotentials is discussed.