Atomistic tight-binding theory of multiexciton complexes in a self-assembled InAs quantum dot

Abstract

We present atomistic tight-binding theory of electronic structure and optical properties of InAs/GaAs self-assembled quantum dots. The tight-binding model includes zincblende symmetry, faceting, and $s{p}^{3}{d}^{5}{s}^{\ensuremath{\ast}}$ atomic orbitals accounting for interband and intervalley couplings. The equilibrium positions of atoms are calculated using valence force field method and modification of the tight-binding Hamiltonian due to strain is accounted for using Harrison's law. The electronic and optical properties of multiexciton complexes are then determined by diagonalizing the many-body Hamiltonian for interacting electrons and holes using the configuration-interaction approach. The calculations of strain distribution approach ${10}^{8}$ atoms while the electron and valence hole single-particle states are calculated by diagonalization of the Hamiltonian matrix with size on the order of ${10}^{7}$. The dependence of predicted electronic and optical properties on InAs/GaAs valence-band offset and InAs absolute valence-band deformation potentials are described. The reliability of the atomistic calculations is assessed by comparison with results obtained from the effective bond orbital model and empirical pseudopotentials method.