Excitonic and biexcitonic properties of single GaN quantum dots modeled by 8-bandk⋅ptheory and configuration-interaction method

Abstract

Excitons and biexcitons in GaN/AlN quantum dots ͑QD͒ were investigated with special emphasis on the use of these QDs for single-photon source applications. The theoretical methodology for the calculation of singleparticle states was based on 8-band strain-dependent envelope function Hamiltonian, with the effects of spinorbit interaction, crystal-field splitting, and piezoelectric and spontaneous polarizations taken into account. Exciton and biexciton states were found using the configuration-interaction method. Optimal QD heights for their use in single-photon emitters were determined for various diameter to height ratios. The competition between strong confinement in GaN QDs and internal electric field, generally reported in wurtzite GaN, was also discussed, as well as its effect on appearance of bound biexcitons.

Size dependent biexciton binding energies in GaN quantum dots

“…The binding of the biexciton is essentially an effect of the Coulomb correlations, but the strong built-in electric field in GaN QDs results in large h-h and e-e repulsive interactions, which cannot be overcome by the attractive e-h interactions and the Coulomb correlations. 24 However, the Coulomb correlations are most significant in weakly confined QDs, and they can usually be neglected in the strong confinement regime. 26 The large experimental values of the biexciton binding energies up to 6.5 meV, as estimated for the GaN/Al(Ga)N QDs in this work, can thus be associated with the shallow exciton confinement potentials of these QDs.…”

Symmetry reduction in multiband Hamiltonians for semiconductor quantum dots: The role of interfaces and higher energy bands

“…[4][5][6][7][8][9][10][11][12][13][14][15][16] While certain physical effects in QDs can be qualitatively understood solely based on discreteness of energy levels or using simple particle-in-a-box models, for most purposes an accurate treatment of the electronic structure of QDs is necessary. Typical self-assembled QDs have millions of atoms and therefore the methods based on ab initio density functional theory, the workhorse of modern electronic structure calculations, are far beyond the reach of present day computational capabilities.…”

Quantum confinement effects in gallium nitride nanostructures:ab initioinvestigations

“…Theoretical investigations of GaN nanodots have used a range of computational methods including k·p theory, [13,14] empirical forcefields, [15] tight-binding [16,17] and density functional theory. [18] Many of these investigations use approximate or semiempirical methods, and investigate the properties GaN nanodots mixed with other III-V nitrides.…”

“…AlN or InN, to investigate properties such as strain effects or exciton behaviour. [13,14] Classical molecular dynamics has been used to investigate the thermal conductivity of GaN quantum dots coated with AlN. [15] Semi-empirical tight-binding calculations have been used to study optical transitions in InGaN-GaN quantum dots [16] and the affect of Mg doping in GaN nanodots.…”