Signatures of antibonding hole ground states in exciton spectra of vertically coupled quantum dots in an electric field

We study exciton energy spectra in a pair of vertically coupled self-assembled quantum dots in external electric field. We perform a systematic comparison of the four-band Luttinger Kohn modeling producing an antibonding hole ground state with the single valence-band approximation in which the hole ground state has the bonding character. We find that the single-band approximation remains relevant for description of the electric field dependence of the photoluminescence spectrum for interdot barrier thickness of 7 nm or larger. We explain that for thinner barriers the antibonding character of the hole orbital can be deduced from the ground state recombination probability as a function of the electric field.