The energy shell structure of a single exciton confined in a self-assembled quantum dot (QD), including excited states, is studied in a regime where the direct Coulomb attraction energy is comparable to the kinetic energy of the carriers. This is achieved via magnetophotoluminescence excitation spectroscopy experiments, where a magnetic field applied perpendicular to the plane of the QD is used to reveal the angular-momentum content of energy shells. The absorption spectrum of the QDs is modeled, and comparison with experiment allows us to relate the observed transitions to interband QD bound-state transitions. The blueshift of the absorption peaks compared to the emission peaks is then interpreted in terms of many-body interactions, and we show that for a highly symmetric situation, the observed energy difference gives a direct measurement of the extra exchange energy gained upon addition of an extra exciton in the QD.

We report on photoluminescence measurements from a single InAs/GaAs quantum dot in magnetic fields up to 28 T. Mesa-patterned structure has been used to limit the number of investigated dots. Three pairs of Zeeman-split emission lines with the same effective g*-factor and diamagnetic shift have been observed. The attribution of the lines to recombination of a neutral exciton, a biexciton, and a charged exciton is discussed.

A set of self-assembled InAs/GaAs quantum dot (QD) samples annealed at various temperatures for 30 s was studied using magneto-photoluminescence up to 28 T. Blueshifts increasing with annealing temperature, due to Ga-As interchange at the QD-barrier interface, are correlated with a reduction in inhomogeneous broadening and a reduction in inter-sublevel spacing. These new sample properties allow us to obtain clear crossing patterns closely matched with Fock-Darwin diagrams where the field applied perpendicular to the QD plane lifts the state degeneracies. In the limit that in-plane electron and hole wavefunction extension is the same, the splitting of the p-shell with magnetic field is inversely proportional to the in-plane exciton reduced mass. We use this to obtain the evolution of the latter with intermixing, and compare with predictions of single-particle k * p calculations.