We report on the magnetic field dispersion of the exciton spin-splitting and diamagnetic shift in single $\mathrm{In}\mathrm{As}∕\mathrm{Ga}\mathrm{As}$ quantum dots up to $B=28\mathrm{T}$. We have found substantial differences between field evolution of the emission from tall ($4\mathrm{nm}$ height) and flat ($2\mathrm{nm}$ height) dots. Strongly nonlinear spin-splitting is observed in the former case, while in the latter case the nonlinearity is much weaker. The diamagnetic shift of the ground-state emission can be explained in terms of geometric size of the dots. While it can be approximated by a quadratic field dependence in dots of large confining potential, a substantial linear contribution must be included to account for the diamagnetic shift in dots of weaker confinement.

• Received 10 March 2006

DOI:https://doi.org/10.1103/PhysRevB.74.075310