Systematic reduction of the permanent exciton dipole for charged excitons in individual self-assembled InGaAs quantum dots

Abstract

The nature of the few particle wavefunctions for neutral and positively charged excitons is probed in individual InGaAs quantum dots using Stark-effect perturbation spectroscopy. A systematic reduction of the vertical component of the permanent excitonic dipole ( p z ) is observed as additional holes are added to the dot. A comparison with calculations reveals that this reduction (Δ p z /e∼15–20%) is accompanied by a significant lateral expansion of the hole (∼2 nm) and contraction (∼1 nm) of the electron wavefunctions. We suggest that this lateral redistribution of the charged exciton wavefunctions provides an optical means to probe the lateral composition profile of the dot.