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

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 (pz) is observed as additional holes are added to the dot. A comparison with calculations reveals that this reduction (Δpz/e∼15–20%) is accompanied by a significant lateral expansion of the hole View the MathML source and contraction View the MathML source 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.