The influence of inter-diffusion on electron states in quantum dots

We calculate the variation of the potential and confinement energy due to inter-diffusion of a spherical InxGa1 - xAs quantum dot embedded in GaAs. The potential drops off more quickly with increasing diffusion length about a quantum dot than is the case for a quantum well. This results in a far more rapid variation of confinement energy for a dot than fur a well, until eventually no electron states are confined in the diffused dot. We show that the spread in confinement energies due to variation in dot size and composition decreases with the diffusion-induced decrease in confinement energy. Our results indicate that the recently observed narrowing of photoluminescence line-width, that occurs as a result of rapid thermal annealing of self-assembled InAs quantum dot structures, can be explained in terms of normal inter-diffusion processes between the dots and surrounding matrix material. (C) 1999 Elsevier Science B.V. All rights reserved.