We investigate the electronic structures of the inhomogeneous quantum dots within the framework of the effective mass theory. The results show that the energies of electron and hole states depend sensitively on the relative magnitude $\eta$ of the core radius to the capped quantum dot radius. The spatial distribution of the electrons and holes vary significantly when the ratio $\eta$ changes. A quantum-confinement-driven type-II–type-I transition is found in ${\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}/\mathrm{A}\mathrm{l}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}$-capped quantum dot structures. The phase diagram is obtained for different capped quantum dot radii. The ground-state exciton binding energy shows a highly nonlinear dependence on the innner structures of inhomogeneous quantum dots, which originates from the redistribution of the electron and hole wave functions.

• Received 30 April 1999

DOI:https://doi.org/10.1103/PhysRevB.61.4743