Effect of a parabolic potential on the impurity binding energy in spherical quantum dots

The binding energy of a shallow hydrogenic impurity in a spherical quantum dot (QD) with square-well potential (SWP) is calculated using a perturbation method. The same is also calculated assuming the dot to have an isotropic parabolic potential (PP). The calculated binding energies are computed for GaAs QD as a function of the dot size for different impurity positions, and also as a function of the donor position for different dot sizes. The results show that the impurity binding energies increase with a reduction in the dot dimension. The binding energy is also found to depend on the location of the impurity, and the same is maximum for the on-centre impurity. The comparison of the two impurity states show that the binding energy is lower in the case of the parabolic confinement. (C) 1998 Elsevier Science B.V. All rights reserved.