Binding energy of an off-center shallow donor D- in a spherical quantum dot

The binding energy of a negatively charged hydrogenic impurity with on- and off-center positions in a spherical Gaussian quantum dot was calculated with the configuration interaction method. Our calculations show that E-b is always positive for on-center impurities with a maximum near to the radius for one-electron stability of the potential well R-c. For off-center positions the binding energy can assume negative values within a range of the quantum dot radius, thus indicating the instability of the system. (C) 2010 Elsevier B.V. All rights reserved.