Donor states in coupled quantum dots

Electronic properties of three donors in three quantum dots are examined as we change the donor configurations (maintaining one donor per dot), vary the thickness of the barriers between the dots, impose an anisotropic confinement, and apply an external dc electric field. A scaled Kohn-Sham formalism is applied to treat the electron-electron interaction self-consistently within the local-density approximation. We compare the binding energies of the centered, molecular, and random donor configurations and find that the binding energy is the largest for the centered donor configuration due to the modulation by the boundary condition. We also find that dipole matrix elements can be enhanced if confinement or an external electric field increases the overlap between the initial and final states, and sustains their atomic characters of opposite parity. In addition, we demonstrate the importance of a self-consistent treatment of the electron-electron interaction in determining the ground-state binding energies and charge distributions of the donor states. © 1994 The American Physical Society.