DONOR STATES IN COUPLED QUANTUM DOTS

Electronic properties of three donors in three quantum dots are examin ed as we change the donor configurations (maintaining one donor per do t), vary the thickness of the barriers between the dots, impose an ani sotropic confinement, and apply an external dc electric field. A scale d Kohn-Sham formalism is applied to treat the electron-electron intera ction self-consistently within the local-density approximation. We com pare the binding energies of the centered, molecular, and random donor configurations and find that the binding energy is the largest for th e centered donor configuration due to the modulation by the boundary c ondition. We also find that dipole matrix elements can be enhanced if confinement or an external electric field increases the overlap betwee n the initial and final states, and sustains their atomic characters o f opposite parity. In addition, we demonstrate the importance of a sel f-consistent treatment of the electron-electron interaction in determi ning the ground-state binding energies and charge distributions of the donor states.