EFFECTS OF A DEEP-LEVEL IMPURITY ON OPTICAL-TRANSITIONS OF QUANTUM-WELL HETEROSTRUCTURES

We investigate the effects of a deep impurity center, modeled by a del ta-function potential, on the optical transitions of semiconductor qua ntum welts. Both the exciton binding energy and the oscillator strengt h are calculated as functions of the strength and the center location of the potential, in an attempt to understand the photoluminescence of transition-metal-impurity-doped semiconductor quantum confined struct ures. The calculation shows that a positive impurity placed near the w all of a quantum well can increase the luminescence of the quantum wel l; a negative impurity can greatly raise the luminescence of quantum w ells if it is placed in a suitable spatial range, but it is difficult to use as a dopant from the point of view of device fabrication.