Engineering the exciton linewidth in II-VI quantum well structures

Abstract

The excitonic transition in Il-VI quantum well materials has recently been used as the basis for optical modulators and also as the lasing transition at low temperatures. The central aspect in the use of the exciton resonance in optical devices is the understanding of the exciton linewidth. We present a detailed study of the interactions that affect the linewidth in Il-VI semiconductor quantum well materials. The broadening of the resonance with increasing temperature can be controlled by altering the material parameters of the Il-VI structures. In so doing the exciton binding energy can exceed the LO-phonon energy and thereby reduce the homogeneous contribution to the measured linewidth. Efforts to reduce well-width fluctuations in the growth of the Il-VI quantum well structures, which are responsible for the inhomogeneous linewidth, must also be made to a limit where the room temperature Iinewidth is narrow and homogeneously broadened.