ENGINEERING THE EXCITON LINEWIDTH IN II-VI QUANTUM-WELL STRUCTURES

The excitonic transition in II-VI quantum well materials has recently been used as the basis for optical modulators and also as the lasing t ransition at low temperatures. The central aspect in the use of the ex citon resonance in optical devices is the understanding of the exciton linewidth. We present a detailed study of the interactions that affec t the linewidth in II-VI semiconductor quantum well materials. The bro adening of the resonance with increasing temperature can be controlled by altering the material parameters of the II-VI structures. In so do ing the exciton binding energy can exceed the LO-phonon energy and the reby reduce the homogeneous contribution to the measured linewidth. Ef forts to reduce well-width fluctuations in the growth of the II-VI qua ntum well structures, which are responsible for the inhomogeneous line width, must also be made to a limit where the room temperature linewid th is narrow and homogeneously broadened.