Abstract

A variety of optoelectronic devices utilize the unique properties of excitons in quantum well structures. Exciton linewidths are important design parameters in optimizing performance of certain devices. We have investigated exciton linewidths in a series of high quality MBE GaAs/(Al,Ga)As superlattice samples. The well widths and the aluminum concentrations in the barrier layers were fixed while the barrier layer thicknesses were varied. The samples were designed to have low potential barrier heights and substantial subband dispersion. The superlattice layer widths were accurately determined by cross-sectional transmission electron microscopy. The exciton peak widths were measured by excitation spectroscopy performed at 15 K. We have found that both the heavy hole and light hole excitonic peak widths decrease as the barrier width decreases. Significant narrowing was observed between the thick barrier quantum well-like samples and thin barrier superlattices with substantial well couplings.

© 1989 Optical Society of America