Abstract

There is currently a great deal of interest in exciton states in semiconductor superlattice materials. Since these studies are driven primarily by possible applications in laser diode technology, this work has been restricted to direct band gap crystalline semiconductors, where large radiative matrix elements support laser action. It is likely, however, that materials with weaker radiative transitions provide a different, but equally interesting arena for study. Longer-lived excitons undergo more complete thermalization allowing studies of relaxation processes and ground state interactions. For example, in bulk materials it is in indirect band gap semi­conductors where the condensation of electron-hole droplets has provided extensive information on exciton-exciton interactions. In this paper we shall discuss recent experiments in which we use time-resolved spectroscopy to probe the dynamics of exciton states in superlattice materials with long exciton lifetimes.

© 1984 Optical Society of America