Abstract

At low excitation intensities the transmission and luminescence spectra of high quality direct gap semiconductor quantum wells are dominated by exciton transitions. The dynamics of these excitons is characterized by different relaxation times like the phase coherence time T₂ and the recombination lifetime τ. The recombination lifetime of such two-dimensional (2D) excitons as well as its variation with the quantum well thickness L₂ and the temperature T has been studied extensively by means of time-resolved photolumiaescence.¹ On the other hand much less information is available for the phase coherence time T₂ and the corresponding homogeneous linewidth Γ_h of these excitons because of the more complicated methods needed to measure it.² The phase coherence time T₂ is sensitive to all interactions of the excitons and, therefore, phase relaxation normally appears on a much shorter time scale than recombination.

© 1988 Optical Society of America