Temperature dependence of photoreflectance line shapes in [formula omitted] multiple quantum wells

Abstract

The temperature dependence of the photoreflectance (PR) line shape of the excitonic transitions in GaAs AlGaAs multiple quantum wells has been studied. At low temperatures, near 6K, we find that the PR lines can be described by a dielectric function of a Lorentzian oscillator. At higher temperatures, we have observed the evolution of the dielectric function from one with a Lorentzian absorption profile to one with a Gaussian absorption profile. The dielectric function of excitonic absorptions is expected to exhibit this behavior in cases of weak exciton-phonon coupling.