Luminescence linewidths of excitons in GaAs quantum wells below 150 K

We present detailed experimental studies and a theoretical model of the linewidth as a function of temperature (<150 K) for both heavy-hole and light-hole excitons in a GaAs-${\mathrm{Al}}_{\mathrm{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$As quantum well. The contributions to the linewidth of the exciton luminescence include interactions with polar optical phonons, with acoustic phonons (via deformation and piezoelectric potentials), with ionized impurities, and with fluctuations in the thickness of the well. We find that the linewidth increases sublinearly with temperature in the range 0 K to about 70 K but increases more sharply as the temperature is raised still higher.