Temperature dependence of the exciton homogeneous linewidth inIn0.60Ga0.40As/GaAsself-assembled quantum dots

Abstract

Single dot photoluminescence spectroscopy was used to study the homogeneous linewidth $\Gamma$ of the ground-state exciton in ${\mathrm{In}}_{0.60}{\mathrm{Ga}}_{0.40}\mathrm{As}/\mathrm{GaAs}$ quantum dots as function of temperature T. In high resolution experiments at 2 K, we find a linewidth that is limited by the excitonic lifetime corresponding to a dephasing time of almost a ns. The approximately linear increase of Γ with temperature up to $\sim 30\hspace{0.5em}\mu \mathrm{eV}$ at 60 K is considerably weaker than in structures of higher dimensionality. For higher T we observe a strong enhancement of the linewidth reaching eventually a few meV at room temperature that depends on the confined electronic shell structure.