Temperature dependence of the exciton homogeneous linewidth in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">In</mml:mi></mml:mrow><mml:mrow><mml:mn>0.60</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Ga</mml:mi></mml:mrow><mml:mrow><mml:mn>0.40</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mi mathvariant="normal">As</mml:mi><mml:mo>/</mml:mo><mml:mi mathvariant="normal">GaAs</mml:mi></mml:math>self-assembled quantum dots

Single dot photoluminescence spectroscopy was used to study the homogeneous linewidth $\ensuremath{\Gamma}$ 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 \ensuremath{\Gamma} with temperature up to $\ensuremath{\sim}30 \ensuremath{\mu}\mathrm{eV}$ 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.