Homogeneous linewidth broadening in a In_0.5Ga_0.5As/GaAs single quantum dot at room temperature investigated using a highly sensitive near-field scanning optical microscope

We have studied the spectral homogeneous broadening of self-assembled In_0.5Ga_0.5As single quantum dots in a high-temperature regime with a highly sensitive near-field scanning optical microscope. Through precise examination of the photoluminescence spectra under weak excitation conditions, the homogeneous linewidth of the quantum dot was estimated to be about 12 meV at 300 K. We also found that the homogeneous linewidth changes with the interlevel spacing energy. It is shown that these experimental results on the homogeneous linewidths are well explained by means of a theoretical model considering the electron-longitudinal optical phonon and electron-longitudinal acoustic phonon interactions.