Carrier–carrier interaction in single In0.5Ga0.5As quantum dots at room temperature investigated by near-field scanning optical microscope

We describe carrier–carrier interaction in self-assembled ${\mathrm{In}}_{\text{0.5}}{\mathrm{Ga}}_{\text{0.5}}\mathrm{As}$ quantum dots (QDs) at room temperature. The spectral shift and linewidth broadening of ground state emission as a function of the excitation density are investigated through near-field single quantum dot photoluminescence spectroscopy. From the viewpoint of excitation density dependent spectral broadening of the ground state emission, we discuss the dephasing process in QDs due to Coulomb interaction.