Unusual temperature-dependent optical properties of self-organized InAs/GaAs quantum dots at high excitation power

The temperature-dependent photoluminescence (PL) properties of InAs/GaAs se lf-organized quantum dots (QDs) have been investigated at high excitation p ower. The fast redshift of the ground-state and the first excited-state PL energy with increasing temperature was observed. The temperature-dependent linewidth of the QD ground state with high carrier density is different fro m that with low carrier density. Furthermore, we observed an increasing PL intensity of the first excited state of QDs with respect to that of the gro und state and demonstrate a local equilibrium distribution of carriers betw een the ground state and the first excited state for the QD ensemble at hig h temperature (T > 80 K). These results provide evidence for the slowdown o f carrier relaxation from the first excited state to the ground state in In As/GaAs quantum dots.