Temperature Dependence of Interface-state-phonon Assisted Carrier Relaxation in CdSe Quantum Dots

摘要

In this work, time-resolved microscopic photoluminescence (PL) spectra of self-assembled CdSe quantum dots (QDs) grown by Molecular Beam Epitaxy were investigated under excitation of femto-second laser. Interface-state-phonon (ISP) assisted carrier relaxation in self-assembled CdSe quantum dots are investigated by ultrafast time-resolved photoluminescence (PL). Electrons excited in barriers are found to relax into quantum dots and then have radiative recombination with holes by the mean of ISP assisted relaxation. Temperature dependence of rise time and decay time of time-resolved PL spectra are measured in the temperature range from 77 K to 286 K. The rise time decreases from 76 ps to 32 ps while the decay time first decreases then increases accordingly. The rise time shows exponential decay with the increasing of temperature. The thermal activation temperature for ISP process is deduced to be 184.9 K, corresponding to a thermal activation energy of 16 meV.