Resonant and non-resonant PL and PLE spectra ofCdSe/ZnSe and CdTe/ZnTe self-assembled quantumdots

摘要

Using micro- and nano-scale resonantly excited PL and PLE, westudy the excitonic structure of CdSe/ZnSe and CdTe/ZnTe self assembledquantum dots (SAQD). Strong resonantly enhanced PL is seen at one tofour optic phonon energies below the laser excitation energy. Themaximum enhancement is not just one phonon energy above the peakenergy distribution of QDs, but rather is 50 meV (for CdSe dots) or 100meV (for CdTe) above the peak distribution. We interpret this unusualresult as from double resonances associated with excited state to groundstate energies being commensurate with LO phonons. Such a situationappears to occur only for the high-energy quantum dots.