Spin Phenomena of CdZnSe Self-assembled Quantum Dots Investigatedby Magneto-photoluminescence

Abstract

Magneto-photoluminescence (PL) experiments were carried out on a self-assembled CdZnSe/ZnSe quantum dot (QD) system. The intensities of the PL peak exhibited significant differences for the two circular polarizations when a magnetic field was applied. A simple two-level rate equation model, including the spin flip time τs and the exciton recombination time τr , was used to analyze the observed degree of the polarization in the polarization selective PL measurements. Specifically, the magnetic field dependence of the polarization was fitted by treating τs/τr as a fitting parameter in the model. The best fitting was obtained with the value of τs/τr ∼ σ, indicating that the spin relaxation time is much longer than the exciton recombination time. Such polarization selective PL measurements were further performed at several different temperatures, which showed a systematic decrease in the degree of polarization with increasing temperature.