Spin Phenomena of CdZnSe Self-assembled Quantum Dots Investigated by 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 tau(s) and the exciton recombination time tau(r), 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 tau(s)/tau(r), as a fitting parameter in the model. The best fitting was obtained with the value of tau(s)/tau(r) similar to sigma or, 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.