Study of high density excitation magneto-optical phenomena in semiconductor nano-structures

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In ZnSe or CdS/ZnSe type II quantum wells, high efficiency photoluminescence at the band-edge has been investigated systematically. Charged excitons and/or their high density states have been suggested as a possible origin for the strong luminescence., We have performed four-wave-mixing measurements in dilute magnetic semiconductor quantum wells, .which leads to observation of exciton-biexciton quantum beats. An anibonding biexciton has known to increase its oscillator strength on increasing magnetic field, resulted in a pronounced quantum beat. Time-resolved photoluminescence measurements revealed the importance of spin scattering by Mn localized spins for the non-equilibrium dynamical statistics of an exciton and a biexciton in the system. It has been found that a charged exciton transition in a quantum well, is induced by Mn intra-ionic photo-excitation in the dilute magnetic semiconductor barriers. In n-doped dilute magnetic semiconductor, quantum wells, dark and bright triplet cha … More rged exciton photoluminescence transitions have been clarified subjected to a strong magnetic field. Dynamical processes and optical properties of the exciton magnetic polarons .realized in bulk-dilute magnetic semiconductors have been understood. Self-trap type localization ,induced by; a spin exchange interaction has been elucidated in comparison to the theory. Femto-second pump-and-probe Faraday rotation has been applied to the same system, and photo-induced magnetic order has been confirmed. Magnetic polaron formation process has also been understood in relationship to the spin dynamics. The "renormalization" effect plays an important role in the spin dependent exciton interaction. It has been pointed out theoretically that the exciton-exciton interaction depends much on the relative direction of photon polarization and, a rnagnetic field. Theoretical analysis has been applied to a photonic crystal, which is a candidate for realizing a high-density excitation state. Spectral profile of the semi-super cell radiation resulted from a high-speed electron passing through dielectric spheres consisting of the crystal. Less