Efficient spin depolarization in ZnCdSe spin detector: an important factor limiting optical spin injection efficiency in spin light-emitting structures
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(a) A typical PL and PLE spectrum of the ZnCdSe QW SD from the studied structures, taken at . The PLE spectrum was obtained by measuring the QW PL intensity as a function of excitation photon energy of the light in the cw optical orientation experiments. (b) PL polarization of the ZnCdSe SD as a function of the excitation photon energy of the light. The features related to the excitonic bandgaps of the DMS and the ZnSe spacer are indicated by the vertical lines.
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(a) Typical decay curves of the ZnCdSe QW PL under the excitation at the energies that are about six and seven times the LO phonon energy above the bottom of the hh exciton band, taken at . The decay can be satisfactorily described by a single exponent with a decay time of about , which is independent of the excitation photon energy. (b) The decay curves of the PL polarization under the excitation, exhibiting three distinct spin relaxation processes with the corresponding polarization decay times of 850, 30, and . Here, denotes the excitation photon energy of the light, and the energy of the hh exciton of the QW at . The fitting curves are also shown by including the contributions from the two depolarization components of 850 and that can be resolved within the experimental resolution.
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