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Phonon Emission (phonon + emission)
Selected AbstractsTunneling current through g -factor engineered series quantum dotsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 4 2009Yasuhiro Tokura Abstract We evaluate resonant tunneling current via series quantum dots with different g -factors by Bloch equation method. We found that the resonant current is always singly peaked as a function of bias and its peak position depends on the gate voltage. When the rate of spontaneous phonon emission is very small, the shift of the peak positions between single spin transport and both spin transport corresponds to the half of the difference of the Zeeman energy. In contrast, when the phonon assisted tunneling predominates, the peak always appears at one of the resonant tunneling conditions for larger bias. These features are explained by spin blockade effect. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Interwell exciton dispersion engineering, coherent phonons generation and optical detection of exciton condensatePHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 1 2004Yu. E. Lozovik Abstract We propose to use dispersion engineering of interwell excitons in coupled quantum wells with external electric and magnetic fields in order to generate coherent phonons and to detect exciton condensate. A parallel magnetic field moves the dispersion minimum of interwell excitons away from the radiative zone and thus reduces their recombination rate. Normal electric field moves an interwell excitons dispersion minimum on the energy scale. These two fields effect can be used to tune the resonance condition of the interwell excitons recombination process via an in-well excitons level, which results in acoustic phonon emission. We show, that one can change recombination rate as well as intensity and angular distribution of the interwell excitons photoluminescence in the wide range by controlling the external fields. Based on this principle we propose and theoretically evaluate a procedure to detect the condensate of interwell excitons, as well as a scheme to obtain a coherent and monochromatic phonon beam (saser). The statistics of the phonon emission from the condensate of interwell excitons is studied. Numerical estimate for GaAs/AlGaAs coupled quantum wells is provided. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Is polaron effect important for resonant Raman scattering in self-assembled quantum dots?PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2005M. I. Vasilevskiy Abstract While the diagonal (or intra-level) interaction of a confined exciton with optical phonons in self-assembled quantum dots (SAQD's) is rather weak, the non-diagonal one can lead to a considerable change of the exciton spectrum and the formation of a polaron. An impact of this effect on resonant inelastic light scattering is studied theoretically. The polaron spectrum is obtained by numerical diagonalisation of the exciton,phonon interaction Hamiltonian in a truncated Hilbert space of the non-interacting excitons and phonons. Based on this spectrum, the probability of the multi-phonon Raman scattering is calculated, which is compared to that obtained within the standard perturbation theory approach (where phonon emission and absorption are irreversible). It is shown that there are two major effects of the polaron formation: (i) the intensity of the two-phonon (2 LO) peak, relative to that of the fundamental 1 LO one is strongly increased and (ii) the resonant behaviour of the 1 LO peak differs considerably from the perturbation theory predictions. With the correct theoretical interpretation, resonant Raman scattering in SAQD's opens the possibility of accessing the (renormalised) exciton spectrum and exciton,phonon coupling constants. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||