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A. M. Smirnov,
V. A. Oseptsova,
A. V. Platonov,
A. S. Gurevich,
V. P. Kochereshko,
A. S. Shkolnik,
V. P. Evtikhiev, V. V. Petrov,
Yu. K. Dolgikh,
Yu. P. Efimov,
S. A. Eliseev
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ABSTRACT: Anisotropy of the relaxation of electron spin in AlGaAs quantum wells with an asymmetric profile in the growth-axis direction
is studied by the technique of optical orientation. It is demonstrated that the difference between the Hanle curves for [110]
and [1$
\bar 1
$
\bar 1
0] orientations does originate from the spin-relaxation anisotropy rather than the electron g-factor anisotropy. Contributions to the Hanle curves both from free and localized electrons, characterized by different lifetimes,
are observed.
Semiconductors 05/2012; 43(7):901-905. · 0.63 Impact Factor
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R. V. Cherbunin,
M. S. Kuznetsova,
I. Ya. Gerlovin,
I. V. Ignatiev,
Yu. K. Dolgikh,
Yu. P. Efimov,
S. A. Eliseev, V. V. Petrov,
S. V. Poltavtsev,
A. V. Larionov,
A. I. Il’in
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ABSTRACT: The spin orientation dynamics in a GaAs quantum well with a laterally nonuniform electric potential generated by a mosaic
electrode deposited on the surface of the sample has been investigated using the photoinduced magneto-optical Kerr effect.
It has been found that the application of a negative potential higher than 1 V to the electrode leads to more than a hundredfold
increase in the spin polarization lifetime in the sample under study. It is concluded that so strong slowing down of the relaxation
is caused by a combined action of two effects, namely, the spatial separation of electron and hole, which reduces the radiative
recombination rate of electron-hole pair, and the localization of electron, which is accompanied by the suppression of spin
relaxation processes caused by electron motion.
Physics of the Solid State 04/2012; 51(4):837-840. · 0.71 Impact Factor
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ABSTRACT: The thickness of the GaAs “dead layer” in the GaAs/AlGaAs heterostructure has been directly measured. The widths of the dead
layer obtained in the experiment are compared with the values for the same material interfacing with the external medium which
were found earlier, as well as with theoretical predictions made by different authors.
Physics of the Solid State 04/2012; 51(9):1929-1934. · 0.71 Impact Factor
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ABSTRACT: The mechanisms of exciton coherence relaxation in GaAs quantum wells in the linear mode have been experimentally investigated.
An experimental technique has been developed for measuring the total phase relaxation rate, rates of reversible and temperature-irreversible
excitonic phase relaxation, and the radiative decay rate Γ
R
of excitonic polarization. The experimental values of Γ
R
for a quantum well of specified thickness, obtained for a series of samples, have a spread not larger than 15%. This accuracy
made it possible to estimate the shape of the dependence of Γ
R
on the well thickness L
Z
. It is experimentally found that Γ
R
is temperature-independent up to 80 K.
Optics and Spectroscopy 09/2008; 105(4):511-516. · 0.61 Impact Factor
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ABSTRACT: The optical reflection spectra of semiconductor GaAs/AlGaAs structures with wide quantum wells are studied experimentally.
A theoretical analysis of the spectra is performed in terms of the exciton-polariton model in the approximation of quantum
confinement of the exciton center of mass with regard to the contributions of both heavy and light excitons to the crystal
polarization. The applicability range of the theory of the center-of-mass confinement for GaAs/AlGaAs heterostructures is
estimated. It is established that, for quantum wells more than 180 nm wide, the interference effects observed in the reflection
spectra of polariton waves are reproduced, to a good accuracy, by theoretical calculations based on the quantum confinement
of the exciton center of mass. For quantum-well widths less than 150 nm, the experimental results are described better by
the model of quantum confinement of electrons and holes.
Physics of the Solid State 10/2006; 48(11):2100-2108. · 0.71 Impact Factor
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ABSTRACT: A simple device for image scanning and storage based on a semiconductor structure is proposed. The scanning and storage involve
laser-beam reading. A video signal is represented by the photoelectromotive force generated by the structure. Simple experiments
demonstrating that the structure proposed works as a vidicon and a storage device capable of the data storage for at least
two hours are presented. A physical interpretation of the effects observed is proposed.
Technical Physics 05/2004; 49(6):728-732. · 0.50 Impact Factor
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ABSTRACT: Picosecond kinetics of polarized resonant photoluminescence (PL) of HH excitons in the GaAs/AlGaAs superlattices is studied in an external magnetic field. The measurements were made in real time using a streak camera. For the magnetic field aligned along the heterostructure growth direction, the resonant PL exhibits oscillations in the degree of linear polarization. The oscillations are ascribed to quantum beats between sublevels of the optically active excitonic doublet split by the magnetic field. For the magnetic field aligned along the plane of the layers, the resonant PL is found to exhibit oscillations in circular polarization. These oscillations are related to beats between states of the optically active and optically inactive excitonic doublets. Experimental dependence of the oscillation frequency on the magnetic field strength and orientation has allowed us to determine the hole and electron g factors and the electron-hole exchange energy. Dynamics of the degree of circular polarization of the PL in magnetic field is used to measure the energy relaxation rate of the exciton spin states. In the magnetic field exceeding 1 T, the energy relaxation rate is shown to be magnetic-field independent and equal (1±0.2)×1010 s-1. This value is found to be much smaller than the spin phase relaxation rate determined from decay of the quantum beats in linear polarization. Unlike the energy relaxation rate, the latter grows linearly with the field strength and equals (5±0.5)×1010 s-1 at 5 T. It is concluded that the main mechanism responsible for loss of macroscopic spin coherence is the reversible dephasing within inhomogeneously broadened system.
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ABSTRACT: The effect of external electric bias on the kinetics of circularly polarized photoluminescence (PL) of the GaAs quantum wells (QWs) is studied experimentally. It is found that a negative bias applied to the top surface of the samples causes the appearance of a slow component in the decay of the PL circular polarization. The amplitude of this component grows with the bias Ubias and reaches nearly 100% at Ubias=-2 V. In a transverse magnetic field, the polarization decay shows oscillations related to the spin precession. The changes in the shape of the oscillations with the applied bias indicate a transition from the exciton spin precession to that of the electron spin. Based on the analysis of the experimental data, we came to the conclusion that the external electric field reduces the exchange coupling between the electron and hole spins. As a result, the hole spin exhibits fast relaxation whereas the electron spin holds its light-induced orientation for a relatively long time. The studies of the electron spin dynamics in oblique magnetic fields have allowed us to estimate the effective energy of the electron–hole exchange interaction in the electric field created by the bias Ubias=-2 V. The exchange splitting thus obtained is much smaller than typical exchange splittings of the excitonic states in the GaAs QWs.
