S. A. Eliseev

Increasing of AlGaAs/GaAs quantum well robustness to resonant excitation by lowering Al concentration in barriers

The robustness of AlGaAs/GaAs quantum well to strong resonant excitation is studied. It was found that lowering Al concentration in barriers to 3% does not influence the measured radiative linewidth of exciton resonance in the sample at low intensities. At the same time parasitic broadening of the resonance by an additional resonant illumination is strongly suppressed as compared to the quantum well with 30% of Al in barriers.

Enhancement of the longitudinal magnetic moment of the exciton due to its motion

A new physical phenomenon has been found, namely a giant enhancement of the exciton magnetic moment due to its motion. This phenomenon was observed in GaAs, CdTe and ZnSe based quantum wells with QW widths much larger than the exciton Bohr radius. Consequently, it is relevant to any crystal with zinc blende structure.

Multiple-frequency quantum beats of quantum confined exciton states

A. V. Trifonov,1 I. Ya. Gerlovin,1 I. V. Ignatiev,1 I. A. Yugova,1 R. V. Cherbunin,1 Yu. P. Efimov,2 S. A. Eliseev,2 V. V. Petrov,2 and A. V. Kavokin1, 3 Spin Optics Laboratory, Saint Petersburg State University, 198504 St. Petersburg, Russia SPbU Resource Center “Nanophotonics”, Saint Petersburg State University, 198504 St. Petersburg, Russia Physics and Astronomy School, University of Southampton, Highfield, Southampton, SO171BJ, UK (Dated: July 16, 2015)

Microscopic modeling of exciton spectra in asymmetric quantum wells

A theoretical model of reflectance spectra is applied to the analysis of spectra of the two high-quality structures with asymmetric InGaAs/GaAs quantum wells. The analysis allows to quantitatively describe the exciton resonances related to the lowest quantum-confined exciton states. Main parameters of the quantum well potential profiles are obtained in the modeling.

Inversion of Zeeman splitting of exciton states in InGaAs quantum wells

Zeeman splitting of quantum-confined states of excitons in InGaAs quantum wells (QWs) is experimentally found to depend strongly on quantization energy. Moreover, it changes sign when the quantization energy increases with a decrease in the QW width. In the 87-nm QW, the sign change is observed for the excited quantum-confined states, which are above the ground state only by a few meV. A two-step approach for the numerical solution of the two-particle Schroedinger equation, taking into account the Coulomb interaction and valence-band coupling, is used for a theoretical justification of the observed phenomenon. The calculated variation of the g-factor convincingly follows the dependencies obtained in the experiments.

Decrease of heavy-hole exciton mass induced by uniaxial stress in GaAs/AlGaAs quantum well

D. K. Loginov, P. S. Grigoryev, E. V. Ubiyvovk, Yu. P. Efimov, S. A. Eliseev, V. A. Lovtcius, Yu. P. Petrov, and I. V. Ignatiev Spin Optics Laboratory, St. Petersburg State University, 198504 St. Petersburg, Russia Department of Physics, St. Petersburg State University, 198504 St. Petersburg, Russia Resource Center “Nanophotonics”, St. Petersburg State University, 198504 St. Petersburg, Russia (Dated: May 11, 2015)

Optical vidicon based on a layered semiconductor structure: Image reading and storage

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.

Spin memory in the n-doped GaAs/AlGaAs quantum wells

The polarized luminescence spectra and kinetics of the GaAs quantum wells with excess free electrons are studied experimentally. Quantum beats between the exciton and electron spin sublevels, split by a magnetic field, are detected. The dynamics of the degree of polarization is found to contain a long component associated with slow relaxation of electron spins.