Spin dynamics and magnetic-field-induced polarization of excitons in ultrathin GaAs/AlAs quantum wells with indirect band gap and type-II band alignment

Abstract

The exciton spin dynamics are investigated both experimentally and theoretically in two-monolayer-thick GaAs/AlAs quantum wells with an indirect band gap and a type-II band alignment. The magnetic-field-induced circular polarization of photoluminescence, $P_c$, is studied as function of the magnetic field strength and direction as well as sample temperature. The observed nonmonotonic behaviour of these functions is provided by the interplay of bright and dark exciton states contributing to the emission. To interpret the experiment, we have developed a kinetic master equation model which accounts for the dynamics of the spin states in this exciton quartet, radiative and nonradiative recombination processes, and redistribution of excitons between these states as result of spin relaxation. The model offers quantitative agreement with experiment and allows us to evaluate, for the studied structure, the heavy-hole $g$ factor, $g_{hh}=+3.5$, and the spin relaxation times of electron, ${\tau }_{se}=33\mu$s, and hole, ${\tau }_{sh}=3\mu$s, bound in the exciton.

arXiv comment17 pages, 16 figures

References in corpus (9)

• Spin relaxation in semiconductor quantum dots
• Spin-flip transitions between Zeeman sublevels in semiconductor quantum dots
• Universal behavior of the electron g-factor in GaAs/AlGaAs quantum wells
• Spin-flip Raman scattering of the $\Gamma$-X mixed exciton in indirect band-gap (In,Al)As/AlAs quantum dots
• Longitudinal spin-relaxation of donor-bound electrons in direct bandgap semiconductors
• Electron and hole g factors in InAs/InAlGaAs self-assembled quantum dots emitting at telecom wavelengths
• Giant Zeeman splitting of light holes in GaAs/AlGaAs quantum wells
• Exciton spin dynamics of colloidal CdTe nanocrystals in magnetic field
• Zeeman splitting of light hole in quantum wells: comparison of theory and experiments

Cited by in corpus (3)

• Dynamic polarization of electron spins in indirect band gap (In,Al)As/AlAs quantum dots in weak magnetic field: experiment and theory
• Electron spin relaxation in X-valley of indirect bandgap AlxGa1-xAs: A new horizon for the realization of next generation spin-photonic devices
• The role of resident electrons in manifestation of a spin polarization memory effect in Mn delta-doped GaAs heterostructures