Quantum beat of strain-induced GaAs quantum dots

We report the observation of two kinds of quantum beats in the time-resolved photoluminescence of the strain-induced GaAs quantum dots in the magnetic field parallel and perpendicular to the growth direction. They come from the Zeeman splitting of bright excitons in the Faraday configuration and electron Larmor precession in the Voigt configuration. Analysis of the oscillation period depending on the magnetic field strength, its orientation and the polarizations of excitation and luminescent light gives g-factors of the exciton, the electron and the heavy hole depending on the crystal orientation. The electron g-factor obtained by the analysis of the quantum beat observed in the Faraday configuration agrees with that obtained directly from the electron Larmor precession in the Voigt configuration. The isotropic electron g-factor is observed in contrast to the anisotropic electron g-factor for the corresponding quantum well and is ascribed to the strain-induced opposite energy shift of heavy and light hole bands.