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T S Shamirzaev - One of the best experts on this subject based on the ideXlab platform.

  • Optical orientation and alignment of excitons in direct and Indirect Band Gap (In,Al)As/AlAs quantum dots with type-I Band alignment
    Physical Review B, 2019
    Co-Authors: J. Rautert, T S Shamirzaev, D R Yakovlev, S. V. Nekrasov, Petr Klenovský, Yu. G. Kusrayev, Manfred Bayer
    Abstract:

    The spin structure and spin dynamics of excitons in an ensemble of (In,Al)As/AlAs quantum dots (QDs) with type-I Band alignment, containing both direct and Indirect Band Gap dots, are studied. Time-resolved and spectral selective techniques are used to distinguish between the direct and Indirect QDs. The exciton fine structure is studied by means of optical alignment and optical orientation techniques in magnetic fields applied in the Faraday or Voigt geometries. A drastic difference in emission polarization is found for the excitons in the direct QDs involving a $\Gamma$-valley electron and the excitons in the Indirect QDs contributed by an $X$-valley electron. We show that in the direct QDs the exciton spin dynamics is controlled by the anisotropic exchange splitting, while in the Indirect QDs it is determined by the hyperfine interaction with nuclear field fluctuations. The anisotropic exchange splitting is determined for the direct QD excitons and compared with model calculations.

  • optical orientation and alignment of excitons in direct and Indirect Band Gap in al as alas quantum dots with type i Band alignment
    Physical Review B, 2019
    Co-Authors: J. Rautert, T S Shamirzaev, D R Yakovlev, S. V. Nekrasov, Petr Klenovský, Yu. G. Kusrayev, M Bayer
    Abstract:

    The spin structure and spin dynamics of excitons in an ensemble of (In,Al)As/AlAs quantum dots (QDs) with type-I Band alignment, containing both direct and Indirect Band Gap dots, are studied. Time-resolved and spectral selective techniques are used to distinguish between the direct and Indirect QDs. The exciton fine structure is studied by means of optical alignment and optical orientation techniques in magnetic fields applied in the Faraday or Voigt geometries. A drastic difference in emission polarization is found for the excitons in the direct QDs involving a $\mathrm{\ensuremath{\Gamma}}$-valley electron and the excitons in the Indirect QDs contributed by an $X$-valley electron. We show that in the direct QDs the exciton spin dynamics is controlled by the anisotropic exchange splitting, while in the Indirect QDs it is determined by the hyperfine interaction with nuclear field fluctuations. The anisotropic exchange splitting is determined for the direct QD excitons and compared with model calculations.

  • spin dynamics and magnetic field induced polarization of excitons in ultrathin gaas alas quantum wells with Indirect Band Gap and type ii Band alignment
    Physical Review B, 2017
    Co-Authors: T S Shamirzaev, J Debus, D R Yakovlev, M M Glazov, E L Ivchenko, J. Rautert, Yu A Gornov, M Bayer
    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.

  • Spin dynamics and magnetic field induced polarization of excitons in ultrathin GaAs/AlAs quantum wells with Indirect Band Gap and type-II Band alignment
    Physical Review B, 2017
    Co-Authors: T S Shamirzaev, J Debus, D R Yakovlev, M M Glazov, E L Ivchenko, J. Rautert, A. Yu. Gornov, Manfred Bayer
    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.

  • dynamics of exciton recombination in strong magnetic fields in ultrathin gaas alas quantum wells with Indirect Band Gap and type ii Band alignment
    Physical Review B, 2016
    Co-Authors: T S Shamirzaev, J Debus, D R Yakovlev, M M Glazov, E L Ivchenko, M Bayer
    Abstract:

    The exciton recombination dynamics is studied experimentally and theoretically in two-monolayer-thick GaAs/AlAs quantum wells characterized by an Indirect Band Gap and a type-II Band alignment. At cryogenic temperatures, the lifetimes of the excitons that are Indirect both in real and $\mathbit{k}$ space are in the millisecond range. The exciton recombination time and the photoluminescence (PL) intensity are strongly dependent on strength and orientation of an applied magnetic field. In contrast to the very weak influence of an in-plane field, at 2 K temperature a field applied parallel to the growth axis drastically slows down the recombination and reduces the PL intensity. With increasing temperature the magnetic field effects on PL intensity and decay time are vanishing. The experimental data are well described by a model for the exciton dynamics that takes into account the magnetic-field-induced redistribution of the Indirect excitons between their bright and dark states. It allows us to evaluate the lower bound of the heavy-hole longitudinal $g$ factor of 2.5, the radiative recombination time for the bright excitons of 0.34 ms, and the nonradiative recombination time of the bright and dark excitons of 8.5 ms.

M Bayer - One of the best experts on this subject based on the ideXlab platform.

  • optical orientation and alignment of excitons in direct and Indirect Band Gap in al as alas quantum dots with type i Band alignment
    Physical Review B, 2019
    Co-Authors: J. Rautert, T S Shamirzaev, D R Yakovlev, S. V. Nekrasov, Petr Klenovský, Yu. G. Kusrayev, M Bayer
    Abstract:

    The spin structure and spin dynamics of excitons in an ensemble of (In,Al)As/AlAs quantum dots (QDs) with type-I Band alignment, containing both direct and Indirect Band Gap dots, are studied. Time-resolved and spectral selective techniques are used to distinguish between the direct and Indirect QDs. The exciton fine structure is studied by means of optical alignment and optical orientation techniques in magnetic fields applied in the Faraday or Voigt geometries. A drastic difference in emission polarization is found for the excitons in the direct QDs involving a $\mathrm{\ensuremath{\Gamma}}$-valley electron and the excitons in the Indirect QDs contributed by an $X$-valley electron. We show that in the direct QDs the exciton spin dynamics is controlled by the anisotropic exchange splitting, while in the Indirect QDs it is determined by the hyperfine interaction with nuclear field fluctuations. The anisotropic exchange splitting is determined for the direct QD excitons and compared with model calculations.

  • spin dynamics and magnetic field induced polarization of excitons in ultrathin gaas alas quantum wells with Indirect Band Gap and type ii Band alignment
    Physical Review B, 2017
    Co-Authors: T S Shamirzaev, J Debus, D R Yakovlev, M M Glazov, E L Ivchenko, J. Rautert, Yu A Gornov, M Bayer
    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.

  • dynamics of exciton recombination in strong magnetic fields in ultrathin gaas alas quantum wells with Indirect Band Gap and type ii Band alignment
    Physical Review B, 2016
    Co-Authors: T S Shamirzaev, J Debus, D R Yakovlev, M M Glazov, E L Ivchenko, M Bayer
    Abstract:

    The exciton recombination dynamics is studied experimentally and theoretically in two-monolayer-thick GaAs/AlAs quantum wells characterized by an Indirect Band Gap and a type-II Band alignment. At cryogenic temperatures, the lifetimes of the excitons that are Indirect both in real and $\mathbit{k}$ space are in the millisecond range. The exciton recombination time and the photoluminescence (PL) intensity are strongly dependent on strength and orientation of an applied magnetic field. In contrast to the very weak influence of an in-plane field, at 2 K temperature a field applied parallel to the growth axis drastically slows down the recombination and reduces the PL intensity. With increasing temperature the magnetic field effects on PL intensity and decay time are vanishing. The experimental data are well described by a model for the exciton dynamics that takes into account the magnetic-field-induced redistribution of the Indirect excitons between their bright and dark states. It allows us to evaluate the lower bound of the heavy-hole longitudinal $g$ factor of 2.5, the radiative recombination time for the bright excitons of 0.34 ms, and the nonradiative recombination time of the bright and dark excitons of 8.5 ms.

  • exciton recombination dynamics in an ensemble of in al as alas quantum dots with Indirect Band Gap and type i Band alignment
    Physical Review B, 2011
    Co-Authors: T S Shamirzaev, J Debus, D R Yakovlev, D. Dunker, K. S. Zhuravlev, D S Abramkin, D V Dmitriev, A K Gutakovskii, L S Braginsky, M Bayer
    Abstract:

    The dynamics of exciton recombination in an ensemble of Indirect Band-Gap (In,Al)As/AlAs quantum dots with type-I Band alignment is studied. The lifetime of confined excitons that are Indirect in momentum space is mainly influenced by the sharpness of the heterointerface between the (In,Al)As quantum dot and the AlAs barrier matrix. Time-resolved photoluminescence experiments and theoretical model calculations reveal a strong dependence of the exciton lifetime on the thickness of the interface diffusion layer. The lifetime of excitons with a particular optical transition energy varies because this energy is obtained for quantum dots differing in size, shape, and composition. The different exciton lifetimes, which result in photoluminescence with nonexponential decay obeying a power-law function, can be described by a phenomenological distribution function G(τ), which allows one to fit the photoluminescence decay with one parameter only.

D R Yakovlev - One of the best experts on this subject based on the ideXlab platform.

  • Optical orientation and alignment of excitons in direct and Indirect Band Gap (In,Al)As/AlAs quantum dots with type-I Band alignment
    Physical Review B, 2019
    Co-Authors: J. Rautert, T S Shamirzaev, D R Yakovlev, S. V. Nekrasov, Petr Klenovský, Yu. G. Kusrayev, Manfred Bayer
    Abstract:

    The spin structure and spin dynamics of excitons in an ensemble of (In,Al)As/AlAs quantum dots (QDs) with type-I Band alignment, containing both direct and Indirect Band Gap dots, are studied. Time-resolved and spectral selective techniques are used to distinguish between the direct and Indirect QDs. The exciton fine structure is studied by means of optical alignment and optical orientation techniques in magnetic fields applied in the Faraday or Voigt geometries. A drastic difference in emission polarization is found for the excitons in the direct QDs involving a $\Gamma$-valley electron and the excitons in the Indirect QDs contributed by an $X$-valley electron. We show that in the direct QDs the exciton spin dynamics is controlled by the anisotropic exchange splitting, while in the Indirect QDs it is determined by the hyperfine interaction with nuclear field fluctuations. The anisotropic exchange splitting is determined for the direct QD excitons and compared with model calculations.

  • optical orientation and alignment of excitons in direct and Indirect Band Gap in al as alas quantum dots with type i Band alignment
    Physical Review B, 2019
    Co-Authors: J. Rautert, T S Shamirzaev, D R Yakovlev, S. V. Nekrasov, Petr Klenovský, Yu. G. Kusrayev, M Bayer
    Abstract:

    The spin structure and spin dynamics of excitons in an ensemble of (In,Al)As/AlAs quantum dots (QDs) with type-I Band alignment, containing both direct and Indirect Band Gap dots, are studied. Time-resolved and spectral selective techniques are used to distinguish between the direct and Indirect QDs. The exciton fine structure is studied by means of optical alignment and optical orientation techniques in magnetic fields applied in the Faraday or Voigt geometries. A drastic difference in emission polarization is found for the excitons in the direct QDs involving a $\mathrm{\ensuremath{\Gamma}}$-valley electron and the excitons in the Indirect QDs contributed by an $X$-valley electron. We show that in the direct QDs the exciton spin dynamics is controlled by the anisotropic exchange splitting, while in the Indirect QDs it is determined by the hyperfine interaction with nuclear field fluctuations. The anisotropic exchange splitting is determined for the direct QD excitons and compared with model calculations.

  • spin dynamics and magnetic field induced polarization of excitons in ultrathin gaas alas quantum wells with Indirect Band Gap and type ii Band alignment
    Physical Review B, 2017
    Co-Authors: T S Shamirzaev, J Debus, D R Yakovlev, M M Glazov, E L Ivchenko, J. Rautert, Yu A Gornov, M Bayer
    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.

  • Spin dynamics and magnetic field induced polarization of excitons in ultrathin GaAs/AlAs quantum wells with Indirect Band Gap and type-II Band alignment
    Physical Review B, 2017
    Co-Authors: T S Shamirzaev, J Debus, D R Yakovlev, M M Glazov, E L Ivchenko, J. Rautert, A. Yu. Gornov, Manfred Bayer
    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.

  • dynamics of exciton recombination in strong magnetic fields in ultrathin gaas alas quantum wells with Indirect Band Gap and type ii Band alignment
    Physical Review B, 2016
    Co-Authors: T S Shamirzaev, J Debus, D R Yakovlev, M M Glazov, E L Ivchenko, M Bayer
    Abstract:

    The exciton recombination dynamics is studied experimentally and theoretically in two-monolayer-thick GaAs/AlAs quantum wells characterized by an Indirect Band Gap and a type-II Band alignment. At cryogenic temperatures, the lifetimes of the excitons that are Indirect both in real and $\mathbit{k}$ space are in the millisecond range. The exciton recombination time and the photoluminescence (PL) intensity are strongly dependent on strength and orientation of an applied magnetic field. In contrast to the very weak influence of an in-plane field, at 2 K temperature a field applied parallel to the growth axis drastically slows down the recombination and reduces the PL intensity. With increasing temperature the magnetic field effects on PL intensity and decay time are vanishing. The experimental data are well described by a model for the exciton dynamics that takes into account the magnetic-field-induced redistribution of the Indirect excitons between their bright and dark states. It allows us to evaluate the lower bound of the heavy-hole longitudinal $g$ factor of 2.5, the radiative recombination time for the bright excitons of 0.34 ms, and the nonradiative recombination time of the bright and dark excitons of 8.5 ms.

Manfred Bayer - One of the best experts on this subject based on the ideXlab platform.

  • Optical orientation and alignment of excitons in direct and Indirect Band Gap (In,Al)As/AlAs quantum dots with type-I Band alignment
    Physical Review B, 2019
    Co-Authors: J. Rautert, T S Shamirzaev, D R Yakovlev, S. V. Nekrasov, Petr Klenovský, Yu. G. Kusrayev, Manfred Bayer
    Abstract:

    The spin structure and spin dynamics of excitons in an ensemble of (In,Al)As/AlAs quantum dots (QDs) with type-I Band alignment, containing both direct and Indirect Band Gap dots, are studied. Time-resolved and spectral selective techniques are used to distinguish between the direct and Indirect QDs. The exciton fine structure is studied by means of optical alignment and optical orientation techniques in magnetic fields applied in the Faraday or Voigt geometries. A drastic difference in emission polarization is found for the excitons in the direct QDs involving a $\Gamma$-valley electron and the excitons in the Indirect QDs contributed by an $X$-valley electron. We show that in the direct QDs the exciton spin dynamics is controlled by the anisotropic exchange splitting, while in the Indirect QDs it is determined by the hyperfine interaction with nuclear field fluctuations. The anisotropic exchange splitting is determined for the direct QD excitons and compared with model calculations.

  • Spin dynamics and magnetic field induced polarization of excitons in ultrathin GaAs/AlAs quantum wells with Indirect Band Gap and type-II Band alignment
    Physical Review B, 2017
    Co-Authors: T S Shamirzaev, J Debus, D R Yakovlev, M M Glazov, E L Ivchenko, J. Rautert, A. Yu. Gornov, Manfred Bayer
    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.

  • Dynamics of exciton recombination in strong magnetic fields in ultrathin GaAs/AlAs quantum wells with Indirect Band Gap and type-II Band alignment
    Physical Review B, 2016
    Co-Authors: T S Shamirzaev, J Debus, D R Yakovlev, M M Glazov, E L Ivchenko, Manfred Bayer
    Abstract:

    The exciton recombination dynamics is studied experimentally and theoretically in two-monolayer-thick GaAs/AlAs quantum wells characterized by an Indirect Band Gap and a type-II Band alignment. At cryogenic temperatures, the lifetimes of the excitons that are Indirect both in real and $\mathbit{k}$ space are in the millisecond range. The exciton recombination time and the photoluminescence (PL) intensity are strongly dependent on strength and orientation of an applied magnetic field. In contrast to the very weak influence of an in-plane field, at 2 K temperature a field applied parallel to the growth axis drastically slows down the recombination and reduces the PL intensity. With increasing temperature the magnetic field effects on PL intensity and decay time are vanishing. The experimental data are well described by a model for the exciton dynamics that takes into account the magnetic-field-induced redistribution of the Indirect excitons between their bright and dark states. It allows us to evaluate the lower bound of the heavy-hole longitudinal $g$ factor of 2.5, the radiative recombination time for the bright excitons of 0.34 ms, and the nonradiative recombination time of the bright and dark excitons of 8.5 ms.

  • Spin relaxation of negatively charged excitons in (In,Al)As/AlAs quantum dots with Indirect Band Gap and type-I Band alignment
    Applied Physics Letters, 2012
    Co-Authors: D. Dunker, T S Shamirzaev, J Debus, D R Yakovlev, K. S. Zhuravlev, Manfred Bayer
    Abstract:

    Spin dynamics of negatively charged excitons is experimentally studied in (In,Al)As/AlAs quantum dots with Indirect Band Gap and type-I Band alignment. At low temperatures of 1.8 K, the spin relaxation time is 55 μs in a magnetic field of 3 T. It decreases with increasing magnetic field as B−5, which evidences that the spin relaxation of the negatively charged excitons is provided by an one-acoustic-phonon process.

J Debus - One of the best experts on this subject based on the ideXlab platform.

  • spin dynamics and magnetic field induced polarization of excitons in ultrathin gaas alas quantum wells with Indirect Band Gap and type ii Band alignment
    Physical Review B, 2017
    Co-Authors: T S Shamirzaev, J Debus, D R Yakovlev, M M Glazov, E L Ivchenko, J. Rautert, Yu A Gornov, M Bayer
    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.

  • Spin dynamics and magnetic field induced polarization of excitons in ultrathin GaAs/AlAs quantum wells with Indirect Band Gap and type-II Band alignment
    Physical Review B, 2017
    Co-Authors: T S Shamirzaev, J Debus, D R Yakovlev, M M Glazov, E L Ivchenko, J. Rautert, A. Yu. Gornov, Manfred Bayer
    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.

  • dynamics of exciton recombination in strong magnetic fields in ultrathin gaas alas quantum wells with Indirect Band Gap and type ii Band alignment
    Physical Review B, 2016
    Co-Authors: T S Shamirzaev, J Debus, D R Yakovlev, M M Glazov, E L Ivchenko, M Bayer
    Abstract:

    The exciton recombination dynamics is studied experimentally and theoretically in two-monolayer-thick GaAs/AlAs quantum wells characterized by an Indirect Band Gap and a type-II Band alignment. At cryogenic temperatures, the lifetimes of the excitons that are Indirect both in real and $\mathbit{k}$ space are in the millisecond range. The exciton recombination time and the photoluminescence (PL) intensity are strongly dependent on strength and orientation of an applied magnetic field. In contrast to the very weak influence of an in-plane field, at 2 K temperature a field applied parallel to the growth axis drastically slows down the recombination and reduces the PL intensity. With increasing temperature the magnetic field effects on PL intensity and decay time are vanishing. The experimental data are well described by a model for the exciton dynamics that takes into account the magnetic-field-induced redistribution of the Indirect excitons between their bright and dark states. It allows us to evaluate the lower bound of the heavy-hole longitudinal $g$ factor of 2.5, the radiative recombination time for the bright excitons of 0.34 ms, and the nonradiative recombination time of the bright and dark excitons of 8.5 ms.

  • Dynamics of exciton recombination in strong magnetic fields in ultrathin GaAs/AlAs quantum wells with Indirect Band Gap and type-II Band alignment
    Physical Review B, 2016
    Co-Authors: T S Shamirzaev, J Debus, D R Yakovlev, M M Glazov, E L Ivchenko, Manfred Bayer
    Abstract:

    The exciton recombination dynamics is studied experimentally and theoretically in two-monolayer-thick GaAs/AlAs quantum wells characterized by an Indirect Band Gap and a type-II Band alignment. At cryogenic temperatures, the lifetimes of the excitons that are Indirect both in real and $\mathbit{k}$ space are in the millisecond range. The exciton recombination time and the photoluminescence (PL) intensity are strongly dependent on strength and orientation of an applied magnetic field. In contrast to the very weak influence of an in-plane field, at 2 K temperature a field applied parallel to the growth axis drastically slows down the recombination and reduces the PL intensity. With increasing temperature the magnetic field effects on PL intensity and decay time are vanishing. The experimental data are well described by a model for the exciton dynamics that takes into account the magnetic-field-induced redistribution of the Indirect excitons between their bright and dark states. It allows us to evaluate the lower bound of the heavy-hole longitudinal $g$ factor of 2.5, the radiative recombination time for the bright excitons of 0.34 ms, and the nonradiative recombination time of the bright and dark excitons of 8.5 ms.

  • Spin relaxation of negatively charged excitons in (In,Al)As/AlAs quantum dots with Indirect Band Gap and type-I Band alignment
    Applied Physics Letters, 2012
    Co-Authors: D. Dunker, T S Shamirzaev, J Debus, D R Yakovlev, K. S. Zhuravlev, Manfred Bayer
    Abstract:

    Spin dynamics of negatively charged excitons is experimentally studied in (In,Al)As/AlAs quantum dots with Indirect Band Gap and type-I Band alignment. At low temperatures of 1.8 K, the spin relaxation time is 55 μs in a magnetic field of 3 T. It decreases with increasing magnetic field as B−5, which evidences that the spin relaxation of the negatively charged excitons is provided by an one-acoustic-phonon process.