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Yoichi Yamada - One of the best experts on this subject based on the ideXlab platform.
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Confinement-enhanced Biexciton binding energy in AlGaN-based quantum wells
Applied Physics Express, 2017Co-Authors: Katsuto Nakamura, Tomonori Fukuno, Hideto Miyake, Kazumasa Hiramatsu, Yoichi YamadaAbstract:The effect of quantum confinement on Biexcitons in Al0.60Ga0.40N/Al y Ga1− y N multiple quantum well (MQW) structures (0.60 < y) was studied. The Biexciton binding energy (B M) was evaluated by photoluminescence excitation spectroscopy as a function of well width (L W) and aluminum composition in the barrier layers (y). For MQWs with L W = 1.2 nm, B M increased from 112 to 162 meV as y increased from 0.70 to 0.74. In addition, for MQWs with L W = 1.5 nm, B M increased from 146 to 174 meV as y increased from 0.70 to 0.84. These increases resulted from higher quantum confinement of the Biexcitons.
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Binding energy of localized Biexcitons in AlGaN-based quantum wells
Applied Physics Express, 2014Co-Authors: Yuya Hayakawa, Tomonori Fukuno, Katsuto Nakamura, Hideto Miyake, Kazumasa Hiramatsu, Yoichi YamadaAbstract:The excitonic optical properties of Al0.60Ga0.40N/Al0.70Ga0.30N multiple quantum wells were studied by photoluminescence (PL) and PL excitation spectroscopies at room temperature. The binding energy of localized Biexcitons in quantum wells was evaluated to be 136 meV on the basis of the energy separation between the exciton resonance and the two-photon Biexciton resonance. This value was 2.4 times larger than the Biexciton binding energy of 56 meV in an Al0.61Ga0.39N ternary alloy epitaxial layer with almost the same aluminum composition as the quantum-well layers. This increase unambiguously resulted from the effect of quantum confinement on Biexcitons.
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Bowing of Biexciton binding in Al x Ga 1-x N ternary alloys
Gallium Nitride Materials and Devices VI, 2011Co-Authors: Yoichi YamadaAbstract:Biexciton binding in Al x Ga 1-x N ternary alloys as a function of alloy composition is reviewed on the basis of our recent experimental observations. The Biexciton binding energy in GaN and AlN was evaluated to be 5.6 and 19.3 meV, respectively. The Biexciton binding energy in Ga-rich Al x Ga 1-x N ternary alloys (x=0.019~0.092) and Al-rich Al x Ga 1-x N ternary alloys (x=0.81 and 0.89) was also evaluated on the basis of two-photon absorption of Biexcitons. The Biexciton binding energy in Ga-rich ternary alloys increased linearly with aluminum composition and reached to 16.6 meV for x=0.092. This value was three times as large as the Biexciton binding energy in GaN. Similarly, the Biexciton binding energy in Al-rich ternary alloys increased with decreasing aluminum composition and reached to 56 meV for x=0.81. A strong enhancement of the Biexciton binding was observed for both Ga-rich and Al-rich ternary alloys. The enhancement was attributed to the effect of localization due to alloy disorder. The results indicated that a linear interpolation between GaN and AlN did not apply to the Biexciton binding energy in the ternary alloys. A large bowing existed in the Biexciton binding energy in the ternary alloys.
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Recombination dynamics of localized Biexcitons in AlGaN ternary alloys (Invited Paper)
Ultrafast Phenomena in Semiconductors and Nanostructure Materials IX, 2005Co-Authors: Yoichi YamadaAbstract:Excitonic optical properties of Ga-rich Al x Ga 1-x N ternary alloy epitaxial layers are reviewed on the basis of our recent experimental observations. Photoluminescence due to radiative recombination of Biexcitons was clearly observed from the ternary alloys with different aluminum compositions (x=0.019 ~ 0.15). Recombination dynamics of excitons and Biexcitons was studied by means of time-resolved photoluminescence spectroscopy. The effect of localization due to alloy disorder on Biexcitons was also studied by means of photoluminescence excitation spectroscopy. A Stokes shift of Biexcitons was defined experimentally on the basis of two-photon absorption of Biexcitons in order to evaluate the degree of Biexciton localization quantitatively. A binding energy of Biexcitons was determined as a function of aluminum composition. The Biexciton localization due to alloy disorder resulted in a strong enhancement of the Biexciton binding energy.
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Stokes shift of Biexcitons inAlxGa1−xNepitaxial layers
Physical Review B, 2004Co-Authors: Yoichi Yamada, Yusuke Ueki, Kohzo Nakamura, Tsunemasa Taguchi, Akihiko Ishibashi, Yasutoshi Kawaguchi, Toshiya YokogawaAbstract:The effect of localization due to alloy disorder on Biexcitons in Ga-rich ${\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{N}$ ternary alloy epitaxial layers has been studied by means of photoluminescence excitation spectroscopy. A Stokes shift of Biexcitons was defined experimentally on the basis of two-photon absorption of Biexcitons in order to evaluate the degree of Biexciton localization quantitatively. A binding energy of Biexcitons was also determined as a function of aluminum composition in the ternary alloys. The Biexciton localization due to alloy disorder resulted in a strong enhancement of the Biexciton binding energy.
N. Grandjean - One of the best experts on this subject based on the ideXlab platform.
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Impact of Biexcitons on the relaxation mechanisms of polaritons in III-nitride based multi-quantum well microcavities.
Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2012Co-Authors: Pierre Corfdir, J. Levrat, G. Rossbach, R. Butté, E. Feltin, J.f. Carlin, Pierre Lefebvre, Jean-daniel Ganière, G. Christmann, N. GrandjeanAbstract:We report on the direct observation of Biexcitons in a III-nitride based multiple quantum well microcavity operating in the strong light-matter coupling regime by means of nonresonant continuous wave and time-resolved photoluminescence at low temperature. First, the Biexciton dynamics is investigated for the bare active medium (multiple quantum wells alone) evidencing localization on potential fluctuations due to alloy disorder and thermalization between both localized and free excitonic and Biexcitonic populations. Then, the role of Biexcitons is considered for the full microcavity: in particular, we observe that for specific detunings the bottom of the lower polariton branch is directly fed by the radiative dissociation of either cavity Biexcitons or excitons mediated by one LO-phonon. Accordingly, minimum polariton lasing thresholds are observed, when the bottom of the lower polariton branch corresponds in energy to the exciton or cavity Biexciton first LO-phonon replica. This singular observation highlights the role of excitonic molecules in the polariton condensate formation process as being a more efficient relaxation channel when compared to the usually assumed acoustical phonon emission one.
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Biexciton-Assisted Relaxation Mechanisms In III-Nitride Based Multi-Quantum Well Microcavities.
2011Co-Authors: Pierre Corfdir, J. Levrat, G. Rossbach, R. Butté, E. Feltin, J.f. Carlin, Pierre Lefebvre, Jean-daniel Ganière, N. Grandjean, Benoit Deveaud-plédranAbstract:Microcavity polaritons attract nowadays a lot of interest from the scientific community as they allow for the realization of low-threshold coherent light emitters that operate up to 300 K. It is usually admitted that, at low-temperature and negative cavity detunings, the mechanism limiting the polariton lasing threshold is the relaxation of polaritons towards the bottom of the lower-polariton branch, which is mediated by scattering with acoustic phonons. However, it has been theoretically predicted that in multi quantum well (QW) microcavities, dark exciton and Biexciton states should play an important role in the overall relaxation mechanisms of cavity polaritons. Here, we address this issue through a time-resolved photoluminescence (TR-PL) study of the relaxation dynamics at 10 K of microcavity polaritons in a 3!-cavity containing 67 Al0.2Ga0.8N/GaN QWs. The vacuum Rabi splitting of our microcavity is 60 meV and cavity detunings (!) ranging between -100 and 0 meV are investigated. At 10 K, the microcavity PL at small angle is dominated by a transition at 3.63 eV attributed to lower polaritons with a small in-plane wave vector. Two additional non-dispersive lines at 3.673 and 3.693 eV are also observed. From excitation/power-dependent experiments, we attribute them to the recombination of cavity Biexcitons and localized dark excitons, respectively. We show by TR-PL that the lower polariton PL at zero-angle exhibits at all times the same PL decay as Biexcitons. From this dynamical behavior, together with the !-dependence of the Biexciton emission energy, we can describe the interplay between polaritons and Biexcitons. In particular, we demonstrate that in nitride-based multi QW microcavities, the mechanism limiting the relaxation of polaritons towards the center of the Brillouin zone is the radiative dissociation of cavity Biexcitons into lower polaritons with high in-plane wave vector.
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Direct observation of Biexciton localization dynamics in (Al,Ga)N/GaN multi quantum wells.
2011Co-Authors: Pierre Corfdir, J. Levrat, R. Butté, E. Feltin, J.f. Carlin, Pierre Lefebvre, Jean-daniel Ganière, N. Grandjean, Benoit Deveaud-plédranAbstract:Microcavity polaritons attract nowadays a lot of interest from the scientific community as they allow for the realization of low-threshold coherent light emitters that operate up to 300 K. It is usually admitted that, at low-temperature and negative cavity detunings, the mechanism limiting the polariton lasing threshold is the relaxation of polaritons towards the bottom of the lower-polariton branch, which is mediated by scattering with acoustic phonons. However, it has been theoretically predicted that in multi quantum well (QW) microcavities, dark exciton and Biexciton states should play an important role in the overall relaxation mechanisms of cavity polaritons. Here, we address this issue through a time-resolved photoluminescence (TR-PL) study of the relaxation dynamics at 10 K of microcavity polaritons in a 3!-cavity containing 67 Al0.2Ga0.8N/GaN QWs. The vacuum Rabi splitting of our microcavity is 60 meV and cavity detunings (!) ranging between -100 and 0 meV are investigated. At 10 K, the microcavity PL at small angle is dominated by a transition at 3.63 eV attributed to lower polaritons with a small in-plane wave vector. Two additional non-dispersive lines at 3.673 and 3.693 eV are also observed. From excitation/power-dependent experiments, we attribute them to the recombination of cavity Biexcitons and localized dark excitons, respectively. We show by TR-PL that the lower polariton PL at zero-angle exhibits at all times the same PL decay as Biexcitons. From this dynamical behavior, together with the !-dependence of the Biexciton emission energy, we can describe the interplay between polaritons and Biexcitons. In particular, we demonstrate that in nitride-based multi QW microcavities, the mechanism limiting the relaxation of polaritons towards the center of the Brillouin zone is the radiative dissociation of cavity Biexcitons into lower polaritons with high in-plane wave vector.
Pierre Corfdir - One of the best experts on this subject based on the ideXlab platform.
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Impact of Biexcitons on the relaxation mechanisms of polaritons in III-nitride based multi-quantum well microcavities.
Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2012Co-Authors: Pierre Corfdir, J. Levrat, G. Rossbach, R. Butté, E. Feltin, J.f. Carlin, Pierre Lefebvre, Jean-daniel Ganière, G. Christmann, N. GrandjeanAbstract:We report on the direct observation of Biexcitons in a III-nitride based multiple quantum well microcavity operating in the strong light-matter coupling regime by means of nonresonant continuous wave and time-resolved photoluminescence at low temperature. First, the Biexciton dynamics is investigated for the bare active medium (multiple quantum wells alone) evidencing localization on potential fluctuations due to alloy disorder and thermalization between both localized and free excitonic and Biexcitonic populations. Then, the role of Biexcitons is considered for the full microcavity: in particular, we observe that for specific detunings the bottom of the lower polariton branch is directly fed by the radiative dissociation of either cavity Biexcitons or excitons mediated by one LO-phonon. Accordingly, minimum polariton lasing thresholds are observed, when the bottom of the lower polariton branch corresponds in energy to the exciton or cavity Biexciton first LO-phonon replica. This singular observation highlights the role of excitonic molecules in the polariton condensate formation process as being a more efficient relaxation channel when compared to the usually assumed acoustical phonon emission one.
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Biexciton-Assisted Relaxation Mechanisms In III-Nitride Based Multi-Quantum Well Microcavities.
2011Co-Authors: Pierre Corfdir, J. Levrat, G. Rossbach, R. Butté, E. Feltin, J.f. Carlin, Pierre Lefebvre, Jean-daniel Ganière, N. Grandjean, Benoit Deveaud-plédranAbstract:Microcavity polaritons attract nowadays a lot of interest from the scientific community as they allow for the realization of low-threshold coherent light emitters that operate up to 300 K. It is usually admitted that, at low-temperature and negative cavity detunings, the mechanism limiting the polariton lasing threshold is the relaxation of polaritons towards the bottom of the lower-polariton branch, which is mediated by scattering with acoustic phonons. However, it has been theoretically predicted that in multi quantum well (QW) microcavities, dark exciton and Biexciton states should play an important role in the overall relaxation mechanisms of cavity polaritons. Here, we address this issue through a time-resolved photoluminescence (TR-PL) study of the relaxation dynamics at 10 K of microcavity polaritons in a 3!-cavity containing 67 Al0.2Ga0.8N/GaN QWs. The vacuum Rabi splitting of our microcavity is 60 meV and cavity detunings (!) ranging between -100 and 0 meV are investigated. At 10 K, the microcavity PL at small angle is dominated by a transition at 3.63 eV attributed to lower polaritons with a small in-plane wave vector. Two additional non-dispersive lines at 3.673 and 3.693 eV are also observed. From excitation/power-dependent experiments, we attribute them to the recombination of cavity Biexcitons and localized dark excitons, respectively. We show by TR-PL that the lower polariton PL at zero-angle exhibits at all times the same PL decay as Biexcitons. From this dynamical behavior, together with the !-dependence of the Biexciton emission energy, we can describe the interplay between polaritons and Biexcitons. In particular, we demonstrate that in nitride-based multi QW microcavities, the mechanism limiting the relaxation of polaritons towards the center of the Brillouin zone is the radiative dissociation of cavity Biexcitons into lower polaritons with high in-plane wave vector.
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Direct observation of Biexciton localization dynamics in (Al,Ga)N/GaN multi quantum wells.
2011Co-Authors: Pierre Corfdir, J. Levrat, R. Butté, E. Feltin, J.f. Carlin, Pierre Lefebvre, Jean-daniel Ganière, N. Grandjean, Benoit Deveaud-plédranAbstract:Microcavity polaritons attract nowadays a lot of interest from the scientific community as they allow for the realization of low-threshold coherent light emitters that operate up to 300 K. It is usually admitted that, at low-temperature and negative cavity detunings, the mechanism limiting the polariton lasing threshold is the relaxation of polaritons towards the bottom of the lower-polariton branch, which is mediated by scattering with acoustic phonons. However, it has been theoretically predicted that in multi quantum well (QW) microcavities, dark exciton and Biexciton states should play an important role in the overall relaxation mechanisms of cavity polaritons. Here, we address this issue through a time-resolved photoluminescence (TR-PL) study of the relaxation dynamics at 10 K of microcavity polaritons in a 3!-cavity containing 67 Al0.2Ga0.8N/GaN QWs. The vacuum Rabi splitting of our microcavity is 60 meV and cavity detunings (!) ranging between -100 and 0 meV are investigated. At 10 K, the microcavity PL at small angle is dominated by a transition at 3.63 eV attributed to lower polaritons with a small in-plane wave vector. Two additional non-dispersive lines at 3.673 and 3.693 eV are also observed. From excitation/power-dependent experiments, we attribute them to the recombination of cavity Biexcitons and localized dark excitons, respectively. We show by TR-PL that the lower polariton PL at zero-angle exhibits at all times the same PL decay as Biexcitons. From this dynamical behavior, together with the !-dependence of the Biexciton emission energy, we can describe the interplay between polaritons and Biexcitons. In particular, we demonstrate that in nitride-based multi QW microcavities, the mechanism limiting the relaxation of polaritons towards the center of the Brillouin zone is the radiative dissociation of cavity Biexcitons into lower polaritons with high in-plane wave vector.
André Mysyrowicz - One of the best experts on this subject based on the ideXlab platform.
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Phase-Coherent Manipulation of Cold Biexcitonic Waves
Journal of the Physical Society of Japan, 2002Co-Authors: Makoto Kuwata-gonokami, Ryo Shimano, André MysyrowiczAbstract:By using femtosecond optical pulses we create and manipulate a long-lived highly coherent Biexcitonic wave in CuCl. Phase space compression by a factor 102 in the two-photon absorption process yields a quasiparticle ensemble with a density of up to 1013 cm-3 and more than 104 Biexcitons per mode, which shows harmonic scalar wave behavior for 70 ps. The coherent Biexciton ensemble acts as a phase-dependent two-photon amplifier for optical pulses. Phase sensitivity of the light pulse transmission allows us to phase lock the two successive pulses and demonstrates the coherent control of Biexciton waves. By measuring the visibility of the Biexcitonic interference pattern we confirm a high degree of coherence of the stored excitation.
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Bose-Einstein condensation of Biexciton system in CuCl
Journal of Luminescence, 1994Co-Authors: M. Hasuo, Nobukata Nagasawa, T. Itoh, André MysyrowiczAbstract:Abstract An experiment is described which aims at detecting the coherency associated with the presence of a Bose condensate of Biexcitons in CuCl. The optical phase-conjugation signal at the two-photon resonance of theK = 0 Biexciton is detected in the presence and in the absence of a high density pool of randomly injected Biexcitons. An increase in the magnitude of the phase-conjugate signal together with a small blue shift of the Biexciton resonance are attributed to the Bose condensate.
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Progress in the Bose-Einstein condensation of Biexcitons in CuCl.
Physical review letters, 1993Co-Authors: M. Hasuo, Tadashi Itoh, Nobukata Nagasawa, André MysyrowiczAbstract:The occupancy of the K=0 ground state of the Biexciton in CuCl is measured by nonlinear optical methods. An increase of the optical phase conjugation signal is observed when a random high density of Biexcitons is injected into the crystal. The corresponding increase of coherency is attributed to a quantum attraction towards a Bose-Einstein condensate of Biexcitons.
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A New Approach to the Study of Bose‐Einstein Condensation of Biexcitons
physica status solidi (b), 1992Co-Authors: M. Hasuo, Nobukata Nagasawa, André MysyrowiczAbstract:A new method is described that allows to detect the presence of a fBose condensate of Biexcitons in a direct band gap material. It probes the accumulation of Biexcitons in the coherent k=0 state by measuring the increase of the optical phase conjugation signal of a crystal simultaneously pumped by an intense incoherent pump source. Experimental verification of the method is achieved in CuCl at low temperature. Results show an increase of the k=0 Biexciton mode occupation number by at least 8.6×10 5 when the randomly injected Biexciton density exceeds the critical value for Bose condensation
J. Levrat - One of the best experts on this subject based on the ideXlab platform.
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Impact of Biexcitons on the relaxation mechanisms of polaritons in III-nitride based multi-quantum well microcavities.
Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2012Co-Authors: Pierre Corfdir, J. Levrat, G. Rossbach, R. Butté, E. Feltin, J.f. Carlin, Pierre Lefebvre, Jean-daniel Ganière, G. Christmann, N. GrandjeanAbstract:We report on the direct observation of Biexcitons in a III-nitride based multiple quantum well microcavity operating in the strong light-matter coupling regime by means of nonresonant continuous wave and time-resolved photoluminescence at low temperature. First, the Biexciton dynamics is investigated for the bare active medium (multiple quantum wells alone) evidencing localization on potential fluctuations due to alloy disorder and thermalization between both localized and free excitonic and Biexcitonic populations. Then, the role of Biexcitons is considered for the full microcavity: in particular, we observe that for specific detunings the bottom of the lower polariton branch is directly fed by the radiative dissociation of either cavity Biexcitons or excitons mediated by one LO-phonon. Accordingly, minimum polariton lasing thresholds are observed, when the bottom of the lower polariton branch corresponds in energy to the exciton or cavity Biexciton first LO-phonon replica. This singular observation highlights the role of excitonic molecules in the polariton condensate formation process as being a more efficient relaxation channel when compared to the usually assumed acoustical phonon emission one.
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Biexciton-Assisted Relaxation Mechanisms In III-Nitride Based Multi-Quantum Well Microcavities.
2011Co-Authors: Pierre Corfdir, J. Levrat, G. Rossbach, R. Butté, E. Feltin, J.f. Carlin, Pierre Lefebvre, Jean-daniel Ganière, N. Grandjean, Benoit Deveaud-plédranAbstract:Microcavity polaritons attract nowadays a lot of interest from the scientific community as they allow for the realization of low-threshold coherent light emitters that operate up to 300 K. It is usually admitted that, at low-temperature and negative cavity detunings, the mechanism limiting the polariton lasing threshold is the relaxation of polaritons towards the bottom of the lower-polariton branch, which is mediated by scattering with acoustic phonons. However, it has been theoretically predicted that in multi quantum well (QW) microcavities, dark exciton and Biexciton states should play an important role in the overall relaxation mechanisms of cavity polaritons. Here, we address this issue through a time-resolved photoluminescence (TR-PL) study of the relaxation dynamics at 10 K of microcavity polaritons in a 3!-cavity containing 67 Al0.2Ga0.8N/GaN QWs. The vacuum Rabi splitting of our microcavity is 60 meV and cavity detunings (!) ranging between -100 and 0 meV are investigated. At 10 K, the microcavity PL at small angle is dominated by a transition at 3.63 eV attributed to lower polaritons with a small in-plane wave vector. Two additional non-dispersive lines at 3.673 and 3.693 eV are also observed. From excitation/power-dependent experiments, we attribute them to the recombination of cavity Biexcitons and localized dark excitons, respectively. We show by TR-PL that the lower polariton PL at zero-angle exhibits at all times the same PL decay as Biexcitons. From this dynamical behavior, together with the !-dependence of the Biexciton emission energy, we can describe the interplay between polaritons and Biexcitons. In particular, we demonstrate that in nitride-based multi QW microcavities, the mechanism limiting the relaxation of polaritons towards the center of the Brillouin zone is the radiative dissociation of cavity Biexcitons into lower polaritons with high in-plane wave vector.
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Direct observation of Biexciton localization dynamics in (Al,Ga)N/GaN multi quantum wells.
2011Co-Authors: Pierre Corfdir, J. Levrat, R. Butté, E. Feltin, J.f. Carlin, Pierre Lefebvre, Jean-daniel Ganière, N. Grandjean, Benoit Deveaud-plédranAbstract:Microcavity polaritons attract nowadays a lot of interest from the scientific community as they allow for the realization of low-threshold coherent light emitters that operate up to 300 K. It is usually admitted that, at low-temperature and negative cavity detunings, the mechanism limiting the polariton lasing threshold is the relaxation of polaritons towards the bottom of the lower-polariton branch, which is mediated by scattering with acoustic phonons. However, it has been theoretically predicted that in multi quantum well (QW) microcavities, dark exciton and Biexciton states should play an important role in the overall relaxation mechanisms of cavity polaritons. Here, we address this issue through a time-resolved photoluminescence (TR-PL) study of the relaxation dynamics at 10 K of microcavity polaritons in a 3!-cavity containing 67 Al0.2Ga0.8N/GaN QWs. The vacuum Rabi splitting of our microcavity is 60 meV and cavity detunings (!) ranging between -100 and 0 meV are investigated. At 10 K, the microcavity PL at small angle is dominated by a transition at 3.63 eV attributed to lower polaritons with a small in-plane wave vector. Two additional non-dispersive lines at 3.673 and 3.693 eV are also observed. From excitation/power-dependent experiments, we attribute them to the recombination of cavity Biexcitons and localized dark excitons, respectively. We show by TR-PL that the lower polariton PL at zero-angle exhibits at all times the same PL decay as Biexcitons. From this dynamical behavior, together with the !-dependence of the Biexciton emission energy, we can describe the interplay between polaritons and Biexcitons. In particular, we demonstrate that in nitride-based multi QW microcavities, the mechanism limiting the relaxation of polaritons towards the center of the Brillouin zone is the radiative dissociation of cavity Biexcitons into lower polaritons with high in-plane wave vector.