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Alexandrou, Antigoni; Kash, J. A.; Méndez, E. E.; Zachau, M.; Jiao, Hong; Fukuzawa, T.; Hase, Yoshihiro

doi:10.1103/physrevb.42.9225

Cited by 103 publications

(88 citation statements)

References 19 publications

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“…Magnitude of the applied voltage determines the amplitude of potential oscillations V 0 as well as the constant component E av = {0, 0, E av z } of the electric field. The latter determines the dipole moment of the excitons in single QWs and their lifetime in the radiation zone 115 . Proposed realization has two important limitations.…”

Section: Physical Realizationmentioning

confidence: 99%

Anisotropic superfluidity of two-dimensional excitons in a periodic potential

2017

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We study anisotropies of helicity modulus, excitation spectrum, sound velocity and angle-resolved luminescence spectrum in a two-dimensional system of interacting excitons in a periodic potential. Analytical expressions for anisotropic corrections to the quantities characterizing superfluidity are obtained. We consider particularly the case of dipolar excitons in quantum wells. For GaAs/AlGaAs heterostructures as well as MoS2/hBN/MoS2 and MoSe2/hBN/WSe2 transition metal dichalcogenide bilayers estimates of the magnitude of the predicted effects are given. We also present a method to control superfluid motion and to determine the helicity modulus in generic dipolar systems.

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Section: Physical Realizationmentioning

confidence: 99%

Anisotropic superfluidity of two-dimensional excitons in a periodic potential

2017

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confidence: 99%

“…For even higher fields the decay time decreased again, and at E = 40 kV/cm it dropped to 250 ps. These two regimes have been explained in terms of a reduction of wave function overlap and of tunneling of the carriers out of the wells, respectively [15,16].A measure of the exciton-exciton interaction is the energy difference between the PL spectra of the X + e1hh1 and X − e1hh1 excitons, plotted in the insets of Fig. 2 for three representative electric fields.…”

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confidence: 99%

Electric-Field Tuning of Spin-Dependent Exciton-Exciton Interactions in Coupled Quantum Wells

et al. 1999

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We have shown experimentally that an electric field decreases the energy separation between the two components of a dense spin-polarized exciton gas in a coupled double quantum well, from a maximum splitting of ∼ 4 meV to zero, at a field of ∼35 kV/cm. This decrease, due to the fieldinduced deformation of the exciton wavefunction, is explained by an existing calculation of the change in the spin-dependent exciton-exciton interaction with the electron-hole separation. However, a new theory that considers the modification of screening with that separation is needed to account for the observed dependence on excitation power of the individual energies of the two exciton components.PACS numbers: 78.47.+p, 71.70.Gm, 78.66.Fd Spin dependent exciton-exciton interactions in low dimensionality semiconductors have been studied extensively during this decade [1][2][3][4][5][6][7][8]. The first observation of an energy splitting between the two spin polarized components of an exciton gas without a magnetic field was reported by Damen et al. [1]. Since then this effect has been considered both experimentally [5,8] and theoretically [6,7]. Fernández-Rossier et al. attributed that splitting to a density-and spin-dependent modification of the two dimensional (2D) exciton binding energy (E 2D ) by two competing processes [6,7]. One of these many-body processes is the exchange interaction (I EC ) between electrons (and holes) of different excitons, which always increases E 2D in proportion to the spin-polarized exciton density, so that the change, ∆E ± 2D , is ∆E ± 2D ∝ n ± X I EC , where n ± X refers to the spin +1 and -1 exciton populations, respectively [9]. The second process is the vertex correction (I V C ) to the Coulomb interaction between electrons and holes of different excitons. This correction effectively reduces the electron-hole attraction due to the occupation of final states in the electron-hole scattering processes and lowers E 2D proportionally to n ± X I V C . Hence, neglecting the small coupling between +1 and -1 states due to valence band mixing, the total change of the exciton binding energy is ∆E ± 2D ∝ n ± X (I EC − I V C ).When the overlap between the electron and hole wavefunctions is large the vertex correction outweighs exchange effects (that is, (I EC − I V C ) < 0) and the exciton binding energy is reduced (with respect to that of a single exciton). Moreover, when n + X > n − X , the reduction is such that |∆E + 2D | > |∆E − 2D |, leading to a smaller binding energy of the +1 excitons than that of the -1. As a result an energy splitting δǫ between the components of a dense spin-polarized quasi 2D exciton gas is expected. Such a splitting has been observed in time-resolved photoluminescence (PL) experiments in quantum wells, in which a circularly polarized light pulse (σ + ) creates excitons with spin +1 that gradually relax into the spin -1 state, until both populations are equal. The PL spectrum corresponding to the spin +1 exciton has been found to be at higher energy than that of the -1 exciton,...

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“…Impurity assisted tunneling between the excited and ground state sub-bands for heavyholes within symmetric GaAs/Al 0.3 Ga 0.7 As CQW similar to those studied were reported, which showed a 340 ps tunneling time for electric field of ~16 kV/cm [91]. Upon relaxation to the respective ground sub-band states in times on the order of sub-nanoseconds, the mutually coulomb attraction of electrons and holes dominates to form excitons (Xs).…”

Section: Photoluminescence and Life Cycle Of Excitonsmentioning

confidence: 81%

Spatially indirect excitons in coupled quantum wells

Lai¹

2004

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Electric-field effects on exciton lifetimes in symmetric coupled GaAs/Al0.3Ga0.7

Cited by 103 publications

References 19 publications

Anisotropic superfluidity of two-dimensional excitons in a periodic potential

Anisotropic superfluidity of two-dimensional excitons in a periodic potential

Electric-Field Tuning of Spin-Dependent Exciton-Exciton Interactions in Coupled Quantum Wells

Spatially indirect excitons in coupled quantum wells

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