Atomically precise superlattice potential imposed on a two-dimensional electron gas

Störmer, H. L.; Pfeiffer, L. N.; Baldwin, K. W.; West, K. W.; Spector, J.

doi:10.1063/1.104528

Cited by 93 publications

(39 citation statements)

References 12 publications

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“…4 At the intersection, a bound quantum wire state ͑T-QWR state͒ forms due to the reduction of the quantization energy. Such structures can be realized in the Al x Ga 1Ϫx As material system by the cleaved-edge overgrowth technique, [5][6][7][8][9] where both confinement dimensions are controlled by the high accuracy of the molecular-beam epitaxy ͑MBE͒. The photoluminescence of these structures, attributed to the T-QWR state transition, was demonstrated to originate from the T intersections by optical near-field spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Transient four-wave mixing in T-shaped GaAs quantum wires

1999

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The binding energy of excitons and biexcitons and the exciton dephasing in T-shaped GaAs quantum wires is investigated by transient four-wave mixing. The T-shaped structure is fabricated by cleaved-edge overgrowth, and its geometry is engineered to optimize the one-dimensional confinement. In this wire of 6.6 ϫ24 nm 2 size, we find a one-dimensional confinement of more than 20 meV, an inhomogeneous broadening of 3.4 meV, an exciton binding energy of 12 meV, and a biexciton binding energy of 2.0 meV. A dispersion of the homogeneous linewidth within the inhomogeneous broadening due to phonon-assisted relaxation is observed. The exciton acoustic-phonon-scattering coefficient of 6.1Ϯ0.5 eV/K is larger than in comparable quantum-well structures. ͓S0163-1829͑99͒04147-8͔

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Section: Introductionmentioning

confidence: 99%

Transient four-wave mixing in T-shaped GaAs quantum wires

1999

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“…The fabrication by lithographic methods is limited to an accuracy of about ten nanometers, and thus gives rise to a strong inhomogeneous broadening of the electronic properties. [5][6][7] There are some methods to overcome this difficulty, e.g., by the overgrowth of cleaved quantum-well structures [8][9][10][11] as well as etched V grooves on GaAs substrates. 2,12 However, these methods require involved processing.…”

Section: Introductionmentioning

confidence: 99%

Influence of the interface corrugation on the subband dispersions and the optical properties of (113)-oriented GaAs/AlAs superlattices

et al. 1996

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We report on the influence of the interface corrugation in ͑113͒-grown GaAs/AlAs superlattices on their band-edge optical properties both in theory and experiment. We calculate the subband dispersions and the optical anisotropies in a multiband k•p formalism. The dominating contribution to the optical anisotropies is found to be due to the intrinsic properties of the valence-band structure. The corrugation modifies the density of states only slightly, giving no evidence of a quantum-wire behavior. By comparing the calculation with the experimental optical anisotropy, we can estimate the corrugation height to be at most 2 monolayers. The experiments show that deviations from the regular corrugation lead to an anisotropic interface disorder. This gives rise to an enhanced anisotropy of the band-edge states, which was so far attributed to the corrugation itself. The luminescence of the localized type-I states at the band-edge show an enhanced optical anisotropy in comparison to the luminescence of the extended states, revealing the anisotropic nature of their localization sites. In type-II samples, deeply localized, isolated type-I states (⌫ quantum boxes͒ dominate the luminescence at short delays after pulsed excitation and at higher lattice temperatures or excitation densities, due to their strong radiative decay compared to the type-II states. These quantum boxes are observed individually by high spatial and spectral resolution. ͓S0163-1829͑96͒06039-0͔

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“…Changing the magnetic field allows us to vary l B relative to λ; and changing the gate voltage allows us to tune the SL potential strength relative to LL spacing. The relative abruptness, bipolarity of charge carriers, large modulation and unequally spaced LLs distinguishes the present work from the previous work on 1D SL using 2DEGS systems [1][2][3][4]14].Apart from the length scales, we also study the energy scales involved. The competition between SL amplitude (V 0 ) and LL spacing (hω c , whereh = h/2π, h being the Planck's constant, and ω c is the cyclotron frequency) gives rise to three regimes.…”

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confidence: 59%

“…Crossed electric and magnetic fields modify the wavefunction of the Landau Levels (LLs) -a phenomenon unique to graphene. In the region of copropagating electrons and holes at the interface, the electric field is high enough to modify the Landau levels resulting in increased scattering that tunes equilibration of edge states and this results in large longitudinal resistance.Magnetotransport across one-dimensional superlattice (SL) had been studied in two-dimensional electron gas in semiconductor heterostructures (2DEGS) [1][2][3][4][5][6], reporting dissipationless transport across high potential barriers [1] and magnetic commensurability oscillations in longitudinal resistance [3]. The motivation was to study various competing length scales and energy scales between tunable SL potential and quantum Hall system.…”

mentioning

confidence: 99%

“…Magnetotransport across one-dimensional superlattice (SL) had been studied in two-dimensional electron gas in semiconductor heterostructures (2DEGS) [1][2][3][4][5][6], reporting dissipationless transport across high potential barriers [1] and magnetic commensurability oscillations in longitudinal resistance [3]. The motivation was to study various competing length scales and energy scales between tunable SL potential and quantum Hall system.…”

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confidence: 99%

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Tuning equilibration of quantum Hall edge states in graphene – Role of crossed electric and magnetic fields

Dubey

Deshmukh

2016

Solid State Communications

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We probe quantum Hall effect in a tunable 1-D lateral superlattice (SL) in graphene created using electrostatic gates. Lack of equilibration is observed along edge states formed by electrostatic gates inside the superlattice. We create strong local electric field at the interface of regions of different charge densities. Crossed electric and magnetic fields modify the wavefunction of the Landau Levels (LLs) -a phenomenon unique to graphene. In the region of copropagating electrons and holes at the interface, the electric field is high enough to modify the Landau levels resulting in increased scattering that tunes equilibration of edge states and this results in large longitudinal resistance.Magnetotransport across one-dimensional superlattice (SL) had been studied in two-dimensional electron gas in semiconductor heterostructures (2DEGS) [1][2][3][4][5][6], reporting dissipationless transport across high potential barriers [1] and magnetic commensurability oscillations in longitudinal resistance [3]. The motivation was to study various competing length scales and energy scales between tunable SL potential and quantum Hall system. Graphene offers the advantage of large cyclotron gap allowing quantum Hall effect to be observed at room temperature [7][8][9]. Substrate induced SL in graphene in the presence of magnetic field led to the experimental observation of Hofstadter butterfly physics [10][11][12]. The ability to create abrupt (∼ 10 nm) tunable barriers in graphene allows new aspects to be explored. In addition, new physics, due to the role of crossed electric and magnetic field, that cannot be seen in conventional 2DEGS can be studied in SL structures based on graphene.In this letter, we study magneto transport in an electrostatically defined 1D lateral SL in graphene [13]. In our device we apply a perpendicular magnetic field and periodically modulate the charge carrier density in adjacent "ribbons" of graphene, tuning from an array of p-p' (or n-n' ) to an array of p-n' junctions. Changing the magnetic field allows us to vary l B relative to λ; and changing the gate voltage allows us to tune the SL potential strength relative to LL spacing. The relative abruptness, bipolarity of charge carriers, large modulation and unequally spaced LLs distinguishes the present work from the previous work on 1D SL using 2DEGS systems [1][2][3][4]14].Apart from the length scales, we also study the energy scales involved. The competition between SL amplitude (V 0 ) and LL spacing (hω c , whereh = h/2π, h being the Planck's constant, and ω c is the cyclotron frequency) gives rise to three regimes. When V 0 >>hω c , SL effect dominates giving rise to extra Dirac points [15]. In the other extreme when V 0 <

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Atomically precise superlattice potential imposed on a two-dimensional electron gas

Abstract: Articles you may be interested inQuasiperiodic functions theory and the superlattice potentials for a two-dimensional electron gas

Cited by 93 publications

References 12 publications

Transient four-wave mixing in T-shaped GaAs quantum wires

Transient four-wave mixing in T-shaped GaAs quantum wires

Influence of the interface corrugation on the subband dispersions and the optical properties of (113)-oriented GaAs/AlAs superlattices

Tuning equilibration of quantum Hall edge states in graphene – Role of crossed electric and magnetic fields

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