Ultrafast Nonequilibrium Dynamics of Intersubband Excitations in Quasi-two-dimensional Semiconductors

Woerner, M.; Elsaesser, Thomas

doi:10.1007/978-1-4613-0203-2_2

Cited by 4 publications

(4 citation statements)

References 271 publications

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“…To obtain the transport coefficients and the figure of merit, we need to calculate the phonon-assisted currents through the system. The Hamiltonian of the inter-band electron-phonon coupling is [27] 7…”

Section: 'Ideal' Figure Of Meritmentioning

confidence: 99%

“…However, for the superlattice structures studied in this work, the transition should be very much like the inter-subband transitions in semiconductor quantum wells. In the latter, experimental and theoretical investigations (see[27]) revealed that the optical-phonon interaction (especially confined and interface phonons) dominates the inter-subband scattering. This supports our assumption that the inter-miniband transitions in the superlattice-based device are dominated by the optical-phonon processes.…”

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confidence: 99%

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Three-terminal semiconductor junction thermoelectric devices: improving performance

2013

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A three-terminal thermoelectric device based on a p-i-n semiconductor junction is proposed, where the intrinsic region is mounted onto what is typically a bosonic thermal terminal. Remarkably, the figure of merit of the device is governed also by the energy distribution of the bosons participating in the transport processes, in addition to the electronic. An enhanced figure of merit can be obtained when the relevant distribution is narrow and the electron-boson coupling is strong (such as for optical phonons). We study the conditions for which the figure of merit of the three-terminal junction can be greater than those of the usual thermoelectrical devices made of the same material. A possible setup with a high figure of merit, based on Bi 2 Te 3 /Si superlattices, is proposed.

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Section: 'Ideal' Figure Of Meritmentioning

confidence: 99%

mentioning

confidence: 99%

Three-terminal semiconductor junction thermoelectric devices: improving performance

2013

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“…For higher electron concentrations, many-body effects mediated by the long-range Coulomb interaction come into play and alter both the position and the lineshape of the intersubband transition. A brief review of such many-body effects has been given in [36].…”

Section: Optical Intersubband Transitions and Carrier Relaxation Afte...mentioning

confidence: 99%

“…The exact value depends on the amount of excess energy and on the lattice temperature. A review of carrier relaxation after intersubband excitation has been presented in [36].…”

Section: Optical Intersubband Transitions and Carrier Relaxation Afte...mentioning

confidence: 99%

Coherent charge transport in semiconductor quantum cascade structures

Woerner

Reimann

Elsaesser³

2004

J. Phys.: Condens. Matter

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Quantum cascade structures have found extensive application in electrically driven semiconductor lasers working in the mid- to far-infrared spectral range. Optical amplification in such unipolar devices is based on a population inversion between quasi-two-dimensional conduction subbands in coupled quantum wells. The population inversion in the active region is generated by electrons tunnelling from an injector region through a barrier into the upper laser subband and by ultrafast extraction of these electrons out of the lower laser subband through a barrier into the next injector region. Such transport processes on ultrafast timescales have been the subject of extensive experimental and theoretical work without, however, reaching a clear physical picture of the microscopic electron dynamics. In this review, we report a comprehensive experimental study of electron transport in electrically driven quantum cascade structures. Ultrafast quantum transport from the injector into the upper laser subband is investigated by mid-infrared pump–probe experiments directly monitoring the femtosecond saturation and subsequent recovery of electrically induced optical gain. For low current densities, low lattice temperatures and low pump pulse intensities, the charge transport is dominantly coherent, leading to pronounced gain oscillations due to the coherent motion of electron wavepackets. For higher current densities, lattice temperatures, or pump intensities, the gain recovery shows an additional incoherent component, which essentially follows the pump-induced heating and subsequent cooling of the carrier gas in the injector.

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Hot Electron Cooling in n-Doped Colloidal Nanoplatelets Following Near-Infrared Intersubband Excitation

Wang,

Zhu,

Wang

et al. 2024

Nano Lett.

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Intersubband transition was recently discovered in colloidal nanoplatelets, but the associated intersubband carrier relaxation dynamics remains poorly understood. In particular, it is crucial to selectively excite the intersubband transition and to follow the hot electron dynamics in the absence of valence-band holes. This is achieved herein by exciting the predoped electrons in CdSe/ZnS nanoplatelets using near-infrared femtosecond pulses and monitoring nonequilibrium electron dynamics using broad-band visible pulses. We find that the n = 2 electrons relax to the n = 1 subband and establish a Fermi−Dirac distribution within 200 fs, and finally reach an equilibrium with the lattice within a few ps. The cooling dynamics depend mainly on the excitation fluence but weakly on the doping density and the lattice temperature. These characteristics are well captured by our numerical simulation that explicitly accounts for the state occupation effect and optical phonon scattering.

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Ultrafast Nonequilibrium Dynamics of Intersubband Excitations in Quasi-two-dimensional Semiconductors

Cited by 4 publications

References 271 publications

Three-terminal semiconductor junction thermoelectric devices: improving performance

Three-terminal semiconductor junction thermoelectric devices: improving performance

Coherent charge transport in semiconductor quantum cascade structures

Hot Electron Cooling in n-Doped Colloidal Nanoplatelets Following Near-Infrared Intersubband Excitation

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