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Brillouin zone

About: Brillouin zone is a research topic. Over the lifetime, 13849 publications have been published within this topic receiving 383077 citations.


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TL;DR: It is shown that the optical band-gap absorption of monolayer WS2 is governed by competing resonances arising from one neutral and two distinct negatively charged excitons whose contributions to the overall absorption of light vary as a function of temperature and carrier concentration.
Abstract: We present a comprehensive optical study of thin films of tungsten disulfide (WS$_2$) with layer thicknesses ranging from mono- to octalayer and in the bulk limit. It is shown that the optical band-gap absorption of monolayer WS$_2$ is governed by competing resonances arising from one neutral and two distinct negatively charged excitons whose contributions to the overall absorption of light vary as a function of temperature and carrier concentration. The photoluminescence response of monolayer WS$_2$ is found to be largely dominated by disorder/impurity- and/or phonon-assisted recombination processes. The indirect band-gap luminescence in multilayer WS$_2$ turns out to be a phonon-mediated process whose energy evolution with the number of layers surprisingly follows a simple model of a two-dimensional confinement. The energy position of the direct band-gap response (A and B resonances) is only weakly dependent on the layer thickness, which underlines an approximate compensation of the effect of the reduction of the exciton binding energy by the shrinkage of the apparent band gap. The A-exciton absorption-type spectra in multilayer WS$_2$ display a non-trivial fine structure which results from the specific hybridization of the electronic states in the vicinity of the K-point of the Brillouin zone. The effects of temperature on the absorption-like and photoluminescence spectra of various WS$_2$ layers are also quantified.

83 citations

Journal ArticleDOI
TL;DR: In this paper, the ideal strength of silicon is predicted along various loading paths using density functional theory, and the stress-strain curves are calculated under uniaxial tension, relaxed shear, and nonlinear deformation conditions.
Abstract: The ideal strength of silicon is predicted along various loading paths using density functional theory. Stress-strain curves are calculated under uniaxial tension, relaxed shear, and uniaxial deformation conditions. In order to check the stability of the deformation paths, the phonon spectra and the stiffness tensors are computed within density-functional perturbation theory. A second-order phase transition is found to occur before the elastic instability when applying a {111} relaxed shear. In all the other deformation conditions, the first predicted instabilities are located at the center of the Brillouin zone. Finally, the crystallographic nature of the instabilities is investigated by the calculation of the phonon eigendisplacements and by the decomposition of the stiffness tensors.

83 citations

Journal ArticleDOI
TL;DR: In this paper, a wide range of stoichiometries, 0≤x≤0.8, was extended to include a wide variety of stochastic properties.
Abstract: TiNx films of various composition have been prepared by reactive‐ion‐beam sputtering at a deposition temperature of 50 °C. Young’s modulus E and hardness H of these films were measured by a depth‐sensing nanoindentation technique, whereas the shear modulus G was obtained by a measurement of the velocity of the acoustic surface wave by Brillouin light scattering. The study was extended over a wide range of stoichiometries, 0≤x≤0.8. A proportionality between E and H has been observed.

83 citations

Journal ArticleDOI
TL;DR: In this paper, a new model for impact ionization in Si is presented, which goes beyond the limitations of the Keldysh formula and is based on a more realistic scheme developed starting from a first-order perturbation theory.
Abstract: A new model for impact ionization in Si is presented, which goes beyond the limitations of the Keldysh formula and is based on a more realistic scheme developed starting from a first‐order perturbation theory. This scattering mechanism is modeled by an extended band structure which includes many bands for electrons and one band for holes in a finite Brillouin zone. Some processes have been identified to bring the dominant contribution to the scattering probability, in the present approach, for electron energies ranging up to 3 eV. Expressions for the differential and integrated scattering probabilities have been obtained which are consistent with the band model and can be included in a Monte Carlo simulation of the electron gas. Results for transport quantities are shown for a bulk material in presence of homogeneous and static electric fields under physical conditions where impact ionization influences the carrier dynamics. A comparison with theoretical and experimental data from the literature is also g...

83 citations

Journal ArticleDOI
TL;DR: In this article, selection rules for intervalley scattering between the lowest conduction-band minima at the Brillouin zone of a III-V semiconductor were presented for theories of the Gunn effect.
Abstract: Selection rules are presented for intervalley scattering between the lowest conduction-band minima at $\ensuremath{\Gamma}$, $X$, and $L$ in the Brillouin zone of a III-V semiconductor. These selection rules are required for theories of the Gunn effect. The two most important crystals experimentally are GaAs, where longitudinal optic phonons cause the intervalley scattering, and InP, where longitudinal acoustic phonons produce the scattering.

83 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023430
2022957
2021463
2020543
2019568
2018587