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Electron–Phonon Coupling Constant of 2H-MoS₂(0001) from Helium-Atom Scattering

Author:
Anemone, Gloria, Taleb, Amjad Al, Benedek, Giorgio, Castellanos-Gomez, Andres, Farías, Daniel
Source:
Journal of physical chemistry 2019 v.123 no.6 pp. 3682-3686
ISSN:
1932-7455
Subject:
energy, physical chemistry, semiconductors, surface temperature
Abstract:
We have studied the (0001) surface of 2H-MoS₂ by means of helium-atom scattering (HAS). The electron–phonon coupling constant, λ, of this system has been determined by measuring the thermal attenuation of the specular peak at surface temperatures between 100 and 500 K. HAS diffraction also reveals a 3% planar dilation of the surface layer, whereas step interference measured at low incidence energy indicates a slight contraction of the surface layer thickness. By employing a recently developed quantum-theoretical approach applied to the case of layered degenerate semiconductors for a carrier concentration of 5 × 10¹² cm–², we find λ ∼ 0.40. We discuss the derivation of λ from HAS reflectivity data in this class of two-dimensional materials with regard to its dependence on the carrier density and effective mass.
Agid:
6310010