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Title: Electronic and thermoelectric properties of van der Waals materials with ring-shaped valence bands

The valence band of a variety of few-layer, two-dimensional materials consist of a ring of states in the Brillouin zone. The energy-momentum relation has the form of a “Mexican hat” or a Rashba dispersion. The two-dimensional density of states is singular at or near the band edge, and the band-edge density of modes turns on nearly abruptly as a step function. The large band-edge density of modes enhances the Seebeck coefficient, the power factor, and the thermoelectric figure of merit ZT. Electronic and thermoelectric properties are determined from ab initio calculations for few-layer III–VI materials GaS, GaSe, InS, InSe, for Bi{sub 2}Se{sub 3}, for monolayer Bi, and for bilayer graphene as a function of vertical field. The effect of interlayer coupling on these properties in few-layer III–VI materials and Bi{sub 2}Se{sub 3} is described. Analytical models provide insight into the layer dependent trends that are relatively consistent for all of these few-layer materials. Vertically biased bilayer graphene could serve as an experimental test-bed for measuring these effects.
Authors:
;  [1] ;  [2]
  1. Laboratory for Terahertz and Terascale Electronics, Department of Electrical and Computer Engineering, University of California, Riverside, California 92521 (United States)
  2. Department of Physics and the Center of Theoretical and Computational Physics, The University of Hong Kong, Pokfulam Road, Hong Kong (China)
Publication Date:
OSTI Identifier:
22494769
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 118; Journal Issue: 7; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; BISMUTH SELENIDES; BRILLOUIN ZONES; DENSITY; DENSITY OF STATES; ELECTRONIC STRUCTURE; GALLIUM SELENIDES; GRAPHENE; INDIUM SELENIDES; LAYERS; PERFORMANCE; POWER FACTOR; THERMOELECTRIC PROPERTIES; TWO-DIMENSIONAL SYSTEMS; VALENCE; VAN DER WAALS FORCES