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

By D. Wickramaratne, F. Zahid, Roger K. Lake. 2014

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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 Bi2Se3, 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 Bi2Se3 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.

Subfields: Atomic and Molecular Physics, and Optics, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/7694d0de0296b632f34f3d5dcaac446a94e552c1

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In Atomic and Molecular Physics, and Optics

In Materials Chemistry

Citations in the corpus

Production and processing of graphene and related materials (2020, background): “Electronic, thermal and optical properties of these flakes are still largely unknown [1118, 1121], although crucial to the implementation in several technologies, including molecular sensing [1106], high-performance thermoelectric devices with low thermal conductivity [1112], phase-change memories [”