Electronic and Thermoelectric Properties of Few-Layer Transition Metal Dichalcogenides

2014/01/31 by Darshana Wickramaratne, Ferdows Zahid, Roger K. Lake · 3 citations
Physics and Astronomy · #cond-mat.mtrl-sci #cond-mat.mes-hall

paper · pdf · doi:10.1063/1.4869142

arxiv created 2014/03/07 · arxiv updated 2014/04/03

Abstract

The electronic and thermoelectric properties of one to four monolayers of MoS₂, MoSe₂, WS₂, and WSe₂ are calculated. For few layer thicknesses,the near degeneracies of the conduction band K and Σ valleys and the valence band Γ and K valleys enhance the n-type and p-type thermoelectric performance. The interlayer hybridization and energy level splitting determine how the number of modes within k_BT of a valley minimum changes with layer thickness. In all cases, the maximum ZT coincides with the greatest near-degeneracy within k_BT of the band edge that results in the sharpest turn-on of the density of modes. The thickness at which this maximum occurs is, in general, not a monolayer. The transition from few layers to bulk is discussed. Effective masses, energy gaps, power-factors, and ZT values are tabulated for all materials and layer thicknesses.

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