Tunable Γ−<i>Κ</i> Valley Populations in Hole-Doped Trilayer WSe<sub>2</sub>
ORAL
Abstract
Semiconducting transition metal dichalcogenides (TMDs) exhibit thickness dependent bandstructures with the monolayers possessing a direct gap at the K points of the Brillouin zone. Beyond the monolayer limit, the TMD bandstructure becomes more complicated with the band extrema locations in few-layer TMDs remaining an open question for the vast majority of TMDs. Here, we address the valence band maxima locations in trilayer WSe2 using magnetotransport measurements in high-mobility, h-BN encapsulated, dual-gated samples. Shubnikov-de Haas oscillations evince holes populating two distinct subbands with effective masses m* = 0.5me belonging to the K valley, and m* = 1.2me belonging to the Γ valley of trilayer WSe2; me is the bare electron mass. At a fixed total hole density, the K and Γ occupations can be tuned by an applied transverse electric field (E), with Γ being the lowest energy state at low E-field and K being the lowest energy state at high E-field. Ab-initio calculations support these findings and explain the shift of the valence band maxima, and the consequent transfer of holes from Γ to K with increasing E-field.
*This work was supported by NRI SWAN, and Intel Corp. A portion of this work was performed at the National High Magnetic Field Laboratory, Tallahassee, Florida.
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Presenters
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Hema Movva
- The University of Texas at Austin
- Univ of Texas, Austin