Electron transport in dual-gated three-layer MoS₂

We investigate the conduction band of a dual-gated three layer MoS₂ by means of magnetotransport experiments. The overall carrier density is tuned by both top and bottom gates. By applying an asymmetric gate voltage configuration, electrons accumulate in the layer closest to the positively biased electrode, and the three-layer MoS₂ behaves electronically like a monolayer. In the situation where a positive voltage is applied to both gates leads to the occupation of all three layers. Shubnikov-de Haas oscillations originating from several bands are separately attributed to carrier densities in the top and bottom layers. We find a two-fold Landau level degeneracy for each band, suggesting that the minima of the conduction band lie at the K points of the first Brillouin zone, in contrast to band structure calculations, which report minima at the Q points. Even though the inter-layer tunnel coupling seems to leave the low energy conduction band unaffected, we observe scattering between the outermost layers, while the middle layer remains decoupled due to the inverted spin/valley symmetry.