Gate-tunable band-edge in few-layer MoS$_2$

Abstract

Transition metal dichalcogenides (TMDs) have garnered significant research interest due to the variation in band-edge locations within the hexagonal Brillouin zone between single-layer and bulk configurations. In monolayers, the conduction band minima are centered at the $K$-points, whereas in multilayers, they shift to the $Q$-points, midway between the $\Gamma$ and $K$ points. In this study, we conduct magnetotransport experiments to measure the occupation in the $Q$ and $K$ valleys in fourlayer molybdenum disulfide (MoS$_2$). We demonstrate electrostatic tunability of the conduction band edge by combining our experimental results with a hybrid $k\cdot p$ tight-binding model that accounts for interlayer screening effects in a self-consistent manner. Furthermore, we extend our model to bilayer and trilayer MoS$_2$, reconciling prior experimental results and quantifying the tunable range of band edges in atomically thin TMDs.