Electric Field Tuning of Interlayer Coupling in Non-centrosymmetric 3R-MoS2 with Electric Double Layer Interface.

Interlayer coupling in two-dimensional (2D) layered materials plays an important role in controlling their properties. 2H- and 3R-MoS2 with different stacking orders and resulting interlayer coupling have been recently discovered to have different band structures and contrast behavior in valley physics. However, the role of carrier doping on interlayer coupling in 2D materials remains elusive. Here, based on the electric-double layer interface, we demonstrated the experimental observation of carrier-doping enhanced interlayer coupling in 3R-MoS2. A remarkable tuning of interlayer Raman modes can be observed by changing stacking sequence and carrier doping near their monolayer limit. The modulated interlayer vibration modes originated from the interlayer coupling show a doping-induced blue shift and are supposed to be associated with the interlayer coupling enhancement, which is further verified by our first-principles calculations. Such an electrical control of interlayer coupling of layered materials in electrical gating geometry provides a new degree of freedom to modify the physical properties in 2D materials.