Quantitative Determination of Interlayer Electronic Coupling in Bilayer Transition Metal Dichalcogenides

Wei-Ting Hsu^1,6*, Jiamin Quan¹, Peng-Jen Chen², Wen-Hao Chang^3,4, Xiaoqin Li¹, Jung-Fu Lin⁵, Chih-Kang Shih¹

¹Department of Physics, The University of Texas at Austin, Austin, Texas, USA
²Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
³Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan
⁴Center for Emergent Functional Matter Science, National Chiao Tung University, Hsinchu, Taiwan
⁵Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas, USA
⁶Department of Physics, National Tsing Hua University, Hsinchu, Taiwan

* Presenter:Wei-Ting Hsu, email:wthsu@phys.nthu.edu.tw

Interlayer electronic coupling in van der Waal (vdW) bilayer plays a critical role in determining the overall electronic properties. In particular, the coupling strength is dictated by the stacking configuration, the interlayer spacing and the critical point of the Brillouin zone. While the first one has been experimentally established, the latter two still remain largely unexplored. Here, by measuring the excitonic transition of the bilayer MoS₂ in high-pressure diamond anvil cell, we quantitatively determined the interlayer coupling at the K, Q and Γ points. The coupling strength we obtained at K point is ~40 meV, which can be increased to more than 100 meV with a reduced interlayer spacing of ~8%. In addition, the energy evolution of the indirect gap is used to determine the coupling strength at the Q and Γ points. The experimental results are compared with density functional theory. Our work confirms the great potential in in-situ manipulating vdW bilayers using compressive pressure.

Keywords: interlayer electronic coupling, van der Waal bilayer, high-pressure experiment