Crystallography-Driven Interfacial Hybridization at MoS₂/Bi van der Waals Interfaces

Yan-Ruei Lin^1*, Hung-Chang Hsu², Li-Sheng Lin¹, Hao-Yu Chen¹, Yi-Feng Chen¹, Ya-Ping Chiu^1,2

¹Graduate School of Advanced Technology, National Taiwan University, Taipei, Taiwan
²Department of Physics, National Taiwan University, Taipei, Taiwan

* Presenter:Yan-Ruei Lin, email:f12222034@ntu.edu.tw

Van der Waals (vdW) heterostructures based on transition metal dichalcogenides (TMDs) provide a versatile platform for next-generation electronic devices, where atomic-scale interactions at TMD–metal contacts critically determine their performance. However, how the crystallographic orientation and atomic geometry of metal contacts govern interfacial coupling in TMDs remains elusive. Here, we combine scanning tunneling microscopy/spectroscopy (STM/S) and density functional theory (DFT) to investigate monolayer MoS₂ deposited on bismuth substrates with distinct surface orientations and twist angles. We reveal that reduced atomic spacing on both Bi(110) and Bi(111) surfaces enables interfacial electronic hybridization extending beyond the topmost atomic layer. This enhanced coupling gives rise to a pronounced in-gap state near the Fermi level in MoS₂/Bi(110), originating from the hybridization between Mo dz²/S pz and Bi pz orbitals. Furthermore, we identify twist-angle–dependent electronic modulation at MoS₂–Bi interfaces, where even minute angular variations markedly tune the coupling strength. These findings establish substrate crystallography and interfacial geometry as powerful design parameters for tailoring electronic coupling in two-dimensional heterostructures, opening pathways toward quantum-engineered contacts and next-generation vdW devices.

Keywords: transition metal dichalcogenides, scanning tunneling microscopy, Bismuth (110)