Visualizing the Atomic-scale Origin of Moiré-reconstructed Behavior in twisted 2D semiconductors

Hung-Chang Hsu^1*, Hao-Yu Chen², Yi-Han Lee¹, Hsiang Lee¹, Bo-Hong Wu¹, Yi-Feng Chen², Ming-Yang Li³, Ya-Ping Chiu^1,2

¹Department of Physics, National Taiwan University, Taipei, Taiwan
²Graduate School of Advanced Technology, National Taiwan University, Taipei, Taiwan
³Taiwan Semiconductor Manufacturing Company, Hsinchu, Taiwan
⁴Institute of Physics, Academia Sinica, Taipei, Taiwan

* Presenter:Hung-Chang Hsu, email:hsiuta617@gmail.com

A structural moiré reconstruction occurs in the small-angle twisted bilayer (twBL) of two-dimensional materials. The consequent moiré electronic characteristics create a strong correlation environment for significant physical phenomena dependent on the material intrinsic feature. However, the direct experimental observation on the atomic scale of the structural reconstruction is still not fully understood, hindering our comprehension of the diverse electronic findings through twisted-moiré engineering. In this study, we visualized the atomic structure of each sublayer in twBL transition metal dichalcogenides (twBL-TMDs) on the HOPG substrate using in-situ scanning tunneling microscopy/spectroscopy and non-contact atomic force microscopy. The results revealed that the lattice displacement occurs only on the sublayer attached to the HOPG substrate, still remaining to conform to the stacking configuration of reconstructed rhombic-stacked twBL-TMDs. Our imaging technique provides direct information on moiré reconstruction under twist-stacked engineering and opens up innovative avenues to uncover the hidden mechanism of the reconstruction process.

Keywords: moiré, scanning tunneling microscopy, transition metal dichalcogenide