Directed exfoliating and ordered stacking of transition-metal-dichalcogenides

TL;DR

This paper introduces a novel exfoliation method that directly controls lattice orientation in transition-metal-dichalcogenides, enabling precise stacking configurations and improving the quality and scalability of 2D materials for advanced quantum studies.

Contribution

A new exfoliation technique utilizing gold favor epitaxy allows direct control of lattice orientation, enhancing the efficiency of stacking order engineering in 2D materials.

Findings

Achieved high-quality, large-size monolayers with controlled stacking configurations.

Demonstrated direct formation of hexagonal and rhombohedral bilayer structures.

Supported the mechanism with optical spectroscopy, electron diffraction, and ARPES analysis.

Abstract

Two-dimensional van der Waals crystals arise limitless scope for designing novel combinations of physical properties via controlling the stacking order or twist angle of individual layers. Lattice orientation between stacked monolayers is significant not only for the engineering symmetry breaking but also for the study of many-body quantum phases and band topology. So far the state-of-art exfoliation approaches focusing on achievements of quality, size, yield, and scalability while lacking sufficient information on lattice orientation. Consequently, interlayer alignment is usually determined by later experiments, such as second harmonic generation spectroscopy, which increased the number of trials and errors for a designed artificial ordering and hampered the efficiency of systematic study. Herein, we report a lattice orientation distinguishable exfoliation method via gold favor epitaxy along the specific atomic step edges, meanwhile, fulfill requirements of high-quality, large-size, and high-yield of monolayers. Hexagonal- and rhombohedral-stacking configurations of bilayer transition metal dichalcogenides are built directly at once result of foreseeing the lattice orientation. Optical spectroscopy, electron diffraction, and angle-resolved photoemission spectroscopy are used to study crystals quality, symmetric breaking, and band tuning, which supports the exfoliating mechanism we proposed. This strategy shows the ability for facilitates the development of ordering stacking especially for multilayers assembling in the future.