Journal Article

Disassembling 2D van der Waals crystals into macroscopic monolayers and reassembling into artificial lattices

Zhu, X.-Y., Bai, Yusong, Wang, Jue, Hone, James, Chae, Sang Hoon, Li, Qiuyang, Liu, Fang, Wu, Wenjing

2020

Overview

Although the exfoliation of monolayers of materials such as transition metal dichalcogenides produces high-quality electronic materials with low defect densities, the size of the monolayers is limited to the micrometer scale. Liu et al. modified this method by creating atomically flat gold layers on polymer supports. The strong van der Waals adhesion of the gold layer allowed monolayers to be exfoliated on the centimeter scale. Multilayers could be reassembled to artificial structures, such as a MoSe 2 /WSe 2 single-crystal bilayer with a twist angle chosen to quench intralayer exciton formation. Science , this issue p. 903 A polymer-supported atomically flat gold tape exfoliated centimeter-scale monolayers of transition metal dichalcogenides. Two-dimensional materials from layered van der Waals (vdW) crystals hold great promise for electronic, optoelectronic, and quantum devices, but technological implementation will be hampered by the lack of high-throughput techniques for exfoliating single-crystal monolayers with sufficient size and high quality. Here, we report a facile method to disassemble vdW single crystals layer by layer into monolayers with near-unity yield and with dimensions limited only by bulk crystal sizes. The macroscopic monolayers are comparable in quality to microscopic monolayers from conventional Scotch tape exfoliation. The monolayers can be assembled into macroscopic artificial structures, including transition metal dichalcogenide multilayers with broken inversion symmetry and substantially enhanced nonlinear optical response. This approach takes us one step closer to mass production of macroscopic monolayers and bulk-like artificial materials with controllable properties.

• Publisher: The American Association for the Advancement of Science,American Association for the Advancement of Science (AAAS)
• Subject: Bilayers / Chalcogenides / Crystal lattices / Crystal structure / Crystals / Dismantling / Electronic devices / Electronic materials / Excitons / Exfoliation / Gold / Manufacturing / Mass production / Monolayers / Multilayers / Nonlinear response / Optoelectronic devices / Polymers / Single crystals / Transition metal compounds / Two dimensional materials