Macroscopic Transition Metal Dichalcogenide Monolayers from Gold-Tape Exfoliation Retain Intrinsic Properties.

The "gold-tape" exfoliation technique can deterministically exfoliate macroscopic transition metal dichalcogenide (TMD) monolayers from bulk single crystals, overcoming limitations of the widely used "Scotch-tape" method, but concerns over the quality of the large-area monolayers remain. Here we introduce a critical step improving the gold-tape method by eliminating a previously unknown polymer residue layer on the TMD surface. The resulting pristine and millimeter-scale TMD monolayers exhibit defect density, charge carrier mobility, and excitonic properties intrinsic to the parent crystal. Imaging, transport, and spectroscopy on length scales spanning 6 orders of magnitude demonstrate the viability of gold-exfoliated TMD monolayers for the deterministic fabrication of high-performance van der Waals devices, including moiré interfaces.