Nicholas Olsen, Sunggun Yoon, Madisen Holbrook, Morgan Thinel, Luke N. Holtzman, Yufeng Liu, Valerie Hsieh, Yiliu Li, David D. Xu, Esteban Rojas‐Gatjens, Dorian Gavilanes, Taketo Handa, Eric A. Arsenault, Chun‐Ying Huang, Yinjie Guo, Cory R. Dean, Katayun Barmak, Abhay N. Pasupathy, James Hone, Xiaoyang Zhu
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.