Thermally Activated Gold-Mediated Transition Metal Dichalcogenide Exfoliation and a Unique Gold-Mediated Transfer

Abstract

Layered materials like transition metal dichalcogenides (TMDCs) enable exciting new physics in their 2D limit. Combined with successful demonstrations of 2D transistors and devices, the need for high-quality large-scale monolayers increases. In this light, scalable gold-mediated exfoliations attract broad attention to supersede the traditional scotch tape method as a means for high-quality materials. Gold proved to be suitably adhesive for the exfoliation of several 2D materials, including TMDCs. Previously reported methods rely on a simple press and peel mechanism. However, herein, a gold-mediated exfoliation enabled by low-temperature annealing is presented for the first time. This simple modification potentially increases the range of external conditions under which gold-mediated exfoliations operate in a robust manner. The exfoliation achieves scaling with parent crystal areas, rendering it on par with previously reported methods. On top of that, a unique gold-mediated transfer concept is introduced, where gold is repurposed as a metallic (polymer-free) transfer membrane. The transfer allows the deterministic and clean relocation of the exfoliated monolayers onto technologically relevant substrates like SiO2/Si. The process is benchmarked using MoS2 as the prototypical TMDC and monolayer areas up to ≈80 mm2 are successfully exfoliated and transferred.