Top-down nanopatterning of layered transition metal dichalcogenide heterostructures*

Nanostructured materials give rise to useful features such as size-dependent properties, interfacial phenomena, and edge effects, allowing optimization for opto-electronics. Although electron beam lithography has been widely used for top-down fabrication of nanostructures, translating this approach to the emerging class of 2D materials has challenges. Direct electron beam exposure on 2D materials can lead to non-reversible damage and degradation of optical and electronic properties. We show that e-beam damage can be significantly reduced on monolayer transition metal dichalcogenides by covering it with a thin hexagonal boron nitride layer. The reduced damage allows direct negative resist lithographic writing of sub-10nm nanostructure fabrication without impairing the monolayer optical and electrical properties.