Inert Mask Lithography of Edge Narrowed Graphene Nanoribbons Directly Contacted to Metallic Electrodes

Abstract Patterning graphene into strips with nanometer‐scale widths, i.e. graphene nanoribbons, is an effective approach to customize different properties of the material. Narrowing a large sheet of graphene via conventional top‐down approaches meets the intrinsic resolution limitations of lithography. Process residuals as a result of using sticky polymeric templates may also influence the performance of the eventual device, in addition to altering the chemistry of the ribbons. Here, a facile approach for pattering graphene nanoribbons via an inert metallic mask lithography is reported. The masks are prepared by the microtomy of metallic thin films, embedded within polymeric scaffolds and precisely deposited on top of a graphene monolayer. The inertness of the masks allows the precise narrowing of the graphene under different etching environments, permitting the control over the edge chemistry. Remarkably a mild ultrasonication is enough to remove the mask entirely at the end of the process, without leaving any residue. For electronic applications, however, partial removal of the metallic mask using a laser power, in situ realizes a pair of electrodes, hence avoiding the often difficult issue of electrode alignment. The method proposes a simple and direct approach towards the design of chemically tailored, scalable, and electrically connected graphene nanoribbons.