Developments in Nanopatterning of Graphene; Toward Direct Writing

Graphene, with its exceptional electronic, mechanical, and thermal properties, remains a cornerstone material for next-generation nanoelectronics. However, conventional lithographic approaches to graphene patterning are fraught with challenges, including contamination, alignment complexity, and scalability constraints. This review critically examines the evolving landscape of direct-write graphene technologies, focusing on forefront strategies such as focused electron beam-induced deposition (FEBID), polymer-to-graphene (P2G) conversion, focused ion beam (FIB) modification, and laser-assisted graphitisation. These techniques represent a departure from traditional top-down or transfer-based methods by enabling bottom-up, spatially resolved patterning without intermediary masking steps. Particular attention is devoted to the physicochemical mechanisms that underlie electron- and photon-mediated graphitisation, the role of precursor chemistry and substrate interactions, as well as the influence of beam parameters on sp²-carbon content and structural ordering. The review further delineates the limitations intrinsic to current methodologies, including partial graphitisation, resolution fidelity, and hardware constraints, and proposes a roadmap to achieve truly "direct" graphene writing. This includes in situ processing under controlled environments, advanced beam control systems, and the adoption of catalytic and graphitizable precursors. Collectively, this work provides a comprehensive foundation for the rational design of next-generation nanofabrication protocols and underscores the transformative potential of direct-write techniques in enabling scalable, high-fidelity graphene-based devices.