Scratching Lithography: In Situ Mechanical Exfoliation of van der Waals Materials for Direct-Write Circuits.

Ever since the discovery of graphene via mechanical exfoliation of graphite, 2D nanomaterials have garnered wide interest for high-performance electronics. Mechanical exfoliation of van der Waals (vdW) layered materials produces nearly perfect 2D nanomaterials, yet their application in electronics is impeded by the low yield and random orientation of the resulting flakes. In this work, we developed a technique termed "scratching lithography", which enables in situ exfoliation and patterning of vdW layered materials for direct writing of functional circuits. Scratching lithography employs a probe to scratch an insulating composite film composed of vdW layered materials (showcased by graphite) dispersed in an insulative matrix, during which the embedded layered materials are mechanically delaminated along the probe's trajectory to form pre-designed functional circuits. The functionality of these patterns can be tailored by tuning the composition of the precursor film and the scratching parameters. As a proof of concept, we showcased applications of scratching lithography with customizable, erasable infrared and electroluminescent displays. Additionally, we demonstrated the technique's applicability to other vdW layered materials, including h-BN, MoS2, and WS2. Given its versatility, adaptability, and accessibility, scratching lithography holds potential for the application of electronic devices based on 2D nanomaterials from vdW layered materials.