Scalable nanoimprint patterning of thin graphitic oxide sheets and in situ reduction

This article presents a scalable technique to precisely deposit and pattern graphitic oxide (GO) flakes onto a SiO₂/Si or glass substrate. A blanket coating of GO was first applied from a colloidal solution onto an amine-functionalized SiO₂ /Si substrate. The amine termination was used to enhance the adhesion of GO sheets to the substrate. A poly(methyl methacrylate) (PMMA) etch mask was patterned via nanoimprint lithography on top of the GO coating. An oxygen plasma etch was then used to remove GO from areas unprotected by the PMMA mask. The PMMA mask was then dissolved by solvent lift-off technique leaving behind GO lines. GO lines down to 250 nm have been demonstrated. Reduction in hydrazine, followed by annealing in hydrogen ambient, increases the conductivity of the patterned GO lines. This technique can enable large-scale fabrication of electronic devices and sensors based on patterned GO sheets.