1.5 Minute-synthesis of continuous graphene films by chemical vapor deposition on Cu foils rolled in three dimensions

We report a high-productivity chemical vapor deposition (CVD) process of graphene by extending the reaction field to three dimensions (3D) and shortening the CVD time to a few minutes. A large Cu foil (5 × 30 cm²) is rolled up and set in a small reactor (3.4 cm in diameter), and a continuous graphene film is obtained uniformly in a short time (1.5 min) by using C₂H₄ as a more reactive carbon source than the popular CH₄. The graphene transferred onto a quartz glass showed optical transmittances of 94.8–96.7% (550 nm) with sheet resistances of 0.78–1.68 kΩ sq⁻¹ (without doping) and 0.3 kΩ sq⁻¹ (with doping by HNO₃ vapor). Compared with the previous reports for fast and/or large-scale CVD, our method realized similarly high productivity of 100 cm² min⁻¹ based on the CVD time despite of the small reactor, and higher productivity of 0.03 cm²-graphene per cm³-reactor per minute based on the reactor volume and total time for high temperature processing (15 min for heating, 1 min for annealing, and 1.5 min for CVD). The knowledge obtained here on the CVD conditions and packing ratio of Cu foils (0.55 cm² per cm³-reactor) is reusable for designing large-scale graphene production processes.