Raman imaging on high-quality graphene grown by hot-filament chemical vapor deposition

We report the synthesis of high-quality graphene on Cu foils using hot-filament chemical vapor deposition technique and demonstrate that by suitably varying the CH₄ and H₂ flow rates, one can also obtain hydrogenated graphene. Micro-Raman spectroscopy studies confirm the growth of monolayer graphene as inferred from the intensity ratio of 2D to G peak which is nearly four in unhydrogenated samples. Detailed Raman area mapping confirms the uniform coverage of monolayer graphene. The grown layer is also transferred onto a Si substrate over ~10 × 10 mm sq. area. The present results provide a leap in synthesis technology of high-quality graphene and pave way for scaling up the process.