Growth of large graphene single crystal inside a restricted chamber by chemical vapor deposition

Scalable large graphene single crystals have been synthesized by using a backward faced quartz cuvette in a conventional tube furnace. The effect of the restricted chamber in controlling the graphene single crystal growth has been systematically studied by considering the influence of the flow rate and ratio of H₂ and CH₄ experimentally. Numerical simulations were performed to uncover the underlying mechanism. The convection of CH₄ was substantially suppressed inside the cuvette due to the blocking effect by the close-end geometry. The diffusivity of CH₄ is much lower than that of H₂, resulting in a slow transportation of CH₄ as well. By using the specific experimental parameters, the mass ratio of H₂ and CH₄ increased about 3 times inside the cuvette, leading to preferential growth of graphene single crystals, as observed in our experiments. Meanwhile, the growth of a second layer can be suppressed by the slower feeding of CH₄ than H₂. Based on these results, we believe that setup of our restricted chamber can provide another growth approach for scalable graphene single crystals and its analysis can help understand more growth dynamics of graphene single crystal inside other irregular CVD conditions such as rolled-up and enclosed Cu foils.