Suppression of graphene nucleation by plasma treatment of Cu foil for the rapid growth of large-size single-crystal graphene

Chemical vapor deposition (CVD) method generally used for the fabrication of single-crystal graphene is still imperfect in the suppression of nucleation density, which is detrimental to the domain size of single-crystal graphene to a great extent. Herein, we have successfully developed a new strategy to realize the controllable nucleation by the plasma treatment of Cu foil, and carry out the rapid growth of single-crystal graphene, combined with the program heating and concentration gradient growth method during the CVD-grown stage. The plasma treatment can effectively remove impurities of Cu foil surface, which reduces the active sites for single-crystal graphene nucleation. Meanwhile, CuO nanoparticles are formed on the Cu foil surface by the plasma treatment, which can be reduced and produce oxygen after annealing at high temperature in H ₂ atmosphere to promote the rapid growth of graphene and suppress graphene nucleation. Eventually, we have achieved the synthesis of hexagon-shaped single-crystal graphene with the low defects, large-size of ∼5 mm, fast growth rate of 2.5 mm h ⁻¹ , high uniformity (monolayer coverage of ≥90%) and high field-effect mobility of ≥12,500 cm ² V ⁻¹ s ⁻¹ . Our work provides a facile and effective method for the fabrication of large-size single-crystal graphene, paving the way towards future potential applications of single-crystal graphene in the industrial level.