Direct growth of doping-density-controlled hexagonal graphene on SiO ₂ substrate by rapid-heating plasma CVD

A transfer-free method for growing carrier-density-controlled graphene directly on a SiO ₂ substrate has been realized for the first time by rapid-heating plasma chemical vapor deposition (RH-PCVD). Using this method, high-quality single-layer graphene sheets with a hexagonal domain can be selectively grown between a Ni film and a SiO ₂ substrate. Systematic investigations reveal that the relatively thin Ni layer, rapid heating, and plasma CVD are critical to the success of this unique method of graphene growth. By applying this technique, an easy and scalable graphene-based field effect transistor (FET) fabrication is also demonstrated. The electrical transport type of the graphene-based FET can be precisely tuned by adjusting the NH ₃ gas concentration during the RH-PCVD process.