4. Direct Growth of Graphene and Graphene Nanoribbon on an Insulating Substrate by Rapid-Heating Plasma CVD

A transfer-free method for growing 2D graphene sheets directly on a SiO₂ substrate has been realized by rapid-heating plasma chemical vapor deposition (RH-PCVD). Using this method, high-quality single-layer graphene sheets with hexagonal domain can be selectively grown between a Ni film and a SiO₂ 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, graphene nanoribbon, 1D graphene structure, has also been directly grown on a SiO₂ substrate. Precise control of the site and alignment of narrow (∼23 nm) graphene nanoribbons can be realized by directly converting a nickel nanobar into a graphene nanoribbon using rapid-heating plasma CVD. The nanoribbons grow directly between the source and drain electrodes of a field-effect transistor without any posttreatment and exhibit a clear transport gap (58.5 meV) and a high on/off ratio (>10⁴). The process is scalable and completely compatible with existing semiconductor processes and is expected to allow the integration of graphene nanoribbons with silicon technology.