Synthesis and field emission properties of nanocrystalline diamond/carbon nanowall composite films

Nanostructured composite films consisting of almost vertically aligned graphene layers, so-called "carbon nanowalls" (CNWs), and nanocrystalline diamond films are prepared by plasma-enhanced chemical vapor deposition. The space between the walls for the composite films is widened compared to simple CNWs by interception of in-plane continuity of the wall structures. The nucleation density of diamond is responsible for the spacing and arrangement of the walls. Field emission measurements show that the composite films have lower turn-on fields (∼1 V/μm) and larger field enhancement factors (∼4000) than simple CNWs. The results indicate that electric field screening between neighboring walls is well suppressed.