Vertically aligned graphene sheets grown on carbon nanotubes

Vertically aligned graphene sheets were grown on carbon nanotubes by microwave-plasma enhanced chemical vapor deposition. Due to their high multistage enhancement and intrinsic low contact resistance, these graphene sheets resulted in good emission property. It was found that the turn-on field was 1.4V/μm, and the threshold-field corresponding to emission current density of 1mA/cm
²
was about 2.9V/μm. The high enhancement factor was attributed to the effects of the high aspect ratio of graphene sheets and the geometry of carbon nanotubes.