Carbonaceous field effect transistor with graphene and diamondlike carbon

A carbonaceous field effect transistor, designated as a 'DLC-GFET', consisting of a graphene channel and a diamondlike carbon (DLC) top-gate dielectric film was fabricated. A DLC film was formed 'directly' onto the graphene channel using our original photoemission-assisted plasma-enhanced chemical vapor deposition (PA-CVD) without forming complex passivation interlayers. The DLC-GFET exhibits clear ambipolar characteristics with a slightly positive shift of the neutral points (Dirac voltages). The Raman analysis suggests that the electrical characteristics are due to unintentional hole doping from the DLC film into the graphene channel. The maximum transconductances per unit device width in the n-channel and the p-channel modes (g _mn,max and g _mp,max) are 14.6 mS/mm and 8.8 mS/mm, respectively, with a gate thickness of 48 nm and a gate length of 5 μm. Formation of the DLC top-gate does not cause obvious damage to the graphene channel. Hence, the PA-CVD method is suitable to form gate dielectrics onto graphene.