Low threshold field emission from nitrogen-incorporated carbon nanowalls

Field emission performance of nitrogen-incorporated vertically-aligned graphene layers, so called “carbon nanowalls (CNWs)”, is found to depend upon their electrical conduction properties. The CNW samples with n-type conduction exhibit near-ideal Ohmic contacts with various metals such as Cu, Ti, and Au, regardless of the work function of the metals. The high resistivity CNWs for lower deposition temperatures (TD) show semiconducting behavior in the Arrhenius plots, while the low resistivity CNWs for higher TD show semi-metallic behavior. The emission turn-on field versus TD has a very similar trend to the bulk resistivity versus TD, and is reduced down to about 3 V/μm when the resistivity reaches a minimum (3.0 × 10− 3 Ω cm). The lower turn-on field for semi-metallic CNWs is attributed to an upward shift of the emission level, which is responsible for a decrease in the surface potential barrier height for emission.