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 (T_D) show semiconducting behavior in the Arrhenius plots, while the low resistivity CNWs for higher T_D show semi-metallic behavior. The emission turn-on field versus T_D has a very similar trend to the bulk resistivity versus T _D, 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.