Electron field emission properties of carbon nanoflakes prepared by RF sputtering

Carbon nanoflakes (CNFs) with corrugated geometry were synthesized using RF sputtering process with Ar/CH4 gas mixture. Transmission electron microscopic examination reveals that the introduction of H2 in sputtering chamber leads to the preferential etching of amorphous carbons, while maintaining integrity for the nano-crystalline phases. The proportion of nano-sized crystalline clusters is thus increased, which improved the electron field emission (EFE) properties of the materials, viz. with turn-on field of E0 = 6.22 V/μm and FEE current density of Je = 90.1 μA/cm2 at 11.0 V/μm. The cathodes made of screen printing of CNFs-Ag paste exhibit even better EFE properties than the as-deposited CNFs. The EFE of the CNFs cathodes can be turned on at E0 = 5.71 V/μm, achieving J0 = 340.1 μA/cm2 at 11.0 V/μm applied field. These results showed that the CNFs are inheritantly more robust in device fabrication process than the other carbon materials and thus possess better potential for electron field emitter applications.