We report the field emission from carbon nanofibers (CNFs) grown directly on cylindrical copper by a simple pyrolysis technique. The turn-on field is 0.17 V/μm and the emission current density is 0.9 mA/cm2 at 0.35 V/μm. The emission current is stable at a field of 0.35 V/μm and 6.5×10−6 Torr. The excellent field emission behavior is attributed to the sp2 phase in CNFs and the stable emission is due to the direct growth. The direct growth on cylindrical cathode is advantageous for field emission.

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The influence of concentration and size of sp 2 cluster on the transport properties and electron field emissions of amorphous carbon films have been investigated. The observed insulating to metallic behaviour from reduced activation energy derived from transport measurement and threshold field for electron emission of a-C films can be explained in terms of improvements in the connectivity between sp 2 clusters. The connectivity is resulted by the cluster concentration and size. The concentration and size of sp 2 content cluster is regulated by the coalescence of carbon globules into clusters, which evolves with deposition conditions.

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