Influence of surface roughness on field emission of electrons from carbon nanotube films

Electron field emission properties of a nanotube film are influenced not only by a field enhancement factor of carbon nanotubes (CNTs) beta(CNT) but also by that of film morphology beta(P). A simple method to separate beta(P), and beta(CNT) is proposed by using their different dependences on the cathode-anode distance. Analyses conducted for CNT emitters with rough surface exhibit that beta(P) ranges from 1 to approximately 4.5. The separated beta(CNT) values are in good agreement with the CNT geometries observed by a scanning electron microscope. Variation in beta(P)-values is ascribed to the surface roughness of the CNT films.