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CuO nanowires were grown on brown-oxide-coated Cu films on Si substrates by conductive heating in air and their field emission characteristics were investigated. High resolution scanning electron microscopy showed that the CuO nanowires grew perpendicularly to the substrate, and their length and radius could be controlled by varying heating temperature and time. It was found that the lengths of the CuO nanowires were saturated to a certain point with respect to the heating temperature, and the increasing heating time increased the uniformity of the CuO nanowires in length. The field emission characteristics were strongly affected by the formation of the brown-oxide layer and the morphologies of the CuO nanowires governed by heating temperature and time.

The triboelectricity method uses no adhesives but it induced by the difference of triboelectric series between materials can vertically align the carbon nanotube (CNT) emitters. CNTs are attached on a silicon wafer by dip-coating method, and then vertically aligned by the triboelectricity. The field emission property is enhanced up to 270 mA/cm 2 at 4 V/mm after the activation of the emitters but no emission is observed at the same electric field before activation. The triboelectricity method avoids inevitable contamination due to the adhesives of taping method and is suitable for the conventional fabrication process which uses indirect-attachment method of CNTs.

The present study adopts proton irradiation to solve the problems, such as performance degradation due to outgassing and weak adhesion, of a carbon nanotube (CNT) field emitter fabricated by the indirect coating method. The protons collide against the CNT layer and the copper film, and results in thinning out of the CNTs and particle migration of the copper constituents. This process reduces the turn-on field and increases the lifetime of CNT emitters, respectively. Numerical simulations have been performed to understand the results from experiments by using a software, SRIM 2008.

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