Fabrication of vertically aligned carbon nanotubes–zinc oxide nanocomposites and their field electron emission enhancement

Abstract

Systematic investigation on the fabrications of vertically aligned carbon nanotubes (VACNTs) and zinc oxide (ZnO) nanocomposites for two different configurations were performed to enhance the field electron emission (FEE) performance of the VACNTs synthesised from waste chicken fat. FEE tests demonstrated improvement with the addition of ZnO nanostructures under the VACNT array, where the emission current increased from 212.85 to 259.80μAcm−2, while the turn-on field reduced from 2.66 to 1.60Vμm−1. Meanwhile, the growth of ZnO nanostructures on top of the VACNTs array resulted in a tremendous increase in emission current of up to 2090.00μAcm−2 and a decrease in the turn-on field to 0.49Vμm−1. The difference in the FEE improvement by different composite configuration reflects the significant role of the composite order. The improvement of FEE is influenced by the geometrical shape of the emitters as well as tunnelling effect of electrons through the structure of nanocomposite.