Thin Solid Films, Vol.518, No.23, 6915-6920, 2010
Enhanced electron emission from titanium coated multiwalled carbon nanotubes
Enhanced field emission properties and improved crystallinity of titanium (Ti) coated multiwalled carbon nanotubes (MWCNTs), prepared by microwave plasma enhanced chemical vapour deposition have been observed. Ti films of extremely low thicknesses (0.5 nm, 1.0 nm and 1.5 nm) were coated over carbon nanotubes (CNTs) and their field emission behaviour was investigated. The turn on field of Ti coated CNTs was found to be low (similar to 0.8 V/mu m) as compared to pristine CNTs (similar to 1.8 V/mu m). The field enhancement factor for Ti coated CNTs was quite large (similar to 1.14 x 10(4)) as compared to pristine CNTs (similar to 6 x 10(3)). This enhancement in electron emission is attributed to the passivation of defects and improved crystallinity of CNTs Surface morphological and microstructural studies were carried out to investigate the growth of pristine and Ti coated CNTs. It was observed that Ti nanoclusters adsorb on the edges of MWCNTs and increase their crystallinity. This increase is directly correlated with the thickness of Ti film deposited. Micro Raman spectroscopy confirmed the improved crystallanity of Ti coated CNTs. (C) 2010 Elsevier B.V. All rights reserved.
Keywords:Carbon nanotubes;Micro Raman spectroscopy;High resolution transmission electron microscopy;Field emission