Study on Direct Growth of Carbon Nanotubes Induced by Electric Field

In this paper,the electric field is applied in the direct Chemical Vapor Deposition(CVD)growth of CNTs to obtain vertically arranged multi-walled carbon nanotube(MWNT)films on alloy substrates.The diameter of the MWNT is about 50 nm and the length is about 2~3 μm.The crystallinities of the MWNTs are better than those grown without electric field,and the average ratios of Raman spectrum D peak to G peak intensities I_D/I_G are 0.76 and 0.87,respectively.Com-pared with randomly arranged carbon nanotubes,the vertically aligned carbon nanotubes obtained in this work exhibit higher field emission current densities under the same electric field,and the turn-on electric fields are 3.0 V/μm and 3.8 V/μm,respectively.The aligned MWNT emitters presented good emission stability in low emission level,but the dense MWNT distribution result in high electric field shielding effect.Therefore,further attempts to adjust the MWNT spaces will be helpful to increase the emission current density.