Characterization and Field Emission Studies of Uniformly Distributed Multi-Walled Carbon Nanotubes (MWCNTs) Film Grown by Low-pressure Chemical Vapour Deposition (LPCVD)

摘要

Carbon nanotubes are synthesized by Low Pressure Chemical Vapor Deposition (LPCVD) system using NH_3:C_2H_2:H_2 gas mixtures on iron coated silicon substrate. The iron catalyst was coated on silicon using RF-sputtering method. The growth temperature was kept at 600℃ and growth time was 10 mins. The carbon nanotubes are found to have diameters ranging from 50 to 80 nm and length of up to a few tens of microns. Raman spectra indicate that the CNTs are highly graphitized and several peaks are also found at low frequency range from 100 cm~(-1) to 500 cm~(-1), which are assigned to the radial breathing mode (RBM) which is the characteristic of single wall carbon nanotubes. Therefore, this sample also contains single walled carbon nanotubes also. The carbon nanotubes showed a turn-on field of 2.63 V/μm and the maximum current density of 2 mA/cm~2. The field enhancement factor was calculated to be 3.941 × 10~3 for as grown carbon nanotubes. The carbon nanotubes grown at this lower temperature show good field emission and are suitable for device applications.