title: Electrical and Raman spectroscopic studies of vertically aligned multi-walled carbon nanotubes.
abstract: Microwave plasma enhanced chemical vapour deposition (MPECVD) was used for the production of carbon nanotubes. Vertically aligned multi-walled carbon nanotubes (MWCNTs) were grown on silicon substrates coated with cobalt thin films of thickness ranging from 0.5 nm to 3 nm. Prior to the nanotube growth the catalyst were treated with N2 plasma for 5-10 minutes that break the films into small nanoparticles which favour the growth of nanotubes. The CNTs were grown at a substrate temperature of 700 degrees C for 5, 10 and 15 minutes. The height of the CNT films ranging from 10 microm-30 microm indicating that the initial growth rate of the CNTs are very high at a rate of approximately 100 nm/sec. Electrical resistivity of the above samples was evaluated from I-V measurements. The activation energy (E(a)) was also calculated from the temperature dependent studies and it was found that the E(a) lies in the range of 15-35 meV. Raman spectroscopy was used to identify the quality of the nanotubes.
authors.affiliation: Nanotechnology and Integrated Bio-Engineering Centre, School of Electrical and Mechanical Engineering, University of Ulster, Newtownabbey BT37 OQB, UK.
authors.forename: Ashish
authors.initials: A
authors.lastname: Mathur
authors.forename: Mark
authors.initials: M
authors.lastname: Tweedie
authors.forename: Susanta Sinha
authors.initials: SS
authors.lastname: Roy
authors.forename: P D
authors.initials: PD
authors.lastname: Maguire
authors.forename: James A
authors.initials: JA
authors.lastname: McLaughlin
mesh_terms: D003460:Crystallization / Q000379:methods*; D004553:Electric Conductivity; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D036103:Nanotechnology / Q000379:methods*; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013499:Surface Properties
chemical_list: D046911:Macromolecular Substances; D037742:Nanotubes, Carbon