Abstract
Carbon nanotubes (CNTs) can be understood as one or more graphite sheets rolled up into a seamless cylinder. CNTs have gained much attention and scientific interest due to their unique properties and potential applications since their discovery in 1991. In the present work, we have deposited Ni95Ti5 film using thermal deposition method. Finally, the Ni95Ti5 catalyzed multi wall carbon nanotubes (MWNTs) are grown on silicon substrate using low pressure chemical vapor deposition (LPCVD) method and the electrical transport properties of this MWNTs film are studied over a temperature range (284-4K) to explain the conduction mechanism. We have suggested two types of conduction mechanism for the entire temperature range. For the temperature region (284-220K), the conduction is due to thermally activated process, whereas the conduction takes place via variable range hopping (VRH) for the temperature range of (220-4K). The VRH mechanism changes from three dimensions to two dimensions as we move down to the temperature below 50K. Therefore, the data for the temperature region (220-50K) is plotted for three dimensional variable range hopping (3D VRH) model and the two dimensional variable range hopping (2D VRH) for lower temperature range of (50-4K). These VRH models give a good fit to the experimental data. Using these models, we have calculated various interesting electrical parameters such as activation energy, density of states, hopping distance and hopping energy. Copyright (C) 2009 Zishan Husain Khan et al.