Electrical transport in Ni-catalysed multi-walled carbon nanotubes

Abstract

Low pressure chemical deposition method (LPCVD) is used to synthesise the Ni-catalysed carbon nanotubes (CNTs). These CNTs are grown on supported catalyst film of Ni nanoparticles by the catalytic decomposition of acetylene at 700°C and at a chamber pressure of 10 Torr. We have used field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) to study the morphology of the catalyst film of Ni as well as the CNTs. The standard four probe method is used for electrical transport measurements of these multi-walled carbon nanotubes (MWNTs) over the temperature range of 200-4.2 K. From these results, it is found that the variable range hopping (VRH) is responsible for the transport of carriers over the entire temperature range of 200-4.2 K. For the temperature range (200-100 K), three-dimensional VRH is suggested, while two-dimensional VRH is observed for the temperature range (100-4.2 K).