Low temperature growth of vertically aligned carbon nanofibres in a low frequency inductively coupled plasma reactor

Large area, highly uniform, vertically aligned carbon nanofibres (VACNF) have been grown between 250 to 450°C using a high density, low frequency, inductively coupled plasma source in an Ar/H₂/CH₄ discharge. The dynamic growth process is monitored using an in-situ, high resolution optical emission spectroscope. The growth of VACNFs is carried out on lightly doped silicon (100) substrates, which have been predeposited with nanometer layered Ni/Fe/Mn catalysts. The morphology, crystalline structure and chemical states of the VACNFs are found to have a strong dependence on the growth conditions, in particular on the applied substrate bias and pretreatment of the catalysts. The field emission SEM shows that the CNFs grown with externally applied bias are well aligned and orthogonal to the surface of the substrate. The XRD and Raman spectroscopy analyses suggest that the carbon nanofibres are well graphitized. It is observed that the growth temperature and externally applied bias play a vital role in the transition from carbon nanoparticles to vertically aligned nanofibres. This low temperature and large area growth process offer a great opportunity for the realization of VACNF-based devices.