Raman spectroscopy and conductivity variation of nanocluster carbon thin films grown using a room temperature based cathodic arc process

Nanocluster Carbon (NC) thin films grown at room temperature, using a cathodic arc process, under varying deposition conditions, exhibit interesting electrical and opto-electronic properties. These films are mixed phase material containing both sp² (graphite-like) and sp³ (diamond-like) bonding. A Raman G-peak has been observed between 1585 and 1595 cm ^-1, which indicates graphite-like bonding. A Raman D-peak has been observed between 1355 and 1365 cm^-1, which indicates disorderliness in the carbon structure of the films. The Raman spectra of the films were deconvoluted using Breit-Wigner-Fano line shapes. The Raman parameters, including intensity ratios, peak positions, Full-Width Half Maxima (FWHM) and coupling coefficients obtained from both line shapes, were described and compared with varying Helium partial pressures. The dependence on temperature of the conductivity, showing two regions of electronic transport, is explained based on a thermal-assisted tunneling process. The electrical conductivity varies from 1 × 10^-4 S/cm to 1.66 × 10^-5 S/cm with respect to varying deposition parameters, such as arc current, DC bias and throw distance.