Effect of Nickel Distributions Embedded in Amorphous Carbon Films on Transport Properties

Electrical properties of C/Ni films are studied using four mosaic targets made of pure graphite and stripes of nickel with the surface areas of 1.78, 3.21, 3.92 and 4.64%. The conductivity data in the temperature range of 400–500 K shows the extended state conduction. The conductivity data in the temperature range of 150–300 K shows the multi-phonon hopping conduction. The Berthelot-type conduction dominates in the temperature range of 50–150 K. The conductivity of the films in the temperature range about T < 50 K is described in terms of variable-range hopping conduction. In low temperatures, the localized density of state around Fermi level N(E_\rm F) for the film deposition with 3.92% nickel has a maximum value of about 56.2\times10^17 cm^-3eV^-1 with the minimum average hopping distance of about 3.43\times10^-6 cm.