Carbon films embedded by nickel nanoparticles: The effect of deposition time on Berthelot-type hopping conduction parameters

Abstract.

In this paper, the electrical conductivity of carbon films embedded by nickel nanoparticles at different deposition times 50, 90, 180 and 600 s over a temperature range from 50 to 500 K was studied. The conductivity data in the temperature range $T > 300$ K shows the extended state conduction mechanism. The tunneling through a thermally vibrating barrier in the temperature range 50-150 K is described by the Berthelot-type conduction mechanism. It can be seen that the films deposited at 180 s have maximum conductivity and the Berthelot temperature is about 53.5 K. Due to the vibrations of Ni ions in the tetrahedral, sites the extents of the carrier wave function are lower than in the octahedral complexes sites which have maximum values of about $2.16 \times 10^{-7}$ cm and $1.85 \times 10^{-7}$ cm in the octahedral-metal stretching vibrations and intrinsic stretching vibrations of the metal ions at the tetrahedral site, respectively. On the other hand, the average distance between the sites in both vibrations at 180 s deposition modes have minimum values of $2.02 \times 10^{-7}$ cm and $1.72 \times 10^{-7}$ cm.