Nonmetal—Metal transition in carbon films embedded by Ni nanoparticles: The temperature coefficient of resistivity (TCR), Raman spectra and surface morphology

Abstract

In this paper, carbon films embedded by Ni nanoparticles were deposited on glass substrates. Films using four mosaic targets made of carbon and nickel with Ni surface areas 1.78, 3.21, 3.92 and 4.64% are made. With increasing Ni content in these films a nonmetal–metal transition especially above room temperature region is observed. This transition is explainable by electrical measurements in temperature range 15–500K. With increasing Ni surface areas from 1.87 to 4.64%, Ni content of films increases from59.68 to 92.89%. The electrical conductivity of dielectric films was explained by tunneling effect. Activation tunneling energy that was obtained from temperature dependence of electrical resistivity correlates both with G and D peaks of Raman spectra and depend on Ni content of films. With increasing Ni surface areas from1.78 to 3.92% due to increasing graphen like carbon, a nonmetal–metal and from 3.92 to 4.64% due to increasing amorphous carbon interconnections of Ni nanoparticles, a peculiar effect of metallic to nonmetallic state occurs. The RMS roughness of films in 3.92% has minimum value about 0.54nm.