Effect of the target power density on the synthesis and physical properties of sputtered nc-C films

Hydrogen-free nanostructured carbon (nc-C) films were synthesized at various graphite target power densities using a closed field unbalanced magnetron sputtering system (CFUBM). The power density of each graphite target was varied from 10 to 30 W/cm2 in Ar gas atmosphere with a fixed pressure of 0.4 Pa and a substrate bias voltage of−200 V. The aim of this study was to determine the relationship between the microstructure and physical properties of nc-C films as a function of the target power density. The film structures were examined by Raman spectroscopy, X-ray photoelectron spectroscopy and field emission scanning electron microscopy. The physical properties of the nc-C films were evaluated using a nano-indentation tester, a 4-point probe and a residual stress tester. The number of graphitic nano-cluster increased with increasing target power density and a good conductive nanostructured carbon film was obtained. The nc-C film deposited at a target power density of 30 W/cm2 exhibited the minimum electrical resistivity.