Effects of nitrogen content on structure and electrical properties of nitrogen-doped fluorinated diamond-like carbon films

Nitrogen-doped fluorinated diamond-like carbon (FN-DLC) films were prepared on single crystal silicon substrate by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) under different deposited conditions with CF4, CH4 and nitrogen as source gases. The influence of nitrogen content on the structure and electrical properties of the films was studied. The films were investigated in terms of surface morphology, microstructure, chemical composition and electrical properties. Atomic force microscopy (AFM) results revealed that the surface morphology of the films became smooth due to doping nitrogen. Fourier transform infrared absorption spectrometry (FTIR) results showed that amouts of C=N and CN bonds increased gradually with increasing nitrogen partial pressure r (r=p(N2)/p(N2+CF4+CH4)). Gaussian fit results of C 1s and N 1s in X-ray photoelectron spectra (XPS) showed that the incorporation of nitrogen presented mainly in the forms of β-C3N4 and a-CNx (x=1, 2, 3) in the films. The current−voltage (I−V) measurement results showed that the electrical conductivity of the films increased with increasing nitrogen content.