Study on FN-DLC thin films: (Ⅳ) effect of nitrogen doping on structural properties of films

Nitrogen doped fluorinated diamond-like carbon (FN-DLC) films were deposited on p-type silicon wafers under different deposition conditions. Fourier transform infrared absorption spectrometry (FTIR) shows that the number of C—H bonds decreases with increasing r(r=N2/［N2+CF4+CH4］), but those of C=N, C≡N bonds increase gradually. Gaussian fit results of C1s and N1s in X-ray photoelectron spectra (XPS) show that the β-C3N4 and a-CNx(x=1,2,3) structures have formed in the films. The G band widening and the peak shift to the low wave-number in Raman spectra show that doping of N2 increases the fraction of sp2. Atomic force microscopy (AFM) reveals that the surface morphology of the films becomes smooth due to doping of nitrogen.