Growth of carbon nitride thin films by radio-frequency-plasma-enhanced chemical vapor deposition at low temperatures

In this paper, we report our findings in the deposition of carbon nitride by radio-frequency-plasma-enhanced chemical vapor deposition (RF-PECVD) at temperatures slightly above room temperature (RT) and pressures of 800 mTorr using NH3 and C2H4 as source gases. The variation of the NH3/C2H4 source gas ratio and rf power is shown to affect the N/C ratio and sp(3)/sp(2) ratio in a reproducible manner. An N/C ratio as high as 1.17 has been obtained under optimized growth conditions of NH3/C2H4 ratio of 7.3 and rf power of 90 W. X-ray diffraction (XRD) indicates the presence of microcrystalline carbon nitride in an amorphous CNx matrix with preferred orientation along the (100) direction. X-ray photoelectron microscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) studies show that our assignment of the XPS peaks and FTIR absorption bands are mutually consistent and in good agreement with published data. Both methods of analysis show the increase in the sp(3) component with increase in N incorporation in the film.