Preparation and characterization of RF-PECVD deposited films containing β-C 3NN 4 microcrystallites

Abstract

An attempt has been made to prepare crystalline β-C 3NN 4 using a PECVD (plasma enhanced chemical vapor deposition) process in which the nitrogen gas fraction was varied to determine the possible range for the formation of the crystalline β-C 3NN 4 phase. The cross-sectional morphology of the deposited films was observed using SEM (scanning electron miscoscopy). Chemical compositions and chemical states of elements in the deposited films were analyzed using XPS (X-ray photoelectron spectroscopy). XRD (X-ray diffraction) and (transmission electron microscopy) were used to characterize the film structure. Experimental results show that films containing β-C 3NN 4 microcrystallites can be prepared following the PECVD process. The coexistence of C-N and C=N bonding were confirmed. Nitrogen concentration of the deposited films increases with an increasing N 2 gas fraction; it depresses the formation of “disordered” and “graphitic” phase and favors the formation of C-N bonding, and as a result enhances the growth of β-C 3NN 4 microcrystallites. This work demonstrates that the carbon nitride films deposited by PECVD method may achieve the same results obtained by high-energy input processes.