Structural investigation of two carbon nitride solids produced by cathodic arc deposition and nitrogen implantation

Abstract

Carbon nitride materials have been the focus of research efforts worldwide. Most materials studied have been amorphous, with only a few groups claiming to have found a crystalline material. We investigate the structure of amorphous carbon nitride solids produced by two different techniques: cathodic arc deposition and high dose nitrogen implantation of glassy carbon. Transmission electron microscopy, electron energy loss spectroscopy, energy filtered electron diffraction, Rutherford backscattering, infrared, and Raman spectroscopy are all used to derive structural information. It was found that the carbon nitride materials prepared by both techniques have similar structures and [N]/[C] ratios (0.3). The materials appear to have a primarily sp2 bonded carbon structure with a smaller bond length than found in amorphous carbon. This is explained by nitrogen substituting into ‘‘rings’’ to a saturation level of about one nitrogen per three carbon atoms. We have found no evidence for a C3N4 crystalline structure, nor any amorphous derivative of it.