Soft X-ray emission spectroscopy study of characteristic bonding states and its distribution of amorphous carbon-nitride (a-CN_x) films

Soft X-ray emission spectroscopy based on electron microscopy was applied to investigate bonding electron states of amorphous carbon nitride (a-CN_x) films with different nitrogen contents of x. Carbon K-emission spectrum showed characteristic intensity distribution of not only sp² bonding but also sp³ bonding. The a-CN_x film with lager x, which has a larger macroscopic electric resistivity, shows a larger content of the carbon sp³: C-C bonding signal. Furthermore, the dependence of spectral intensity distribution on x suggests the presence of sp²: C-N and sp³: C-N bonding. Those results show that the relation between macroscopic electrical resistivity of a-CN_x film and its nitrogen content is because of the decrease of sp²: C-C bonding and the formation of sp²: C-N and sp³: C-C and C-N bonding conformation induced by an introduction of nitrogen atoms. Spatial variation of a signal ratio of sp³/sp² was visualized and was confirmed as a relation between sp³ boding amount and nitrogen content x.