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

Soft X-ray emission spectroscopy based on electron microscopy was applied to investigate bonding electron states of amorphous carbon nitride (a-CNx) 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-CNx 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-CNx 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.