Electronic and bonding structures of amorphous Si-C-N thin films by x-ray absorption spectroscopy

X-ray absorption near edge structure (XANES) spectra of hard amorphous a-Si-C-N thin films with various compositions were measured at the C and N K-edge using sample drain current and fluorescent modes. The C K-edge XANES spectra of a-Si-C-N contain a relatively large 1s --> pi* peak, indicating that a substantial percentage of carbon atoms in the a-Si-C-N films have sp(2) or graphite-like bonding. Both the observed sp(2) intensity and the Young's modulus decrease with an increase in the carbon content. For N K-edge XANES spectra of the a-Si-C-N films we find the emergence of a sharp peak near the threshold when the carbon content is larger than between 9% and 36%, which indicates that carbon and nitrogen atoms tend to form local graphitic carbon nitride. (C) 2001 American Institute of Physics.