A STUDY OF THE CHEMICAL BONDING AND MICROSTRUCTURE OF ION BEAM-DEPOSITED CNX FILMS INCLUDING AN XPS C-1S PEAK SIMULATION

The chemical bonding and microstructure of dual ion beam-deposited CN, films with nitrogen contents in the range 20-33 at.% have been examin ed by Fourier transform infrared spectroscopy (FTIR) and x-ray photoel ectron spectroscopy (XPS). The FTIR spectra together with other publis hed data have been used to construct a model microstructure of the CNx films. The XPS N Is peak is composed of two components corresponding to N-sp(2) C and N-sp(3) C bonds. Using the quantified N Is data and m aking certain assumptions, the model microstructure has been used as t he basis of a C Is peak simulation in which nine C components have bee n combined. At an N content of 20 at.% the simulation agrees wed with the experimentally recorded XPS C Is peak. The FTIR spectra, XPS N Is peak shape and C Is peak simulations support a microstructure of N sub stitution into an amorphous sp(2)/sp(3) hybridized carbon structure. A bove an N content of similar to 20%, a new (nitrile-like) chemical for m also emerges in the material, its abundance increasing with N conten t. It is proposed that this new structure occurs due to the presence, in the surface region of the condensing film, of C = N dimers, which a re formed when a C atom is surrounded by many N atoms. This molecule b ecomes trapped in the material and bonds to atoms at neighbouring site s. (C) 1997 by John Wiley & Sons, Ltd.