X-ray absorption spectroscopy (XAS) study of dip deposited a-C:H(OH) thin films

This work measures the C and O K-edge x-ray absorption near-edge structure (XANES) spectra of hydrogenated amorphous carbon (a-C:H) films deposited at various baking temperatures T-b (T-b = 300-500 degreesC at 50 degreesC). The C-H sigma* peak related to the content of the sp(2) graphite-like bonding in the C K-edge spectra was found to yield to the C-H pi* peak related to the sp(3) diamond-like bonding at high temperature (500 degreesC). We find that the intensities of both the Sp(2) and sp(3) features in the C K-edge XANES spectra decrease with increase of Tb, which suggests an increase of the defect concentration with T-b. The intensities of the O K-edge XANES spectra are found to decrease with increase of T-b, which suggests thermally induced decomposition of carbonyl contaminants on the surface. The elemental analysis C/O (or O/C) ratio was obtained from XPS spectra and indicates that films are not hydrogenated amorphous carbon but rather oxyhydrogenated amorphous carbon thin films.