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

Abstract

This work measures the C and O K-edge x-ray absorption near-edge structure (XANES) spectraof hydrogenated amorphous carbon (a-C:H) films deposited at various baking temperaturesTb (Tb = 300–500 °C at50 °C). TheC–H σ* peak relatedto the content of the sp2 graphite-like bonding in the C K-edge spectra was found to yield to theC–H π* peakrelated to the sp3 diamond-like bonding at high temperature(500 °C). We find that theintensities of both the sp2 and sp3 features in the C K-edge XANES spectra decrease with increase ofTb, which suggests an increase of the defect concentration withTb. The intensities of the O K-edge XANES spectra are found to decrease with increase ofTb, whichsuggests thermally induced decomposition of carbonyl contaminants on the surface. The elementalanalysis C/O (or O/C) ratio was obtained from XPS spectra and indicates that films are not hydrogenatedamorphous carbon but rather oxyhydrogenated amorphous carbon thin films.