Comparison among XAES, PELS and XPS techniques for evaluation of Sp2 percentage in a-C:H

The ratio R of Sp3 to Sp2 in hydrogenated amorphous carbon (a-C:H) has been evaluated by X-ray Auger electron spectroscopy (XAES), photoelectron energy loss spectroscopy (PELS) and X-ray photoelectron spectroscopy (XPS). Hydrogenated amorphous carbon samples have been deposited by dual ion beam sputtering technique (DIBS). Percentages of Sp2 sites are in the range of 45% to 70% for all analyzed samples. Values measured by XAES are about 10% greater than values measured by PELS and the XPS evaluation appears in agreement with them. Besides, R values seem to be influenced not only by hydrogen contents but even by parameters of deposition (i.e. energy of hydrogen ion beam and growth rate).