Near-edge x-ray absorption fine structure of ultrananocrystalline diamond/hydrogenated amorphous carbon films prepared by pulsed laser deposition

The atomic bonding configuration of ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon (a-C:H) films prepared by pulsed laser ablation of graphite in a hydrogen atmosphere was examined by near-edge X-ray absorption fine structure spectroscopy. The measured spectra were decomposed with simple component spectra, and they were analyzed in detail. As compared to the a-C:H films deposited at room substrate-temperature, the UNCD/a-C:H and nonhydrogenated amorphous carbon (a-C) films deposited at a substrate- temperature of 550 °C exhibited enhanced and CC peaks. At the elevated substrate-temperature, the and CC bonds formation is enhanced while the C-H and C-C bonds formation is suppressed. The UNCD/a-C:H film showed a larger C-C peak than the a-C film deposited at the same elevated substrate-temperature in vacuum. We believe that the intense C-C peak is evidently responsible for UNCD crystallites existence in the film.