Near-Edge X-Ray Absorption Fine Structure of Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Films Prepared by Pulsed Laser Deposition

摘要

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 π~* and σ~*C= C peaks. At the elevated substrate-temperature, the π~* and σ~* C bonds formation is enhanced while the σ~*C–H and σ~* C–C bonds formation is suppressed. The UNCD/a-C:H film showed a larger σ~* C–C peak than the a-C film deposited at the same elevated substrate-temperature in vacuum. We believe that the intense σ~*C–C peak is evidently responsible for UNCD crystallites existence in the film.