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

Abstract

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 ≡ 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.