Time‐Resolved Observation of Deposition Process of Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films in Pulsed Laser Deposition

Abstract

Optical emission spectroscopy was used to study pulsed laser ablation of graphite in a hydrogen atmosphere wherein ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon (a‐C:H) composite films were grown on heated substrates. Time‐resolved photographs of a plume that expanded from a laser‐irradiation spot toward a substrate were taken using a high‐speed ICCD camera equipped with narrow‐bandpass filters. While the emissions from C atoms and C2 dimers lasted above the laser‐irradiation spot on the target, the emission from C+ ions lasted above the substrate surface for approximately 7 microseconds, although the emission lifetime of species is generally approximately 10 nanoseconds. This implies that C+ ions actively collided with each other above the substrate surface for such a long time. We believe that the keys to UNCD growth in PLD are the supply of highly energetic carbon species at a high density to the substrate and existence of atomic hydrogen during the growth.