Near-Edge X-ray Absorption Fine-Structure Spectroscopic Study on Nitrogen-Doped Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films Prepared by Pulsed Laser Deposition

Nitrogen-doped ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon (a-C: H) composite films, which possessed n-type conduction with enhanced electrical conductivity, were prepared by pulsed laser deposition. The film doped with a nitrogen content of 7.9 at.% possessed enhanced electrical conductivity of 18 Omega(-1).cm(-1) at 300 K. The near-edge X-ray absorption fine-structure (NEXAFS) measurement indicated the appearance of additional peaks due to pi* C=N, sigma* C=N, and sigma* C-N bonds compared with the spectra of undoped films. The sp(2) bonding fraction estimated from the NEXAFS spectra increased with the nitrogen content. The enhanced electrical conductivity is probably due to the formation of additional pi* and sigma* states and the enhancement in the sp(2) bonding fraction. (C) 2011 The Japan Society of Applied Physics