Selectively 13C-enriched diamond films studied by nuclear magnetic resonance

Abstract

The quality of hot-filament chemical-vapor-deposited diamond films has been quantitatively assessed by 1H and 13C nuclear-magnetic-resonance (NMR) spectroscopy. As the carbon mole fraction increases from 0.053 to 0.074 in the gas phase, film quality in terms of sp2 carbon content, bonding disorder, and spin-lattice relaxation times deteriorates, in agreement with the qualitative results of Raman spectroscopy and scanning electron microscopy. Selective isotopic labeling of the acetone reactant and subsequent 13C NMR analysis shows that the carbonyl carbon of acetone is incorporated into the growing diamond films. Secondary-ion mass spectroscopy reveals that heterogeneous exchange reactions, involving the carbonyl carbon at the tantalum filament, are responsible for this phenomena.