Electron paramagnetic resonance and infra-red absorption studies were made of as-grown and annealed free-standing polycrystalline films. In all of the chemical vapor-deposited films which were investigated, an electron paramagnetic resonance was observed at g = 2.0028. A comparison of the local and bulk concentrations indicated that these centers were inhomogeneously distributed within the films, whereas the single substitutional N centers were homogeneously distributed. The strength of the total electron paramagnetic resonance absorption at g = 2.0028 could be correlated with the total infra-red absorption in the CH region. Upon annealing to 1900K in vacuum, the intensity of the resonance at g = 2.0028 decreased significantly in magnitude, and narrowed slightly. During this treatment, the sharp infra-red absorption line at 2820/cm increased and then decreased in intensity but there were no other significant changes in the infra-red absorption. The results suggested that the dangling bonds which were responsible for the g = 2.0028 electron paramagnetic resonance absorption were not located in the lattice but were found at grain boundaries or in intergranular material. They were compensated during annealing, when H at grain boundaries or in intergranular material became mobile. New and unidentified electron paramagnetic resonance centers were produced when samples were annealed in vacuum above 1800K. It was concluded that the g = 2.0028 center was an unpaired electron that was localized in a C dangling bond. Some of these dangling bonds had H atoms about 0.2nm away. The change in the CH infra-red absorption during annealing indicated that H at internal surfaces was mobile at temperatures above about 1600K. It was proposed that, upon annealing, the g = 2.0028 dangling bond center was terminated by H.

D.F.Talbot-Ponsonby, M.E.Newton, J.M.Baker, G.A.Scarsbrook, R.S.Sussmann, J.R.Brandon, C.N.Dodge: Materials Science Forum, 1997, 239-241, 111-4