Profiling and effusion experiments were performed on post-hydrogenated (deuterated) chemical vapour deposited layers (2 or 0.2µm grain size) in order to study the configurations and stability of the H bonding in polycrystalline undoped diamond. The D was used as a tracer in order to improve the H detection limit. The diamond layers were first annealed at 1200C in order to out-diffuse any H present in the as-grown sample. The samples were then exposed to a radio-frequency or microwave plasma, and the D diffusion profiles were analyzed by means of secondary ion mass spectrometry. For both radio-frequency and microwave plasmas, the diffusion profiles could be explained in terms of trapping at plasma-induced defects near to the surface and/or at intergranular and intragranular defects. The mean free paths of D, and the capture radii of traps were calculated by fitting the D diffusion profiles. These depended upon the grain size. Some chemical vapour deposited layers were obtained by using a CH4+D2 gas mixture, and a D concentration of 3 x 1019/cm3 (originating from the gas) was found in the as-grown samples.

Hydrogen Diffusion and Stability in Polycrystalline CVD Undoped Diamond. D.Ballutaud, F.Jomard, B.Theys, C.Mer, D.Tromson, P.Bergonzo: Diamond and Related Materials, 2001, 10[3-7], 405-10