The tracer diffusion of H was studied in amorphous Si3N4:H films which were produced by radio-frequency magnetron reactive sputtering. The diffusion experiments were carried out at 700 to 1000C, with ion-implanted D isotopes. Secondary ion mass spectrometry was used for depth profile analysis. It was noted that, while a considerable part of the tracer was immobilized due to the interaction with the implantation damage, the other part migrated freely into the film; from which the diffusivities were extracted. These diffusivities coincided with those obtained from a control experiment with a gas exchange technique, demonstrating that the implantation damage had no significant influence upon the determination of the correct diffusivities themselves. The 2H transport could be described by the concept of trap-limited diffusion, where the tracer atoms were temporarily trapped by intrinsic film defects; presumed to be N dangling bonds. For the present case of a considerably high dissociation rate of trapped H, effective diffusivities were derived which obeyed an Arrhenius behaviour,

D (m2/s) = 5 x 10-4 exp[-3.4(eV)/kT]

The effect upon diffusion, of pre-annealing the films prior to diffusion in N, and the possible structural rearrangements which were involved - as well as charging the films with up to 2.6at%H, was analysed.

The Diffusion of Ion-Implanted Hydrogen in Amorphous Si3N4:H Films. H.Schmidt, W.Gruber, G.Borchardt, M.Bruns, M.Rudolphi, H.Baumann: Journal of Physics - Condensed Matter, 2004, 16[24], 4233-44