Small-angle X-ray scattering and D secondary ion mass spectrometric studies of the microstructure and H dynamics in undoped radio-frequency sputter-deposited, and in undoped and B-doped electron-cyclotron resonance-deposited hydrogenated amorphous samples were described. In radio-frequency sputter-deposited Si1-xCx, with x less than 3at%, the D secondary ion mass spectrometry data yielded a power-law time-dependent H diffusion constant, where the dispersion parameter varied from 0 to about 0.5; from sample to sample. It was temperature-independent at 350 to 475C. The moderate values of the dispersion parameter were consistent with moderate initial nanovoid contents. The values of the activation energy among the various films, for a diffusion length of 100nm, were about 1.7, 1.4 and 0.65eV. The first 2 values were similar to those found in amorphous hydrogenated Si, but the reason for the anomalously low value of 0.65eV was unclear. In undoped electron-cyclotron resonance-deposited samples with 14at%C, the time-dependence exhibited a similar power-law behaviour, but with a dispersion parameter which decreased from 0.3 at 350 and 400C, to 0.1 at 450C. In spite of the high C-content, the behavior of the dispersion parameter was similar to that in amorphous hydrogenated Si at lower temperatures. However, the activation energy was anomalously low (1.0eV). The evolution of the infra-red spectra of radio-frequency sputter-deposited and electron-cyclotron resonance-deposited films showed that, during annealing, the Si-bonded H content decreased relative to the C-bonded H content. This was consistent with the transfer of H from Si- to C-bonded sites, or with H evolution. The B-doping of electron-cyclotron resonance-deposited carbides also reduced the bulk-like Si-bonded H content; thus suggesting that it introduced nanovoids. This was consistent with the observed suppression of the long-range motion of most of the H and D atoms. A small fraction of the H atoms appeared to undergo a rapid diffusion which recalled the rapid diffusion in B-doped amorphous hydrogenated Si.

Microstructure and Hydrogen Dynamics in Hydrogenated Amorphous Silicon Carbides. J.Shinar, R.Shinar, D.L.Williamson, S.Mitra, H.Kavak, V.L.Dalal: Physical Review B, 1999, 60[23], 15875-89