The effects of the H concentration and of the thermal history upon H-trapping in hydrogenated amorphous material were investigated by analyzing D diffusion profiles. The unexpected results indicated that the number of traps increased with H concentration, while the trap depth increased upon annealing. The H which was equilibrated within the film was associated with traps, while rapidly introduced H was not. The results were consistent with a model of trapping and release from H clusters which nucleated and grew in response to added H. It was proposed that the effective diffusion coefficients for high concentrations of H in amorphous, polycrystalline, or monocrystalline Si were determined by these clusters.

W.B.Jackson, P.V.Santos, C.C.Tsai: Physical Review B, 1993, 47[15], 9993-6