It was recalled that the plasma deposition of nanocrystalline Si thin films was usually performed under a high flux of atomic H and hydrogenated chemical species. The growth mechanisms were investigated here by using the layer-by-layer deposition of dense nanocrystalline Si at 250C via alternating SiH4 and H2 plasmas. Under steady-state conditions, a minimum exposure time to the H plasma was necessary in order to recrystallize the amorphous upper (1 to 8.5nm) layer. It was shown that this critical period was governed by the diffusion time of mobile H through the upper amorphous hydrogenated layer. The crystallization was explained in terms of a H diffusion which led to the formation of nano-voids and broken bonds.

C.Godet, N.Layadi, P.Roca i Cabarrocas: Applied Physics Letters, 1995, 66[23], 3146-8