The diffusivity of As in polycrystalline films was studied using a novel bilayer structure which consisted of a polycrystalline Si layer that was doped in situ with As and deposited onto an undoped polycrystalline Si layer. This technique avoided the complication of structural changes resulting from the ion implantation used in other investigations. The diffusivity was measured at between 700 and 850C and could be described by:

D(cm2/s) = 1 x 101exp[-3.36(eV)/kT]

The average deviation from this equation was less than 20%. The values were about 3 orders of magnitude greater than the intrinsic diffusivity of As in the Si lattice. It was suggested that diffusion occurred along grain boundaries and that certain background impurities in the grain boundaries were responsible for the large variations in data reported in the literature.

Diffusion of Arsenic in Bilayer Polycrystalline Silicon Films. M.Arienzo, Y.Komem, A.E.Michel: Journal of Applied Physics, 1984, 55[2], 365-9