The migration of ion-implanted As in polycrystalline films (210-510nm) was studied, at 750 to 950C, by using Rutherford back-scattering methods. The form of the concentration profiles was governed by the combined effects of a low diffusivity in the bulk material and a higher diffusivity in the grain boundaries. The latter was independent of the concentration and was governed by an activation energy of 3.9eV. This was similar to the value for low As concentrations in single crystals. The results could be described by:

D (cm2/s) = 8.6 x 104 exp[-3.9(eV)/kT]

These values were some 4 orders of magnitude higher than those for single crystals, while the diffusivity in the bulk of the grains was the same as that in single crystals.

B.Swaminathan, K.C.Saraswat, R.W.Dutton, T.I.Kamins: Applied Physics Letters, 1982, 40[9], 795-8