Multi-layers were investigated by using an in situ low-angle X-ray diffraction technique. The temperature-dependent interdiffusivities could be described by an Arrhenius relationship (figure 2):

D (m2/s) = 6.20 x 10-21 exp[-0.37(eV)/kT]

giving a diffusivity of 5.2 x 10-25m2/s at 458K. It was concluded that the extremely small values of the pre-exponential factor, and a clear correlation between the pre-exponential factor and the activation energy for interdiffusion suggested that a collective jump mechanism which involved between 8 and 15 atoms governed interdiffusion in the monolayers.

W.H.Wang, H.Y.Bai, W.K.Wang: Journal of Applied Physics, 1999, 86[8], 4262-6