Measurements of the contact potential difference were made before and after diffusion annealing, and were used to estimate the diffusivity of Al on clean (111) surfaces of single crystals of n-type material. It was found that, at 400 to 700C, the surface diffusivity parallel to the surface could be described by:

D (cm2/s) = 1.0 x 10-1 exp[-0.7(eV)/kT]

B.A.Nesterenko, V.A.Zrazhevskii, V.T.Rozumnyuk: Fizika Tverdogo Tela, 1978, 20[6], 1901-3