By using a combination of chemical lattice imaging and vector pattern recognition, the composition of individual atomic planes across the interface was determined as a function of the annealing temperature. The resultant composition profiles, which directly revealed (with near-atomic resolution) the chemical change across each interface, were analyzed in terms of linear and non-linear diffusion theories in order to deduce the interdiffusion coefficient and the activation energy. It was found that the interdiffusion coefficient was non-linear and was a sensitive function of the depth of the interface below the surface.

Y.Kim, A.Ourmazd, R.D.Feldman: Journal of Vacuum Science and Technology A, 1990, 8[2], 1116-9