Nuclear analysis and ion-beam etching were used to study the diffusion at 400 to 700C. The concentration profiles were complex and comprised 3 regions. The data were interpreted as being the result of the superposition of various diffusion mechanisms. In one case, the impurity diffused simultaneously in interstitial and substitutional form, in another it diffused with the interstitial form being trapped at defects, and the other involved short-circuit paths. The data for the first and second mechanisms could be described by:

D (cm2/s) = 2.9 x 10-2 exp[-1.22(eV)/kT]

and

D (cm2/s) = 1.7 x 10-4 exp[-0.78(eV)/kT]

respectively.

P.Martin, A.Bontemps: Journal of the Physics  and Chemistry of Solids, 1980, 41[11], 1171-4