Special film structures were grown, by means of low-temperature molecular beam epitaxy. It consisted of a superlattice which was made up of B spikes which were separated from each other by 100nm of Si. After dry oxidation, the width of each spike was directly proportional to the interstitial concentration at that depth. The superlattice as a whole thus furnished a depth profile of the time-averaged interstitial concentration. The abrupt dopant concentration transitions which were achievable in low-temperature molecular beam epitaxial films permitted this type of investigation to be carried out at  between 750 and 900C. A value of 1.4 x 10-13cm2/s was found at 800C. Overall, the results could be described by:

D(cm2/s) = 100 exp[-3.1(eV)/kT]

H.J.Gossmann, C.S.Rafferty, H.S.Luftman, F.C.Unterwald, T.Boone, J.M.Poate: Applied Physics Letters, 1993, 63[5], 639-41