The diffusion of Sb in thin films which had been grown by means of low-temperature molecular beam epitaxy was investigated at temperatures ranging from 750 to 900C, and times of between 0.25 and 60h. The small spatial extent of the initial -function-like dopant profiles permitted the detection of very small diffusional displacements. The dopant atoms were used as tracers of Si point defects (vacancies and self-interstitials). The diffusion of Sb was found to be enhanced relative to the equilibrium values. A model was proposed which was based upon an initial supersaturation of vacancies. The matching of this model to experimental data permitted the extraction of the vacancy diffusivity, the activation energy for vacancy formation, and the recombination lifetime of interstitials. The results showed that the interstitial and vacancy populations could not be considered to be independent at low temperatures, as had previously been suggested.

H.J.Gossmann, C.S.Rafferty, A.M.Vredenberg, H.S.Luftman, F.C.Unterwald, D.J.Eaglesham, D.C.Jacobson, T.Boone, J.M.Poate: Applied Physics Letters, 1994, 64[3], 312-4