From O out-diffusion profiles for Czochralski-type material at 500C, measured using secondary ion mass spectrometry, O diffusivities of between 2.5 x 10-14 and 4.0 x 10-14 cm2/s were deduced. These values were higher, by nearly four orders of magnitude, than the normal diffusivity. The diffusion of implanted 18O in float-zone material at 400 to 525C yielded secondary ion mass spectrometry profiles which consisted of an exponential decay of the O concentration. Exponential profiles of 18O above the background (1014/cm3), which were as deep as 0.004 to 0.016mm, also revealed direct evidence for enhanced long-range O diffusion. The enhanced diffusion was explained in terms of a fast-diffusing species which was in dynamic equilibrium with interstitial O.

S.T.Lee, P.Fellinger: Materials Science Forum, 1986, 10-12, 1021-6