Data were obtained by using Fourier-transform infra-red spectroscopy. A model which assumed the sequential generation of thermal double-donors, and a fast-diffusing O dimer, was found to reproduce the experimental data. The diffusivity of the O dimer was estimated to be some 106 times that of interstitial O at 400C, and could be described by:

D (cm2/s) = 3 x 10-4 exp[-1.3(eV)/kT]

The value of the pre-exponential factor was very close to that for the jump frequency of interstitial O.

D.Aberg, B.G.Svensson, T.Hallberg, J.L.Lindström: Physical Review B, 1998, 58[19], 12944-51