Isotopic exchange was used to measure the Si self-diffusivity in thermal silicon dioxide. The experiments, using an isotopically enriched 28Si oxide layer, were specially designed to obtain the actual equilibrium diffusivity in the oxide. A simple Arrhenius law, with an activation energy of 5.34eV, very closely described the measured diffusivities (figure 3) as a function of temperature.

Silicon Self-Diffusivity Measurement in Thermal SiO2 by 30Si/28Si Isotopic Exchange. D.Mathiot, J.P.Schunck, M.Perego, M.Fanciulli, P.Normand, C.Tsamis, D.Tsoukalas: Journal of Applied Physics, 2003, 94[3], 2136-8

Figure 3

Diffusivity of 30Si in SiO2