Self-diffusion was measured at between 855 and 1388C in highly isotopically enriched 28Si layers. The profiles of 29Si and 30Si were determined by means of secondary-ion mass spectrometry. The temperature dependence of the self-diffusion coefficient could be accurately described, over 7 orders of magnitude (figure 16), by a unique diffusion enthalpy of 4.75eV. This single value indicated that self-interstitials dominated self-diffusion. The high accuracy of the data permitted the upper bound on the vacancy-assisted diffusion enthalpy to be estimated at 4.14eV; in agreement with theoretical calculations.

Silicon Self-Diffusion in Isotope Heterostructures H.Bracht, E.E.Haller, R.Clark-Phelps: Physical Review Letters, 1998, 81[2], 393-6