The role of activation energy distributions in diffusion related annealing in SiO2

Models for annealing processes in damaged, amorphous SiO2 are discussed. Using a series expansion approach, theories developed for diffusion-limited recombination are adapted to allow for a Gaussian distribution of activation energies. It is found that the effect of a distribution having deviation ΔE, and center EA can be accounted for by using an effective diffusion coefficient, D̃, such that in the series expansion any power (n) is defined by (D̃)n=Dn0 exp 1/2 (nΔE/kT)2 exp(−nEA/kT). This form is more complicated than that found previously for ‘‘pure’’ diffusion studies. The importance of the form of the distribution function for the activation energies is discussed in the context of the full diffusion-limited theory for annealing. It is argued that processes occurring at temperatures in excess of 500 °C are not due to diffusional recombination.