The migration of F in vapor-deposited silica layers was studied at temperatures of between 1600 and 2000C. By combining the present results with the data of other workers, it was found that the diffusivity of F could be described by a concentration-independent coefficient of the form:

D(cm2/s) = 1.74 exp[-383(kJ/mol)/RT]

at temperatures of between 1000 and 2000C. The value of the coefficient was not affected by the presence of Cl, but was affected by hydroxyl contents of more than 0.05mol%. Also, co-dopants such as P had a marked effect upon F diffusion. The diffusivity of Cl within the same temperature range was described by:

D(cm2/s) = 0.000281 exp[-211(kJ/mol)/RT]

These values were not affected by normal F or hydroxyl contents.

J.Kirchhof, S.Unger, K.F.Klein, B.Knappe: Journal of Non-Crystalline Solids, 1995, 181[3], 266-73