DIFFUSION BEHAVIOR OF FLUORINE IN SILICA GLASS

Fluorine diffusion has been studied between 1600 and 2000 degrees C in vapour-deposited silica layers. In particular, the influence of the c ommon impurities hydroxyl and chlorine and the codopant phosphorous ox ide was investigated. Hydroxyl and especially phosphorous enhance the fluorine diffusion rate whereas chlorine shows no detectable effect. T he determined Arrhenius dependence of the diffusion coefficient agrees well with previous investigations made at lower temperatures. Additio nally, diffusion coefficients for chlorine were derived.