CATHODOLUMINESCENCE MICROCHARACTERIZATION OF THE DEFECT STRUCTURE OF IRRADIATED HYDRATED AND ANHYDROUS FUSED SILICON DIOXIDE

The irradiation-sensitive defect structure of pure anhydrous and hydra ted fused amorphous silicon dioxide (alpha-SiO2) has been investigated using cathodoluminescence (CL) microanalysis. Irradiation of SiO2 by a continuous stationary electron beam results in a subsurface, trapped -charge-induced electric field that causes the electromigration of mob ile charged defect species within the volume of irradiated specimen. C L emissions, observed between 300-900 nm at specimen temperatures betw een 5 and 295 K are identified with particular defect centers includin g the nonbridging oxygen-hole centers with strained bond and/or nonbri dging hydroxyl precursors (hydrated specimen only), the self-trapped e xciton, oxygen-deficient centers Such as the neutral oxygen vacancy an d/or the twofold coordinated silicon defect, and the charge-compensate d substitutional aluminum center.