ARF-EXCIMER-LASER-INDUCED EMISSION AND ABSORPTION-BANDS IN FUSED-SILICA SYNTHESIZED IN REDUCING CONDITIONS

ArF-excimer-laser-induced luminescence and absorption bands in type-III fused silica synthesized in a reducing condition were investigated. The fused silica shows 4.4-eV emission and 5.8-eV absorption bands ascribed to be the E' center (= Si.). By annealing in various atmospheres, the creation of these bands is suppressed: The order of the suppression effect is as He approximately equals O2 > air > N2. The 5.8-eV band decays after cessation of the irradiation. To describe these phenomena we proposed a model that the precursor of these bands is the = Si-H H-O-Si = structure: By irradiating with an ArF-excimer-laser beam, the E' centers are created as = Si-H H-O-Si = --> = Si. H-O-Si = +H, and the E' center decays after cessation of the irradiation by recombining with the hydrogen. By annealing, the structures are changed by the reaction = Si-H H-O-Si = --> = S-O-Si = +H-2. This reaction is enhanced by removing the hydrogen molecules by annealing in helium and oxygen.