Search

Abstract: Oxy-chalcogenide glasses with compositions of xGeO2–(100− x)GeS2, where 0⩽ x ⩽100mol%, have been prepared and studied in terms of their structures and optical properties. X-ray fluorescence spectroscopy shows that Ge:S ratio can deviate from GeS2 by ∼10at.%, depending critically upon the preparation conditions. Raman scattering spectroscopy suggests that stoichiometric GeO2–GeS2 glasses have a heterogeneous structure in the scale of 1–100nm. The optical gaps are nearly constant at 3.0–3.5eV for glasses with 0⩽ x ⩽80mol% and abruptly increase to ∼6eV in GeO2. This dependence suggests that the optical gap is governed by GeS2 clusters, which are isolated and/or percolated. Composition-deviated glasses appear as orange and brown, and these glasses seem to have more inhomogeneous structures. [Copyright &y& Elsevier]

Abstract: Photo-induced changes in GeO2 glass have been studied in terms of its optical and structural properties. Band-gap excitation gives rise to modifications in mid-gap optical absorption and photo-luminescence spectra. It also produces electron-spin signals at g ≃1.995 and 2.008. Raman-scattering spectrum becomes sharper, X-ray diffraction patterns show a disappearance of a crystalline peak, and the illuminated surfaces expand. These observations can be accounted for by assuming bond transformations from rutile-like to defective quartz-like structures and/or from small to large rings. These photo-induced changes in GeO2 are discussed in comparison with those in SiO2 and GeS2. [Copyright &y& Elsevier]

Abstract: Macroscopic and microscopic changes in sputtered GeO2 films induced by band-gap light from an ArF excimer laser have been studied. When irradiated at 1atm, the film thickness increases, surface-roughness increases, refractive-index decreases, hygroscopic enhancements, and Ge–O–Ge distance increases. Irradiations in vacuum make these changes smaller or undetectable. These photo-induced changes are discussed from phenomenological and structural viewpoints, and compared with characteristics in GeO2–SiO2 and GeS2 films. [Copyright &y& Elsevier]