Photo-induced phenomena in sputtered GeO2 films

Macroscopic and microscopic changes in sputtered GeO₂ films induced by band-gap light from an ArF excimer laser have been studied. When irradiated at 1 atm, 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.