Formation mechanism of hydrogen-associated defect with an 11.9 mT doublet in electron spin resonance and red luminescence in 9SiO2:GeO2 fibers

Abstract

The nature and the origin of the 11.9 mT hyperfine doublets in electron spin resonance spectrum observed in 9SiO2:GeO2 fibers were examined. When fibers were heated in hydrogen atmosphere at 100 °C, the intensity of the doublet increased. When gamma-ray irradiated, the intensity drastically increased. The photoluminescence bands peaking at 1.91 eV (650 nm) and 1.83 eV (680 nm) excited with Ar ion laser operated at 488 nm were also observed in the treated fibers with the doublets. It should be noted that the relation between the photoluminescence and the doublets was found. The intensities of the photoluminescence peaking at 1.83 eV and the 11.9 mT ESR doublets have accumulation. The germyl radical was proposed as their structural model. The origin of the photoluminescence peaking at 1.91 eV was tentatively proposed as the small silicon particles with hydrogen impurities generated in the fibers.