Photoluminescence Properties of Silica Glass Doped with Germanium

SiO_2 glassy materials with Ge crystals embedded were formed by heating GeO_2/SiO_2 glass at 700 in the presence of hydrogen. GeO_2/SiO_2 glass was prepared with the sol-gel technique. The Ge/SiO_2 samples show a special photoluminescence property and exhibit strong luminescence at 392 nm(3.12 eV), secondary strong luminescence at 600 nm(2.05 eV) and weak luminescence at 770 nm(1.60 eV) when excited under 246 nm(5.01 eV) ultra-violet light at room temperature. The structure of this new luminescence material was studied with XRD, XPS, and TEM. The results show that the presence of nanometer sized(around 10 nm) Ge and GeO crystals in the SiO_2 may cause the three-band photoluminescence. The GeO_2/SiO_2 glass without going through the reducing process only has GeO_2 in the SiO_2 glass, and does not show the photo-(luminescence).