Oxygen-deficient centres in silica glasses synthesised by a laser distillation method

Laser distillation was used to synthesise silica glasses containing oxygen-deficient centres (ODCs). The dependences of the ODC concentration on the compositions of the starting materials and of the atmosphere were studied. Synthesis under neutral and reducing conditions generated silicon ODCs in a concentration of ~10¹⁶ cm^-3. Similar silicon ODC concentrations were attainable by quenching from above 1300 K. Distillation purification intended to remove the Ge impurity reduced concentration of germanium ODCs by a factor of ~100. The dependences of the absorption and luminescence spectra of the synthesised glasses on the Ge concentration confirmed that the 5.04 eV absorption band was typical of the silicon ODCs and the 5.16 eV band was typical of the germanium centres.