The study of oxygen-deficient centers in Al-doped amorphous germanium oxides

Abstract Electronic and optical properties of Germanium oxygen-deficient center (GeODC) defect and Al-doped GeODC defect in 96 atoms amorphous GeO2 (a-GeO2) supercells have been investigated. All the 64 oxygen sites in the a-GeO2 configuration have been orchestrated as possible candidates for the construction of 64 different GeODCs. A Ge atom has been substituted by an Al atom in GeODCs to form the Al-GeODCs. It is discovered that the refractive index of a-GeO2 is reduced by GeODC defect, contrary to the situation when Al is doped in GeODC defect. The absorption peak at 5.15 eV is related to GeODC defect. After Al-doping, a new defect state is generated near the top of valence band (TVB), resulting in an absorption peak at 4 eV. The variations of refractive index and optical properties exhibited offer a significant and profound guidance of Al and Ge co-doping in silica optical fiber.