Structural and electronic properties of peroxy linkage defect and its interconversion in fused silica

Defect interconversion occurs during the manufacturing or usage process in fused silica, which dramatically influences the performance of the devices. We report first-principle calculations of two similar defect structures, POL (Si-O-O-Si, peroxy linkage) and POR-E' pair center (Si-O-O ⋅ … ⋅ Si, peroxy radical with a three coordinated Si atom), in a 96-atom fused silica that unveils significantly more complex natures including predicted stable structure, electronic structure and optical properties. The preferable structures of POL and POR-E' pair are predicted to locate at 1.7 Å and 2.6 Å for the Si-O bond length, respectively. The quasi-particle G0W0 calculations are performed and an accurate bandgap is obtained to calculate the optical absorption properties. Our results not only give an insight into the structure interconversion of oxygen-excess intrinsic defects, but also explain why it is difficult to observe the absorption of the POL defect experimentally.