First principle study of neutral and charged self-defects in amorphous SiO2

We present a study of several neutral and charged self-defects in a model cell of amorphous silica. We performed ab initio calculations using plane waves pseudopotential method in the framework of density functional theory using the local density approximation. We show the structures and the corresponding formation energies for vacancies and interstitials in several charged states for every possible defect site in our amorphous supercell. The obtained results on amorphous silica are compared to previous ones on α-quartz. The oxygen interstitials are found to be the dominant defects. The variation of formation energies as a function of the Fermi level at 300 K are represented and analyzed.