A computational study of Si-H bonds as precursors for neutral E ′ centres in amorphous silica and at the Si/SiO2 interface

Using computational modelling we investigate whether Si-H Bonds can serve as precursors for neutral E ′ centre formation in amorphous silica and at the Si/SiO2 interface. Classical inter-atomic potentials are used to construct models of a-SiO2 containing Si-H bonds. We then investigate the mechanism of dissociation of a Si-H bond to create a neutral E ′ defect, that is a 3-coordinated silicon with an unpaired electron localised on it. We show that the Si-H bond is extremely stable, but as a result of hole injection it is significantly weakened and may dissociate, creating a neutral E ′ centre and a proton attached to one of the nearby oxygen atoms. The proton can diffuse around the E ′ centre and has a profound effect on the defect levels. We show that at a Si/SiO2 interface, the position of the proton can facilitate electron transfer from the Si substrate onto the defect, making it negatively charged. © 2013 Elsevier B.V. All rights reserved