Two fold coordinated silicon atom: a hole trap in SiO2

The capturing properties of a neutral diamagnetic two fold coordinated silicon atom with two paired electrons (silylene center =Si:) in SiO2 are studied with ab initio density functional method. We prove that this defect is a hole trap in SiO2. Hole capture results in creation of a paramagnetic two-fold coordinated silicon atom with unpaired electron =Si(+). According to this prediction silylene centers can be with silicon-silicon bonds responsible for the positive charge accumulation in MOS devices at ionising radiation.