Oxygen role on the structural and optoelectronic properties of silicon nanodots

The aim of this work is to elucidate, through density functional calculations, the role of the Si–O interface bonds on the structural, electronic and optical properties of Si nanodots in order to explain the peculiar properties of aged porous Si samples and heavily oxidized Si nanoparticles. For isolated dots we show that the presence of Si=O bond results in a strong reduction of the energy gap. For Si nanodots embedded in SiO₂ we show that both the Si–O bonding and the deformation of the cage play an important role.