Structure and formation mechanism of blue-light-emitting centers in silicon and silica-based nanostructured materials

We propose a model of the blue-light-emitting center in silicon and silica-based materials on the basis of the density functional theory calculations. It has been shown that the dehydroxylation reaction involved in the annealing process of surface hydroxyl groups results in the formation of a defect pair consisting of a dioxasilirane, = Si(O-2), and a silylene, = Si:, center. The resulting defect pair has the allowed electronic transition energies of similar to 3.5 and similar to 5 eV, in agreement with the peak positions of the photoluminescence excitation spectra of the blue-light-emitting materials.