Light-emitting properties of Si-ion-irradiated SiO₂/Si/SiO₂ layers

Photoluminescence (PL) from a Si-ion-irradiated SiO₂/Si/SiO₂ layer on a Si substrate at room temperature has been studied to elucidate the luminescence behavior under various post-annealing treatments. A luminescence band around 450 nm is observed from the as-irradiated sample. This luminescence band is found to originate from the diamagnetic defect, known as the B₂ band, generated by Si ion irradiation. The intensity of this band increases with the increasing annealing temperature up to a critical temperature after Si irradiation. The B₂ band activates at a lower temperature than the radiative defect related to the PL peak around 600 nm. After the ion-irradiated samples are annealed at 1100 °C, the PL peaks around 450 nm and 600 nm originating from radiative defects disappear, and a new PL peak appears around 720 nm. This luminescence band is associated with the ∼5-nm-sized Si nanocrystals produced along the Si layer between SiO₂ layers, as determined by high resolution transmission electron microscopy. The intensity of the PL peak from the ion-irradiated SiO₂/Si/SiO₂ layer is stronger than that from the Si-implanted SiO₂ film and that from the SiO₂/Si/SiO₂ layer annealed without Si irradiation.