Optical properties of silicon nanocrystallites prepared by pulsed laser ablation in inert gas ambient

We report nanometer-sized silicon (Si) crystallites prepared by pulsed laser ablation in constant pressure inert gas ambient. Size distribution of the Si ultrafine particles depends on the pressure of inert gas ambient. It is verified that the size of the Si ultrafine particles is approximately 3 nm and greater in diameter. The nanoscaled ultrafine particles has a crystallinity similar to that of bulk Si. Furthermore, optical properties of the Si nanocrystallites have been studied in terms of the particle size. Visible photoluminescence (PL) bands in the red and green spectral regions appear at room temperature after an oxidation process. The red PL band is independent of the particle size and is stable without degradation by the irradiation of excitation light. In contrast, the green PL band depends on the particle size. The green PL intensity decreases during the irradiation of excitation light in air, and then recovers in the subsequent vacuum evacuation.