Modulation of the photoluminescence of Si quantum dots by means of CO2 laser pre-annealing

Si quantum dots (QDs) embedded in SiO2 can be normally prepared by thermal annealing of SiOx (x<2) thin film at 1100°C in an inert gas atmosphere. In this work, the SiOx thin film was firstly subjected to a rapid irradiation of CO2 laser in a dot by dot scanning mode, a process termed as pre-annealing, and then thermally annealed at 1100°C for 1h as usual. The photoluminescence (PL) intensity of Si QD was found to be enhanced after such pre-annealing treatment. This PL enhancement is not due to the additional thermal budget offered by laser for phase separation, but attributed to the production of extra nucleation sites for Si dots within SiOx by laser irradiation, which facilitates the formation of extra Si QDs during the subsequent thermal annealing.