Quantum-confined and tunable optical emission from sub-10-nm silicon oxide nanowires in aqueous suspension

Silicon oxide nanowires (SiONWs) smaller than 10nm were synthesized by vaporization of SiO2 powders without catalytic assistance. The SiONWs resemble bamboos and the knots comprise Si nanocrystals of different orientations. A SiONW water suspension prepared ultrasonically was subjected to photoluminescence and photoluminescence excitation spectral examinations. Strong blue emission which arises from band-to-band recombination in the quantum confined Si nanocrystals in the knots is observed. Our results show that the emission characteristics can be tuned by adjusting the size of the knots.