Ultra-fine beta-SiC quantum dots fabricated by laser ablation in reactive liquid at room temperature and their violet emission

A simple and flexible route is presented for the fabrication of ultrafine beta-SiC quantum dots (QDs) based on laser ablation of silicon wafers immersed in ethanol and subsequent etching. The obtained beta-SiC QDs are nearly monodispersed and about 3.5 nm in size. The relative content of beta-SiC after laser ablation depends on the liquid phase's ability to supply carbon atoms at a certain laser fluence. Proper liquid media with appropriate carbon atoms supply capacity can lead to nearly pure beta-SiC in the as-prepared sample. The obtained beta-SiC QDs exhibit strong and stable emission in the violet region, significantly blue-shifting relative to that of bulk SiC. This big blue shift of emission is attributed to the significant quantum confinement effect induced by their ultrafine size. This method can be extended to produce some other ultrafine Si compounds which are usually formed at high temperature and/or high pressure. This study could present the building blocks of nanostructured devices as violet light sources and new materials in biological molecular labels.