Blue-green luminescent silicon nanocrystals fabricated by nanosecond pulsed laser ablation in dimethyl sulfoxide

Abstract

In this work, stable blue-green luminescent colloidal silicon nanocrystals (SiNCs) are fabricated by nanosecond pulsed laser ablation of a silicon target in dimethyl sulfoxide (DMSO). Transmission electron microscopy and X-ray diffraction analysis have shown the formation of spherical silicon nanocrystals in the colloid with size range of 2-5 nm. Our results show that the DMSO stabilizes the silicon nanocrystals via oxide formations on the nanocrytals surfaces by a simple route of laser ablation and a schematic representation of the process is suggested. The colloid exhibits strong blue luminescent emissions in the spectral range of 455-465 nm when excited at wavelengths near the direct band gap of the silicon nanocrystal. The luminescent emission band shifts to longer wavelengths (green light) if the excitation wavelength increases toward the indirect band gap of the SiNCs. The oxidized SiNCs with quantum confinement effects are shown to be responsible for visible photoluminescence of the colloid. The observed blue-green emission of the colloid makes it a good candidate for display, solid-state lighting and biological luminescent based devices.