Silicon Nanocrystals Produced by Nanosecond Laser Ablation in an Organic Liquid

Abstract

Small (3-5 nm in diameter following HRTEM images) Si nanocrystals were produced in a two-stage process including (1) nanosecond laser ablation of a Si target in an organic liquid (chloroform) that results in formation of big composite polycrystalline particles (about 20-100 nm average diameter) and ( 2) ultrasonic post-treatment of Si nanoparticles in the presence of HF. The post-treatment is responsible for disintegration of the composite Si particles, release of small individual nanocrystals, and reduction of their size due to HF-induced etching of Si oxide. The downshift and broadening of the ∼520 cm -1 Raman phonon band of the small Si nanocrystals with respect to the bulk Si Raman band is consistent with the presence of ∼4.5 nm Si nanocrystals. The photoluminescence spectra (450-900 nm) and decay kinetics of small Si nanocrystals were detected, and the possible origin of the luminescence is discussed.

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

“…Numerous studies have been reported related to synthesis of silicon nanocrystals [7][8][9] by irradiating intense laser light onto these materials dispersed in solvents. It has been shown in various studies that changing the surrounding solvent can provide different effects on the SiNCs such as stability, absorption spectrum, size distribution and surface chemistry [8][9][10][11]. This synthetic flexibility of physical and chemical properties is one of the reasons why SiNCs colloids are good candidates for luminescent based devices.…”

Resolving the source of blue luminescence from alkyl-capped silicon nanoparticles synthesized by laser pulse ablation

“…For instance, ablation of a Si wafer in neat 1-octene results in blue luminescent Si NPs covered in a monolayer of n-alkyl chains as a result of the reaction between the Si surface radicals and the 1-octene. 5,17,22,23 Broad PL spectra in Si NP preparations have, in general, been attributed to a broad NP size distribution. 5,17,22,23 Broad PL spectra in Si NP preparations have, in general, been attributed to a broad NP size distribution.…”

Facile production of stable silicon nanoparticles: laser chemistry coupled to in situ stabilization via room temperature hydrosilylation

“…However, these methods generally face the major drawback of an intrinsically wide size distribution of the produced nanoparticles. 18 Furthermore, extended aging times, 17,19 or post-treatment with strong acids such as hydrofluoric acid (HF) to remove the amorphous and oxidized shell 20 are needed to obtain luminescent silicon nanocrystals. In contrast, bottom-up approaches may be preferred given the higher control of size and shape distributions.…”