Luminescent silicon nanocrystals produced by near-infrared nanosecond pulsed laser ablation in water

Abstract

a b s t r a c tWe report the investigation of luminescent nanoparticles produced by ns pulsed Nd:YAG laser ablation of silicon in water. Combined characterization by AFM and IR techniques proves that these nanoparticles have a mean size of ∼3 nm and a core-shell structure consisting of a Si-nanocrystal surrounded by an oxide layer. Time resolved luminescence spectra evidence visible and UV emissions; a band around 1.9 eV originates from Si-nanocrystals, while two bands centered at 2.7 eV and 4.4 eV are associated with oxygen deficient centers in the SiO 2 shell.

Controlling luminescent silicon nanoparticle emission produced by nanosecond pulsed laser ablation: role of interface defect states and crystallinity phase

“…Considering the fact that HF removes the SiO x layer by chemical etching, the reduction in the rst peak (426 nm) can show us that this peak is mainly due to oxide related defects at Si/SiO x interface. This conclusion is in agreement with some of the previous studies where the blue emission is contributed to the defects at Si/SiO x interface 29,36 rather than direct recombination in ultra-small (<5 nm) Si nanocrystals (due to quantum connement). These studies show that the blue emission from Si nanocrystals is occurred at energy of 2.7 eV and this is mainly due to a forbidden triplet-tosinglet transition inside the SiO x shell layer.…”

Oxidation of silicon nanoparticles produced by nanosecond laser ablation in liquids

“…In agreement with previous experiments [8], the colloidal solution produced by LA consists of nanoparticles with an average diameter of a few nanometers and containing Si-nc as demonstrated by the characteristic Raman line at 518 cm −1 . We measured the mass of this product after drying the solution; it is ∼2.2 mg.…”

Photoluminescence analysis of colloidal silicon nanoparticles in ethanol produced by double-pulse ns laser ablation

“…Laser ablation of silicon in liquid media offers the possibility of production of well dispersed colloidal SiNPs with unique surface characteristics such as oxide, hydroxyl and alkyl surface passivations [6][7][8][9][10]. It was shown that the SiNP powders that prepared by PLA in liquids and drying the host liquid media mainly have the same surface characteristics as those of the colloidal samples [6,36,39]. Indeed, during the ablation process in liquids, a reaction between the solvent molecules with high temperature and pressure laser induced plasma can result in formation of stable surface products on the nanoparticles [55].…”

“…Especially, it was shown that PLA of silicon in different solvents can result in production of colloidal silicon nanoparticles (SiNPs) with remarkable optical properties which are applicable in optoelectronics and medicine [5][6][7][8][9][10][11][12][13][14][15]. In recent years, nanoscale structure of silicon with novel optical properties have received much attention due to the wide range of applications in light emitting diodes [16][17][18], lasers [19,20] and sensors [21].…”