Studies on linear, nonlinear optical and excited state dynamics of silicon nanoparticles prepared by picosecond laser ablation

Abstract

We report results from our studies on the fabrication and characterization of silicon (Si) nanoparticles (NPs) and nanostructures (NSs) achieved through the ablation of Si target in four different liquids using ∼2 picosecond (ps) pulses. The consequence of using different liquid media on the ablation of Si target was investigated by studying the surface morphology along with material composition of Si based NPs. The recorded mean sizes of these NPs were ∼9.5 nm, ∼37 nm, ∼45 nm and ∼42 nm obtained in acetone, water, dichloromethane (DCM) and chloroform, respectively. The generated NPs were characterized by selected area electron diffraction (SAED), high resolution transmission microscopy (HRTEM), Raman spectroscopic techniques and Photoluminescence (PL) studies. SAED, HRTEM and Raman spectroscopy data confirmed that the material composition was Si NPs in acetone, Si/SiO2 NPs in water, Si-C NPs in DCM and Si-C NPs in chloroform and all of them were confirmed to be polycrystalline in nature. Surface morphological information of the fabricated Si substrates was obtained using the field emission scanning electron microscopic (FESEM) technique. FESEM data revealed the formation of laser induced periodic surface structures (LIPSS) for the case of ablation in acetone and water while random NSs were observed for the case of ablation in DCM and chloroform. Femtosecond (fs) nonlinear optical properties and excited state dynamics of these colloidal Si NPs were investigated using the Z-scan and pump-probe techniques with ∼150 fs (100 MHz) and ∼70 fs (1 kHz) laser pulses, respectively. The fs pump-probe data obtained at 600 nm consisted of single and double exponential decays which were tentatively assigned to electron-electron collisional relaxation (<1 ps) and non-radiative transitions (>1 ps). Large third order optical nonlinearities (∼10−14 e.s.u.) for these colloids have been estimated from Z-scan data at an excitation wavelength of 680 nm suggesting that the colloidal Si NPs find potential applications in photonic devices.

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

“…Contrary to the findings of previous studies, 27,45 our results show that the PL of Si NPs is not only different from that generated by laser interaction with the solvent, but, once separated, the emission from alkylcapped Si NPs, centred at 335 nm (3.64 eV), looks remarkably similar to the PL of chemically synthesized alkyl-capped Si NPs. Contrary to the findings of previous studies, 27,45 our results show that the PL of Si NPs is not only different from that generated by laser interaction with the solvent, but, once separated, the emission from alkylcapped Si NPs, centred at 335 nm (3.64 eV), looks remarkably similar to the PL of chemically synthesized alkyl-capped Si NPs.…”

“…4c), corresponding to the D and G bands of graphitic carbon, respectively, in addition Please do not adjust margins Please do not adjust margins to the Si phonon peak at ~500 cm -1 (Fig. 45 The UV Raman spectrum (325 nm) of the irradiated 1-octene control sample exhibits features corresponding to the D, G, and T bands, which are significantly broadened, and is typical of amorphous carbon products. 45 The UV Raman spectrum (325 nm) of the irradiated 1-octene control sample exhibits features corresponding to the D, G, and T bands, which are significantly broadened, and is typical of amorphous carbon products.…”

Review of ultrafast laser ablation for sensing and photonic applications

“…The magnitude of the χ (3) was estimated to be ∼1.93 × 10 −14 e.s.u. Semiconductor NPs were fabricated in different liquids by Hamad et al [158] by focusing ∼2 ps, 800 nm laser on silicon (Si) substrates. The average size distributions were found to be of gaussian nature around the diameter values of the synthesized NPs (in acetone, water, DCM, chloroform) being ∼9.5 nm, ∼37 nm, ∼45 nm and ∼42 nm respectively.…”

Study of Tunable Plasmonic, Photoluminscence, and Nonlinear Optical Behavior of Ag Nanoclusters Embedded in a Glass Matrix for Multifunctional Applications

“…Typically, the peak intensities used for the open and closed apertures were ≈0.1 GW cm −2 and ≈0.03 GW cm −2 , respectively. The complete details and schematic of the Z‐scan experiments have been explained in our previous works …”