Abstract
Silicon nanoparticles (Si-NPs) were prepared by solution-based chemical etching method. Optical characteristics of the as-prepared Si-NPs were investigated in different polar and nonpolar organic solvents. The emission and absorption properties of Si-NPs were tuned by altering the environment (solvents). The variation in absorption coefficient was observed because of the solvent interaction nature of Si-NPs. Si-NPs in polar aprotic and nonpolar solvents manifested good luminescence under UV excitation. PL intensities were observed to be depending on etched cross-section area on wafer surface. The results show a linear dependence of the refractive index (n) on wavelength (λ). The nature of solvents altered the luminescence efficiency of Si-NPs when examining under UV lamp. The emission and absorption properties of Si-NPs were tuned by altering the environment (solvents) through electrostatic interaction of various organic solvents with the Si-NPs. The band shapes of the Si-NPs show remarkable changes in passing from noncoordinating solvent (chloroform) to various coordinating solvents, which was the result of change in the environment around Si-NPs in various solutions.
Highlights
Silicon nanoparticles (Si-NPs) can be classified into a family of discrete sizes that includes 1.0, 1.67, 2.15, 2.9, and 3.7 nm diameters [1]
The band shapes of the Si-NPs show remarkable changes in passing from noncoordinating solvent to various coordinating solvents, which is the result of change in the environment around Si-NPs in various solutions and suggests coordination of solvent molecule(s), in some cases
Optical absorption spectroscopy was employed to investigate the optical properties of synthesized Si-NPs in the UV-Vis (200–600 nm) region in different solvents after four rounds of wafer etching at room temperature
Summary
Silicon nanoparticles (Si-NPs) can be classified into a family of discrete sizes that includes 1.0, 1.67, 2.15, 2.9, and 3.7 nm diameters [1]. Silicon has been considered as unsuitable for optoelectronic applications because bulk silicon emits hardly any useful light due to its indirect band gap nature This opinion was deeply changed after the discovery of bright emission from porous silicon and NPs. The possibility of constructing optoelectronic devices, Si-based integrated circuits, and sensors based on silicon has generated tremendous interest in the preparation and characterization of light-emitting Si-NPs. the first porous silicon layer was observed by Uhlir in 1956 [4] and later by Turner [5], it was only during Canham in 1990 after reporting about room temperature luminescence that there began significant interest in this material [6]. We employed various polar and nonpolar organic solvents such as ethanol, DMSO, DMF, dioxane, acetonitrile, chloroform, carbon tetrachloride, benzene, and hexane Because of their different surface functional groups, they make hydrogen bond with Si-NPs and altered the luminescence efficiency of the nanomaterials. Different parameters including absorption coefficient, reflectance, reflective index, dielectric constant, optical conductivity, and energy band gap were applied to investigate the optical behavior of Si- NPs in various solvents
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