Post-Treatment od Silicon Nanocrystals Produced by Ultra-Short Pulsed Laser Ablation in Liquid: Toward Blue Luminescent Nanocrystal Generation

Date
2012-01-11
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Source Title
Journal of Physical Chemistry C
Print ISSN
1932-7447
Electronic ISSN
Publisher
American Chemical Society
Volume
116
Issue
5
Pages
3432 - 3436
Language
English
Type
Article
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Abstract

Blue luminescent colloidal silicon nanocrystals (Si-NCs) were produced in a two-stage process. In the first step, synthesis of Si-NCs was achieved by femtosecond pulsed laser ablation of a silicon wafer, which was immersed in deionized water. The size and the structural and the chemical characteristics of colloidal Si-NCs were investigated by TEM and EDAX analyses, and it is found out that the Si-NCs are in spherical shape and the particle diameters are in the range of 5-100 nm. In the second step, ultrasonic waves and filtering chemical-free post-treatment of colloidal Si-NCs solution was performed to reduce the particle size. High-resolution TEM (HRTEM) studies on post-treated colloidal solution clearly show that small (1-5.5 nm in diameter) Si-NCs were successfully produced. Raman spectroscopy results clearly confirms the generation of Si nanoparticles in the crystalline nature, and the Raman scattering study of post-treated Si-NCs confirms the reduction of the particle size. The UV-vis absorption and photoluminescence (PL) spectroscopy studies elucidate the quantum confinement effect of Si-NCs on the optical properties. The colloidal Si-NCs and post-treated Si-NCs solutions present strong absorption edge shifts toward UV region. Broadband PL emission behavior is observed for the initial colloidal Si-NCs, and the PL spectrum of post-treated Si-NCs presents a blue-shifted broadband PL emission behavior due to the particle size reduction effect.

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Keywords
Absorption edges, Blue-shifted, Chemical characteristic, Colloidal solutions, Crystalline nature, Femtosecond pulsed laser ablation, High-resolution tem, Luminescent nanocrystals, Particle diameters, Particle size reduction, Pl emission, Pl spectra, Post treatment, Quantum confinement effects, Si nanoparticles, Silicon nanocrystals, Spherical shape, Two-stage process, Uv region, Uv-vis absorptions
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Published Version (Please cite this version)