Synthesis of si nanoparticles from freestanding porous silicon (ps) film using ultrasonication

Porous Silicon (PS) is one of the established materials and can be used in variety of applications in its different forms. Use of monolayer PS film for synthesis of Si QDs is reported here. Nanometer-sized silicon particles are produced by ultrasonic dispersion of thin films in DI water. PS films are characterized using cross sectional scanning electron microscopy and gravimetric analysis while the Si nanopowder is characterized by Raman spectroscopy, Photoluminescence (PL), UV-visible spectroscopy (UV-vis) and FTIR spectroscopy. Sonication for hours causes breaking and oxidation in the film. This reflects as frequency downshift in Raman spectroscopy. Raman peak are resolved into two peaks to study shell type structure of Si nanopowder synthesized. PL exhibits overall red peak shift. Decreasing Tauc bandgap and sharp absorption edge in UV-vis spectra confirms the presence of oxygenated Si nanoparticles in the material tested, confirmed by FTIR. Analysis of all spectra is explained in terms of shell structured Si nanoparticles with Quantum Confinement Luminescent Centre (QCLC) model.