Nanocrystalline silicon and carbon nanotube nanocomposites prepared by pulsed laser fragmentation

This paper outlines the synthesis of nanocrystalline silicon (nc-Si) by nanosecond pulsed laser fragmentation of Si micrograins in liquid solutions, and characterization of the products. We compare micrograin fragmentations in deionized water, and in undoped and phosphorus-doped ethylpolysilicate (C(2)H(5)O[SiO(C(2)H(5)O)(2)](n) C(2)H(5)) based polymers. We show that dissolution and subsequent laser fragmentation of micrograins is more efficient in both polymeric media than in water. In the case of water, microgram surface wetting by ethanol prior to introduction into water is essential to achieve fragmentation. Prepared nc-Si/polymer nanocomposites display visible photoluminescence (PL) (similar to 430 nm) at room temperature. The phosphorus polymer induces a blue shift of the PL peak. In addition, induced shock waves generated at sufficiently high laser irradiation intensities (>4.3 mJ/pulse) cause carbon nanotube (CNT) cavities to be filled by freshly prepared luminescent nc-Si/polymer nanocomposite.