Preparation and characterization of CdS/Si coaxial nanowires

CdS/Si coaxial nanowires were fabricated via a simple one-step thermal evaporation of US powder in mass scale. Their crystallinities, general morphologies and detailed microstructures were characterized by using X-ray diffraction, scanning electron microscope, transmission electron microscope and Raman spectra. The US core crystallizes in a hexagonal wurtzite structure with lattice constants of a = 0.4140 nm and c = 0.6719 nm, and the Si shell is amorphous. Five Raman peaks from the US core were observed. They are ILO at 305 cm(-1), 2LO at 601 cm(-1), A(1)-TO at 212 cm(-1), E-1-TO at 234 cm(-1), and E-2 at 252 cm(-1). Photoluminescence measurements show that the nanowires have two emission bands around 510 and 590nm, which originate from the intrinsic transitions of US cores and the amorphous Si shells, respectively. (c) 2006 Elsevier Ltd. All rights reserved.