Optical and structural analysis of ZnS core-shell type nanowires

ZnS core-shell type nanowires were grown by the hot filament chemical vapor deposition technique using ZnS powders as solid source and molecular hydrogen as reactant gas. The growth temperature was varied ranging from 200 to 400 °C. X-ray diffraction patterns and micro-Raman spectra show that the grown material is formed by hexagonal and cubic crystalline ZnS combined phases. Micrographs revealed the formation of nanostructures with a pyramidal morphology ending with long tips. The tip endings measurement gives 600 nm-length and 20 nm-diameter. High resolution images indicate the formation of the core-shell type nanostructures with metallic zinc core and polycrystalline ZnS shell. The photoluminescence spectra of the nanowires are caused by native defects, elemental sulfur species on the surface and structural defects in the nanostructures.