Structure and optical properties of ZnS/SiO2 nanocables

The nanocables with a single crystal ZnS core and a thin amorphous SiO₂ shell were successfully synthesized by a simple thermal evaporation method with the mechanism of Vapor-Solid growth. Its morphology and microstructure were determined by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and photoluminescence spectroscopy (PL). The ZnS/SiO₂ nanocables have diameters in the range of 20 nm-250 nm, lengths of several tens of micrometers. The core of the nanocable has a cubic sphalerite structure with the coexistence of periodically alternating twins along the [111] growth direction and stacking fault. The nanocables show strong room-temperature photoluminescence with four emission bands centering at 548 nm, 614 nm, 649 nm and 670 nm that may originate to the impurity of ZnS, existence of Si and oxide-related defects.