Growth mechanism and photoluminescence of the SnO2 nanotwists on thin film and the SnO2 short nanowires on nanorods

SnO₂ nanotwists on thin film and SnO₂ short nanowires on nanorods have been grown on single silicon substrates by using Au--Ag alloying catalyst assisted carbothermal evaporation of SnO₂ and active carbon powders. The morphology and the structure of the prepared nanostructures are determined on the basis of field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), selected area electronic diffraction (SAED), high-resolution transmission electron microscopy (HRTEM), x-ray diffraction (XRD), Raman and photoluminescence (PL) spectra analysis. The new peaks at 356, 450, and 489 nm in the measured PL spectra of two kinds of SnO₂ nanostructures are observed, implying that more luminescence centres exist in these SnO₂ nanostructures due to nanocrystals and defects. The growth mechanism of these nanostructures belongs to the vapour--liquid--solid (VLS) mechanism.