Silica-coated ZnO nanowires

ZnO-core/SiO_x shell nanowires were successfully fabricated and their morphology, structure, Raman and photoluminescence properties were examined. Not only the sputter-coated product had an one-dimensional morphology, but the tubular structure of SiO_x shell was also continuous, smooth, and uniform, along the core nanowires. It was found that two fundamental modes (334, 437 cm⁻¹) and 2 s order modes (1106, 1156 cm⁻¹) of hexagonal ZnO appeared in the Raman spectrum of ZnO-core/SiO_x shell nanowires. The photoluminescence (PL) spectrum of the core-shell nanowires were deconvoluted into three Gassian functions, centered at 382, 500, and 758 nm, whether the subsequent thermal annealing was performed or not. The integrated intensities of UV (382 nm) and green (758 nm) emissions were changed by means of the shell-coating and thermal annealing. We have discussed the possible emission mechanisms.