Growth and optical properties of single-crystal tubular ZnO whiskers

The growth of single-crystal tubular ZnO whiskers was achieved via a process of first reduction and following oxidation of ZnS powders. The products were characterized using x-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, and photoluminescence spectroscopy. The whiskers are tubular single crystals with the [001] growth crystallographic direction, and most have outer diameters of $\text{∼400\hspace{0.17em}}\mathrm{nm},$ lengths of up to 15 μm, and wall thickness range of 100–150 nm. Room-temperature photoluminescence spectrum of the whiskers reveals a strong and sharp UV emission band at 381 nm and a weak and broad green emission band at 583 nm. Possible growth mechanism of the ZnO whiskers was briefly discussed.