Synthesis and optical properties of pencil-like and shuttle-like ZnO microrods

The pencil-like and shuttle-like ZnO microrods have been fabricated on Si (100) substrates by chemical vapor deposition. Structure characterization results show that the microrods are perfect single crystals with the wurtzite structure along the 0001] growth direction and have diameters ranging from 100 nm to 2 μm and lengths up to 10 μm. Room-temperature photoluminescence measurements of ZnO microstructures exhibit an intensive ultraviolet peak at 390 nm and a broad peak centered at about 526 nm, which can be attributed to the free exciton emission and the deep level emission, respectively. Cathodoluminescence measurements show the same ultraviolet and green emissions as seen in the photoluminescence results. A possible growth mechanism of ZnO microrods is finally proposed.