Catalyst-free metalorganic chemical-vapor deposition of ultrafine ZnO nanorods

We report on the catalyst-free growth and the photoluminescent (PL) properties of ultrafine ZnO nanorods. Employing metalorganic chemical-vapor deposition, we prepared ultrafine ZnO nanorods, with very thin, diameters below 10 nm, on Si substrates at growth temperatures of 800-1000°C without using any metal catalyst. Synchrotron radiation X-ray diffraction and transmission electron microscopy measurements revealed that those nanorods were single crystalline. Furthermore, from the PL spectra of the ultrafine ZnO nanorods, a systematic blue-shift in their PL peak position was observed with decreasing diameter, presumably due to the quantum-confinement effect along the radial direction in ZnO nanorods.