Well-aligned zinc oxide nanorods and nanowires prepared without catalyst

Without catalyst and at a low temperature (550 °C), well-aligned ZnO nanorods and nanowires were prepared on porous silicon substrates using a simple method. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results confirm that both the nanorods and the nanowires are perfect single crystals with the wurtzite structure. The diameters range from 40 to 100 nm. The growth directions are along the [0 0 0 1] axis. Photoluminescence (PL) spectra show that the UV emission shifts slightly to low frequency and the intensity of green emission decreases with the improvement of ZnO crystallization.