Dependence of photoluminescence peaks and ZnO nanowires diameter grown on silicon substrates at different temperatures and orientations

ZnO nanowires were grown on Si(1 0 0) and Si(1 1 1) substrates by a simple physical deposition method in a conventional tube furnace without the use of any catalyst. The substrates were placed at different temperature zones. ZnO nanowires with different diameters were obtained at different substrate temperatures. Photoluminescence (PL) spectroscopy has been employed to study the optical properties of ZnO nanowires with average diameters ranging from 29 to 75 nm. The shapes of the photoluminescence curves are dependent on the temperature and orientation of substrates. The ultraviolet photoluminescence peak exhibited a blue-shift in position with a decrease in the diameter of nanowires. Large diameter nanowires tend to have more intense UV emission.