International audienceThis article compares the forms and properties of ZnO nanostructures grown on Si(111) and c-plane sapphire (c-Al(2)O(3)) substrates using three different growth processes: metal organic chemical vapor deposition (MOCVD), pulsed laser deposition (PLD), and physical vapor transport (PVT). A very wide range of ZnO nanostructures was observed, including nanorods, nanoneedles, nanocombs, and some novel structures resembelling "bevelled" nanowires. PVT gave the widest family of nanostructures. PLD gave dense regular arrays of nanorods with a preferred orientation perpendicular to the substrate plane on both Si and c-Al(2)O(3) substrates, without the use of a catalyst. X-ray diffraction (XRD) studies confirmed that nanostructures grown by PLD were better crystallized and more highly oriented than those grown by PVT and MOCVD. Samples grown on Si showed relatively poor XRD response but lower wavelength emission and narrower linewidths in PL studies

One dimensional (1D) ZnO heterostructures were deposited on C-plane sapphire using metal organic chemical vapor deposition at atmospheric pressure. Both catalyst-assisted and catalyst-free processes were investigated. In this latter case, growth parameters such as the substrate temperature, the oxygen/zinc ratio, or the carrier gas nature were varied in order to observe the modification of the film morphology. Different 1D shapes were produced, including rods, tubes, and needles, and were observed by scanning electron microscopy. Photoluminescence spectra reveal sharp excitonic transitions, and cathodoluminescence signals recorded along a ZnO conical needle exhibit a blueshift from the base to the top. The vapor-liquid-solid growth of ZnO nanowires using gold droplets was also successful.

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