Figure 7 SEM images of NW-NWL hybrid, ZnO NWL, and nanofin-NW hybrid. (a) Low magnification 52° side-view SEM image of the NW-NWL hybrid. Inset, higher magnification 52° SEM image shows the formation of NWL. Scale bar is 500 nm. (b) Top-view SEM image of ZnO NWL. Inset, higher magnification

52° side-view SEM image of the sample. Scale bar is 1 μm. (c) Top-view SEM image shows the presence of Au catalyst at the root and Zn cluster drift in random directions terminated with growth of NW. Inset shows higher magnification 52° side-view SEM image of the sample. Scale bar is 200 nm. www.selleckchem.com/products/ABT-263.html (d) Low magnification 52° side-view SEM image of the nanofin-NW hybrid. Inset shows higher magnification 52° side-view SEM image of the sample. Scale bar is 500 nm. To follow the morphological evolution of the ZnO nanostructures, time-dependent growths were also carried out on the SiC substrates using the different Au nanoparticle densities. For this present investigation, the growth temperature was fixed at 900°C, while the growth times were either 90 or 180 min. Figure 7 presents the experimental results obtained for ZnO nanomaterial synthesis as a function of time. In Figure 7a, b, the growth of the ZnO NW-NWL hybrids and NWLs is obtained by varying time between

90 and 180 min, respectively, Selleckchem CHIR 99021 for the high-density Au nanoparticle case. Once again, the drifting was effectively halted by Zn clusters merging with other clusters and/or Au seed nanoparticles resulting in the formation of complete ZnO networks over large areas of the SiC substrates, as already shown in Figure 6b. When growing with low-density Au nanoparticles, the following Idoxuridine observations can be made: (i) the drift of the Zn cluster results in the formation of vertically oriented ZnO NWs at the Zn cluster drift sites and not at the seed particle site as shown in Figure 7c, and (ii) with increasing growth time (Figure 7d), a new form of nanostructure can be observed, in which NWLs are effectively terminated by NWs at one end. These observations were found to be consistent with the

so-called nanofins, reported in [19]. With longer synthesis time (180 min), we observed that the boundaries between ZnO NWs and horizontal trace of the Zn cluster were more favorable nucleation sites, forcing the growth of the observed ZnO nanofin-NW structures. Based on the experimental observations, the growth mechanisms for ZnO nanoarchitectures at 900°C are schematically illustrated in Figure 8. The first step of the process is the conversion of the Au thin film into spherical- and/or hexagonal-shaped nanoparticles, described by the ripening process [28]. The density of the Au nanoparticles, which can be controlled by the thickness of the sputtered Au layer, plays a key role in determining the final morphology of ZnO nanostructure.