Catalyst-Free Growth of Vertical Alignment ZnO Nanowire Arrays by a Two-Stage Process

Abstract

We successfully synthesized well aligned ZnO nanowire (ZnO NW) arrays on Si (100) and indium tin oxide (ITO) glass substrates at the low temperature of 500 °C by a two-stage growth process without metal catalyst. The synthesized ZnO NWs had diameters in the range of 50−100 nm and lengths in the range of 5−8 μm. X-ray diffraction showed that ZnO NW arrays had single-crystal wurtzite structures and grew along the c-axis. Photoluminescence spectra revealed that the ZnO NWs showed a strong UV band at 3.2 eV and a broad green band at 2.3 eV at room temperature. We also observed that the alignment situation and UV band emission of the ZnO NW arrays was enhanced with an increased O2 flow rate in the first stage. In addition, various O2 gas flow rates affected the morphologies of the ZnO nanomaterials. We present a detailed discussion regarding the growth behavior and mechanism of the ZnO NW arrays in this study.

Synthesis of vertically aligned ultra-long ZnO nanowires on heterogeneous substrates with catalyst at the root

“…As the basis for various applications, synthesis with control over size, orientation, and density is of great significance and very much desired. The main synthesis techniques include physical vapor deposition [1,5,24,25], chemical vapor deposition [26][27][28][29], pulsed layer deposition [30] and the wet chemical method [31][32][33]. For the widely employed vapor transport method, different growth mechanisms have been reported, including catalyst-assisted vapor-liquid-solid (VLS) growth and catalyst-free vapor-solid (VS) growth.…”

Effect of Ga-doping on the properties of ZnO nanowire

“…The synthesis of well-aligned ZnO nanowire arrays is highly important for the fabrication of optoelectronic devices. There are a number of reports of ZnO VLS nanowire growth [26][27][28][29][30][31][32][33]. However, the effect of growth conditions on the resulting ZnO nanowires and the growth mechanisms remain unclear.…”

The simple fabrication of nanorods mass production for the dye-sensitized solar cell

“…It can be classified into either physical or chemical methods [19,20] such as thermal hydrolysis [21], hydrothermal processing [22], sol-gel [23][24], vapor condensation [25], spray pyrolysis [26][27], pulse laser decomposition [28], laser ablation [29], thermal evaporation [30.31], pulse combustionspray pyrolysis [32], electro-mechanical [33], flame spray pyrolysis [34], direct precipitation [35] and thermal plasma [36,37,38]. More specific, the synthesis of ZnO nanorods has also been performed using various techniques such as hybrid wet chemical route [39], solution process at low temperature [40], physical evaporation [41][42][43], electrophoretic deposition [44], radio frequency (RF) magnetron sputtering [45], templating against anodic alumina membrane [46] and PTFE capillary tube reaction [47]. Nonetheless, it is important to note that the efficiency and size control still become major research problems in synthesizing ZnO nanoparticles [38].…”