Controlling the growth mechanism of ZnO nanowires by selecting catalysts.

The effect of catalysts on ZnO nanowire growth was investigated by comparing the performances of Au, Pt, and Ag nanoparticles. Additional control of growth was achieved by implementing a substrate temperature of either 800 degrees C with a ZnO/graphite powder source or 500 degrees C with a Zn powder source. At 800 degrees C, the vapor-liquid-solid mechanism plays a very important role when the Au and Pt nanoparticles are in the liquid phase. On the other hand, nanowires can also be grown on solid nanoparticles, that is, oxidized Ag at 800 degrees C and nanoscale cracks, that is, Pt at 500 degrees C, where, the vapor-solid is the only possible mechanism. At 500 degrees C, the vapor-liquid mechanism still dominates even though Au and Ag appear to be liquid, which is a result of high Zn vapor pressure.