Crystal growth of ZnO micro and nanostructures by PVT on c-sapphire and amorphous quartz substrates

ZnO micro and nanostructures in the form of tripods, grains, arrows and wires have been grown at temperatures as low as 500–300 ∘C by a vapour transport method without catalysis and using a well selected value of the carrier gas flow. A transition state between grains and nanowires is reported being characterized by arrow-like structures which are constituted by a pyramidal head and a tail that is growing from the basal plane of the head. In order to understand the effect of growth conditions on the morphology of micro and nanostructures, an analysis of temperature and species concentration conditions has been carried out. In addition two different kinds of substrates have been used, namely quartz and c-sapphire.