Deterministic shape-selective synthesis of nanowires nanoribbons and nanosaws by steady-state vapour-transport

We demonstrate the deterministic shape-selective synthesis and growth of CdSe nanowires, nanosaws and nanoribbons by a simple vapour-transport process in a tube furnace. The key step, in order to achieve reproducible shape selectivity for a given set of deposition parameters, is to exclude any effects of the temperature ramping. We prove that an efficient precursor-flow shutter is achieved just by varying the total furnace pressure. We then present a shape-diagram linking the different nanocrystals morphologies to only two parameters: powder and substrate temperature. These are varied in the 550-700 degrees C and 400-600 degrees C range, respectively. A model explaining the shape control is discussed.