Encoding Morphology in Oxide Nanostructures during Their Growth

Programmable control over the overall structure of SnO(2) nanowires grown by vapor-solid synthesis is shown to be possible by pulse modulating the flow rate of the carrier gas in which oxygen (one of the reactants) is entrained. The control is shown to depend on the local oscillation of the supersaturation condition for the SnO vapor (another reactant) in the vicinity of the growing nanostructure. The latter triggers dramatic, reproducible oscillations in the lateral dimensions of the nanostructure and in the direction of its growth. The method provides a means for producing predictable morphological and compositional variations in 1D nanostructures, thereby potentially resulting in a high yield of custom-designed nanostructures.