ZnO nanowire growth: A deeper understanding based on simulations and controlled oxygen experiments

A binary flow of a Ar/Zn mixture has been used in simulations as well as in physical growth experiments for ZnO nanowire growth by vapor phase deposition. Systematic investigations of the gas transport and the chemical behavior under controlled vacuum and flow conditions revealed that the gases emerging from carbothermal reduction, namely, CO(g) and CO2(g), are not enough to stimulate a controlled ZnO nanowire growth. An optimum O-2 concentration is crucial to promote nanowire growth, while CO(g) and CO2(g) enhance the tendency to grow a film. importantly, the here presented simulations can be used to predict and tailor the region of nanowire growth under appropriate assumptions for any tube furnace.