Reactant-governing growth direction of indium nitride nanowires.

Hexagonal wurtzite InN nanowires are grown via a vapor-liquid-solid (VLS) mechanism with an Au catalyst. Microstructure characterizations of a large number of nanowires demonstrate that the growth direction of InN nanowires is governed by variable NH(3) flux. InN nanowires at a NH(3) flux of 10 standard cubic centimeters per minute (sccm) grow preferentially in a hexagonal close-packed (hcp) <1010> direction, while those at 100 sccm NH(3) flux favor the hcp <0001> direction. A free energy minimization model is proposed to interpret this phenomenon. The first-principles calculations reveal that the <1010> oriented nucleus has the lowest energy at the lower NH(3) flux. In contrast, when NH(3) flux is high, the <0001> oriented nucleus has the lowest energy.