Controlled modulation of diameter and composition along individual III-V nitride nanowires.

Semiconducting nanowires have unique properties that are distinct from their bulk counterparts, but realization of their full potential will be ultimately dictated by the ability to control nanowire structure, composition, and size with high accuracy. Here, we report a simple, yet versatile, approach to modulate in situ the diameter, length, and composition of individual segments within (In,Ga)N nanowires by tuning the seed particle supersaturation and size via the supply of III and V sources during the growth. By elucidating the underlying mechanisms controlling structural evolution, we demonstrate the synthesis of axial InN/InGaN nanowire heterojunctions in the nonpolar m-direction. Our approach can be applied to other materials systems and provides a foundation for future development of complex nanowire structures with enhanced functionality.