Low-Temperature Selective Area Epitaxy of GaN Nanowires: Toward a Top-Surface Morphology Controllable, Fully Epitaxial Nanophotonic Platform

Gallium nitride (GaN) nanowires by selective area epitaxy (SAE) are an emerging platform for nanophotonic devices. Nonetheless, the use of a high substrate temperature in SAE limits the development of this technology. In this work, we report the SAE of GaN nanowires at low substrate temperatures by radio frequency plasma-assisted molecular beam epitaxy. Excellent selectivity is obtained at low substrate temperatures; the area without patterning is nearly free of any growth. Furthermore, a delicate control on the nanowire top-surface morphology is enabled by the low temperature epitaxy from an irregular shape to a hexagonal shape with semipolar top planes to a hexagonal shape with polar c-planes on top with controlled polar c-plane size. Such a low temperature SAE of GaN nanowires, together with the elegant control of the nanowire top-surface morphology, will enable a fully controllable, epitaxial nanophotonic platform, benefiting the development of a wide range of photonic devices such as light-emitting diodes, lasers, single photon sources, and multifunctional photonic devices.