Low-Temperature Selective Area Epitaxy of GaN Nanowires: Toward a Top-Surface Morphology Controllable, Fully Epitaxial Nanophotonic Platform
Mohammad Fazel Vafadar, Songrui Zhao
Abstract
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.