Self-Nucleated Nonpolar GaN Nanowires with Strong and Enhanced UV Luminescence

Abstract

Compared with polar c-axis GaN, nonpolar GaN crystals with different orientations show distinct optical and electrical properties and thus some promising and functional applications can be expected. In this work, we report the self-assembled nucleation and synthesis of nonpolar GaN nanowires through a conventional chemical vapor deposition approach and systematic investigation of their microstructures and crystallography using a high-resolution transmission electron microscope. Comparative optical studies on polar and nonpolar GaN nanowires using monochromic and spatially resolved cathodoluminescence spectroscopy demonstrate that nonpolar GaN nanowires show strong UV luminescence, and an obvious blue shift of the peak wavelength along the nanowire from the bottom to the top is observed, while the yellow band emission observed in polar GaN nanowires is not detected. The feasible synthetic strategy and the peculiar luminescence property of nonpolar GaN nanowires will provide predominant advantages and sufficient space for the fabrication of highperformance and high-efficiency optoelectronic nanodevices for functional applications.

Highly Controllable Epitaxial Growth of High-Density Nonpolar GaN Nanorod Arrays

“…In recent studies, nonpolar GaN nanowires have shown unique optical and electrical properties. Liu and co-workers 8 synthesized nonpolar a-plane GaN nanowires through a conventional CVD process and found that nonpolar GaN nanowires have superior crystallinity and excellent luminescence property. Xiao et al 16 have identified the significance of the nonpolar GaN planes in promoting the PEC hydrogen evolution reaction through a combination of theoretical and experimental studies.…”

“…The difference in electronegativity leads to the formation of electric dipoles, which in turn results in spontaneous polarization. In order to avoid/overcome the polarization effect caused by the polar GaN, the research focusing on the growth of nonpolar GaN is gradually increasing, with one-dimensional nanomaterials being a significant component. − One-dimensional nanomaterials such as nanowires and nanorods are considered as promising candidates for next-generation high-performance devices because of their huge surface–volume ratio and highly regulable structure compared to bulk GaN crystal materials. , Various growth techniques have been applied to the growth of nonpolar GaN nanowires, including metal-catalyzed metal-organic chemical vapor deposition (MOCVD), direct nitridation/vapor transport, , and catalyst-free selective-area molecular beam epitaxy (SA-MBE) . And among the increasingly sophisticated preparation systems, the convenient chemical vapor deposition (CVD) method is one representative of the ways to prepare nanomaterials.…”

“…In recent studies, nonpolar GaN nanowires have shown unique optical and electrical properties. Liu and co-workers synthesized nonpolar a -plane GaN nanowires through a conventional CVD process and found that nonpolar GaN nanowires have superior crystallinity and excellent luminescence property. Xiao et al .…”