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

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 high-performance and high-efficiency optoelectronic nanodevices for functional applications.