Gallium nitride (GaN)/alumina (Al2O3) core-shell structures were successfully synthesized by a simple and one-step thermal evaporation method. We characterized their morphology, microstructures, and optical properties by SEM, TEM, EDX, and photoluminescence (PL). The core-shell structures were comprised of a core of single crystalline, GaN nanowires surrounded by a shell of Al2O3 tubular structures. We proposed a base-growth process as the dominant mechanism for the growth of the core/shell nanowires. We have discussed the possible reason for the preferential formation of the Al2O3 shells on the outside of the core-shell structures. In regard to the core/shell structures, an emission peak of 3.3 eV was observed in the roomtemperature PL measurements in addition to the GaN-associated peaks, and was attributed to the Al2O3 shell.

Keywords: GaN, Nanowires, Alumina, Photoluminescence, Growth mechanism.