Spontaneous Formation of AlInN Core--Shell Nanorod Arrays by Ultrahigh-Vacuum Magnetron Sputter Epitaxy

The spontaneous formation of AlInN core--shell nanorod arrays with variable In concentration has been realized by ultrahigh-vacuum magnetron sputter epitaxy with Ti 0.21 Zr 0.79 N or VN seed layer assistance. The nanorods exhibit hexagonal cross sections with preferential growth along the $c$-axis. A core--shell rod structure with a higher In concentration in the core was observed by (scanning) transmission electron microscopy in combination with low-loss electron energy loss spectroscopy and energy dispersive X-ray spectroscopy. 5 K cathodoluminescence spectroscopy of Al 0.86 In 0.14 N nanorods revealed band edge emission at ${\sim}5.46$ eV, which was accompanied by a strong defect-related emission at ${\sim}3.38$ eV.