Selective Growth of Straight and Zigzagged Ga₁₋xMnxN (0 ≤ x ≤ 0.05) Nanowires and Dependence of Their Electronic Structure and Magnetization on the Mn Content

Straight and zigzagged Ga 1- x Mn x N (0 ≤ x ≤ 0.05) nanowires were selectively synthesized by the vapor transport method, using different growth temperature. They consisted of single-crystalline wurtzite GaN nanocrystals grown along the [101̄0] and [0001] directions for the straight and zigzagged morphologies, respectively. The lattice constant, c, decreases initially with increasing amount of Mn doping ( x ), and then increases as x increases above 0.03. X-ray photoelectron spectroscopy revealed that as the Mn content increases to x = 0.02, the binding energy of Ga 2p shifts to a higher energy, suggesting the possibility of hybridization between the Mn 2+ ions and host defects. X-ray absorption spectroscopy and X-ray magnetic circular dichroism confirmed that the Mn 2+ ions substitute into the tetrahedrally coordinated sites. The magnetization measurement revealed that all of these nanowires exhibited room-temperature ferromagnetic behaviors, most significantly for the straight nanowires grown with the [101̄0] direction, having x = 0.02−0.03.