The characterization of AlGaN nanowires prepared via chemical vapor deposition

AlGaN ternary alloys exhibit some superior properties due to their tunable direct band gap and make them widely used in the fabrication of electronic and optoelectronic devices. Here, we successfully synthesized AlGaN nanowires by chemical vapor deposition using Al powder, Ga droplet and ammonia as starting materials with Pd as catalyst under a moderate growth temperature. The role of Pd catalyst during the growth has been systematically studied. We found that not only the Pd catalyst is the key to the growth of AlGaN nanowires in large scale, but also the sizes of catalyst nanoparticles have an important effect on diameter distribution of nanowires. XRD and HRTEM measurements confirmed that the synthesized AlGaN nanowires are the wurtzite structure and grown along [001] direction. The growth time and ammonia flow have important influence on the morphology of the AlGaN nanostructures. Based on the evolution of the nanostructures, we verified that the growth of the AlGaN nanostructures are affected by both VLS and VS mechanism and explained the growth process.