Structural evolution of AlN nano-structures: Nanotips and nanorods

Aluminum nitride (AlN) nanostructures were prepared using thermal chemical vapour deposition process. At growth temperatures of 950 °C, AlN nanotips with apex diameters of 10 nm, base diameters of ∼100 nm, and length of ∼2000 nm were obtained. Whereas when the growth temperature was 1200 °C, we obtained shorter and thicker AlN nanorods. Compelling microscopic evidences were obtained to show that stacked AlN platelets of diminishing size formed the building blocks for the nanotips. A reducing Ehrlich-Schwoebel barrier introduced into a diffusion mediated growth model explains the formation of AlN nanorods at increasing growth temperatures.