Controllable synthesis of AlN nanostructures and their photoluminescence

AlN nanostructures with controllable morphologies are synthesized on a Si substrate with an Al particle layer as a self-catalyst via a chemical vapor deposition (CVD) technique under atmospheric pressure. The effects of temperature, NH3 flow and the gas entrance procedure on the morphologies are investigated. Especially, among these nanostructures, the AlN nanowhiskers exhibit a high aspect ratio, which is about one order of magnitude larger than that of other AlN nanostructures. A mechanism for controlled morphology is proposed based on the self-catalyzed nucleation and the diffusion process of Al adatoms on the surface under different reaction conditions (either Al-rich or N-rich). Moreover, the AlN nanostructures exhibit intense photoluminescence and this can be tuned through the size and morphology of the nanostructures.