Controllable synthesis of AlN nanostructures and their photoluminescence

Abstract

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.