Growth of AlN nanostructures by a rapid thermal process

Aluminum nitride nanorods were grown during rapid thermal annealing of multi-layered Al₂S₃ /BaS thin films. Depending on the thickness ratio between the BaS and Al₂S₃ layers, nanowires or straight nanorods were obtained. Typical dimensions for the nanorods were a diameter in the range of 50-100 nm and a length of 2-5 μm. The nanostructures are formed upon annealing at a relatively low temperature of 900 ^°C when aluminum evaporates from the thin film, but remains trapped between the thin film surface and the Si wafer, which is used as a support during the annealing. The nitrogen is provided by N₂ gas flushed through the annealing chamber. High-resolution transmission electron microscopy showed crystalline, wurtzite-structured AlN nanorods. The growth mechanism in terms of thin film composition, annealing parameters and the role of catalysts is discussed.