Simple route to fabricate nanowire-assembled 3D AlGaN nanourchins by chemical vapour deposition

Large-scale nanowire-assembled three-dimensional (3D) AlGaN nanourchins are synthesized under various growth conditions via a facile chemical vapour deposition (CVD) method. Characterizations of the morphology, microstructure, and crystalline phase of the as-prepared products reveal that the urchin-like AlGaN nanostructures with a hexagonal wurtzite structure are pure, and have a homogenous composition distribution, and also that they are composed of an assembly of nanowires with sharp tips and lengths of 1-2.5 µm. Effects of growth temperature, growth time, and introduction of NH3 at different substrate temperatures (Tsub) on the growth of the AlGaN nanostructures are systematically investigated. The investigation results show that Tsub is a crucial factor influencing the formation of the 3D AlGaN nanourchins, and an increase in growth temperature results in a variation of their crystal quality and size. The growth mechanism of the urchin-like AlGaN nanostructures is discussed on the basis of the morphological evolution of the samples obtained under different growth conditions. The unique optical properties of the AlGaN nanostructures as evidenced by the photoluminescence spectra suggest the potential of their applicability in nanoscale optoelectronics.