Quantum confinement of excitons in dendrite-like GaN nanowires

Dendrite-like GaN nanowires have been grown by direct reaction of gallium metal with ammonia without any catalyst in a simple grinding-mediated two-step process, the second step being annealing of the as-synthesized GaN powder at 800°C. The samples have been characterized by x-ray diffractometry, transmission electron microscopy (TEM), and photoluminescence (PL). TEM results show that many of the synthesized nanowires are of diameters less than the Bohr exciton radius of GaN. A large blue shift of the excitonic peak in the photoluminescence (PL) spectra indicates quantum confinement of the carriers. These results are significant for the growth of dendrite-like GaN nanowires with a small aspect ratio.