  Gallium nitride nanowires were grown on c-plane, r-plane and m-plane sapphire
substrates in a showerhead metalorganic chemical vapor deposition system using
nickel catalyst with trimethylgallium and ammonia as precursors. We studied the
influence of carrier gas, growth temperature, reactor pressure, reactant flow
rates and substrate orientation in order to obtain thin nanowires. The
nanowires grew along the <10-11> and <10-10> axes depending on the substrate
orientation. These nanowires were further characterized using x-ray
diffraction, electron microscopy, photoluminescence and Raman spectroscopy.
