Large-scale synthesis of GaN nanorods and their photoluminescence

Large quantities of gallium nitride (GaN) nanorods have been synthesized via direct reaction of metallic gallium vapor with flowing ammonia at 970 °C in a quartz tube. The nanorods have been confirmed as crystalline wurzite GaN by powder X-ray diffraction, selected-area electron diffraction and X-ray photoelectron spectrometry. Transmission electron microscopy and scanning electron microscopy reveal that the nanorods are straight and uniform, with diameters ranging from 40 nm to 150 nm and lengths up to hundreds of micrometers. The growth mechanism is discussed briefly. Photoluminescence measurements on bulk GaN nanorods at room temperature show two strong peaks at 377 nm (3.28 eV) and 360 nm (3.44 eV) attributed to the zero-phonon donor-acceptor pair transition and the donor-bound exciton, respectively.