Synthesis, Raman scattering, and infrared spectra of large-scale GaN nanorods

Large quantities of gallium-nitride nanorods have been synthesized by using direct reaction of metal gallium vapor with flowing ammonia at 970degreesC in a quartz tube. The nanorods have been confirmed as crystalline wurtzite GaN by powder X-ray diffraction and selected area electronic diffraction. Transmission electron microscopy and scanning electron microscopy reveal that the nanorods are straight and uniform, with diameters ranging from 40 to 150 nm and lengths up to hundreds of micrometers. Raman spectroscopy yields narrow peaks responding only to the modes allowed for the wurtzite structure. And phonon modes investigated by infrared spectra show the frequency of both TO and LO phonons at 563 and 728 cm(-1), respectively. These results agree well with the theoretical study. The growth mechanism is briefly discussed. (C) 2002 Elsevier Science B.V. All rights reserved.