Crystallography and cathodoluminescence of ultra-long GaN nanowires

Abstract

Ultra-long GaN nanowires have been synthesized via a simple thermal evaporation process by heating mixed GaN and Ga2O3 powders in a conventional resistance furnace under ammonia gas at 1150 °C. The average length of GaN nanowires is estimated to be more than 100 μm after 30-min growth, corresponding to a fast growth rate of more than 200 μm/h. Scanning electron microscope (SEM) observation indicated that the diameter of GaN nanowires was rather uniform along the growth direction and in the range of 100-200 nm. X-ray diffraction (XRD) and transmission electron microscope (TEM) measurements confirmed that the GaN nanowires are crystalline wurtzite-type hexagonal structure. Room-temperature cathodoluminescence (CL) measurement indicated that an obvious red-shift of the near band-edge emission peak centered at 414 nm of the ultra-long GaN nanowires and a wide shoulder in the range of 600-700 nm were observed. Possible reasons responsible for the red-shift of the near band-edge emission of the ultra-long GaN nanowires was discussed. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.