Effect of temperature on GaN nanowires fabricated via thermal heating of GaN powders

GaN nanowires have been successfully synthesized by heating GaN powders under flowing ammonia gas in a temperature range of 950–1050 °C. The nanowire morphology was changed with varying temperature, and higher temperature favored thinner nanowires. The growth mechanisms of GaN nanowires at 950 °C included a vapor-liquid-solid process. The photoluminescence (PL) spectra of the samples commonly exhibited violet to yellow emission, whereas red emission occurred preferentially in samples synthesized at lower temperature. We have discussed the possible mechanisms by which growth temperature affected the nanowire morphology and PL spectrum.