Syringe-shaped GaN nanorods are synthesized on Si(111) substrates by annealing sputtered Ga2O3/BN films under flowing ammonia at temperature of 950° C. Most of the nanorods consist of a main rod and a top needle, looking like a syringe. X-ray diffraction and selected-area electron diffraction confirm that the syringe-shaped nanorods are hexagonal wurtzite GaN. Scanning electron microscopy and high-resolution transmission electron microscopy reveal that these nanorods are as long as several micrometres, with diameters ranging from 100 to 300 nm. In addition to the BN intermediate layer, the proper annealing temperature has been demonstrated to be a crucial factor for the growth of syringe-shaped nanorods by this method.