Thin films of GaN have been deposited at relatively low growth temperatures by remote plasma-enhanced chemical-vapor deposition (RPECVD), using a plasma excited NH3, and trimethylgallium (TMG), injected downstream from the plasma. The activation energy for GaN growth has been tentatively assigned to the dissociation of NH groups as the primary N-atom precursors in the surface reaction with adsorbed TMG, or TMG fragments. At high He flow rates, an abrupt increase in the growth rate is observed and corresponds to a change in the reaction mechanism attributed to the formation of atomic N. X-ray diffraction reveals an increased tendency to ordered growth in the 〈0001〉 direction with increasing growth temperature, He flow rate, and rf plasma power. Infrared spectra show the fundamental lattice mode of GaN at 530 cm−1 without evidence for vibrational modes of hydrocarbon groups.