We describe a new GaN film growth method employing a supersonic jet of nitrogen atoms and a gallium effusion cell. The nitrogen atoms were generated by exciting a 1% nitrogen in helium mixture with a radio frequency discharge. X-ray diffraction and in situ reflection high-energy electron diffraction indicate that GaN films grown on sapphire (0001) were single crystalline and epitaxial with a rough surface morphology. A GaN growth rate of approximately 0.65 μm/h was measured, independent of substrate temperature over the range of 600–750 °C. However, the crystalline quality of the film increases markedly with increasing wafer temperature.