GaN films were grown on Si(111) substrates at 400–800 °C using a single precursor diethylazidogallium methylhydrazine adduct, Et2(N3)Ga∙MeHNNH2, under high-vacuum conditions (5×10-6 Torr). The chemical composition, crystalline structure, and morphology of the deposited films were investigated by x-ray photoelectron spectroscopy, x-ray diffraction, double crystal x-ray diffraction, x-ray pole figure analysis, and scanning electron microscopy. The results show that high-quality h-GaN films with correct stoichiometry can be deposited on Si(111) at a relatively low temperature by chemical-beam deposition (CBD). Room-temperature photoluminescence measurements have been performed to evaluate the optical properties of the GaN films. The single precursor Et2(N3)Ga∙MeHNNH2 has been found suitable for the CBD of GaN thin films on Si substrates. © 2004 American Vacuum Society.