Epitaxial growth of GaN films by pulse-mode hot-mesh chemical vapor deposition

Intermittent gas supplies for hot-mesh chemical vapor deposition (CVD) for the epitaxial growth of gallium nitride (GaN) films were investigated to improve film crystallinity and optical properties. The GaN films were deposited on SiC/Si(111) substrates using an alternating-source gas supply or an intermittent supply of source gases such as ammonia (NH₃) and trimethylgallium (TMG) in hot-mesh CVD after deposition of an aluminum nitride (AlN) buffer layer. The AlN layer was deposited using NH₃ and trimethylaluminum (TMA) on a SiC layer grown by carbonization of a Si substrate using propane (C₃H₈). GaN films were grown on the AlN layer by a reaction between NH_x radicals generated on a ruthenium (Ru)-coated tungsten (W) mesh and TMG molecules. After testing various gas supply modes, GaN films with good crystallinity and surface morphology were obtained using an intermittent supply of TMG and a continuous supply of NH₃ gas. An optimal interval for the TMG gas supply was also obtained for the apparatus employed.