Structural and optical properties of GaN films grown by the direct reaction of Ga and NH3 in a CVD reactor

GaN films were grown on sapphire using a direct reaction of metallic galliu m with ammonia in a conventional RF induction heated chemical-vapor-deposit ion (CVD) reactor. The crystal and optical qualities of the GaN improved si gnificantly by increasing the distance between the sapphire substrate and G a source. For thick GaN films grown at a position 3.5 cm away from the Ga s ource, the FWHM for the (0 0 0 2) peak of the XRD curve was about 684 arcse c which is the best value obtained in this work, and the room-temperature p hotoluminescence spectrum exhibited a strong band-edge luminescence at 3.41 4 eV. The correlation of structural and optical properties of the GaN films manifested in deep level yellow luminescence having a close relation to (1 0 (1) over bar 0)and (10 (1) over bar 1) planes developed during the growth , it was speculated that the emission of YL is mainly due to the formation of deep gap state in the band gap by Ga vacancy and impurities trapped at d omain boundary with (10 (1) over bar 0) and (10 (1) over bar 1) atomic face ts. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.