AlGaN films grown on trenched sapphire substrates using a low-temperature GaNP buffer layer by MOCVD

A technique has been developed to grow low-dislocation-density AlGaN films in this paper. The AlGaN film is laterally overgrown on a trenched sapphire substrate with a low-temperature (LT) GaNP buffer layer by metalorganic chemical vapour deposition (MOCVD). The optical charactertics and microstructure of the AlGaN films have been invesigated by means of cathodoluminescence (CL), high-resolution X-ray diffraction (HRXRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. It is shown that the dislocation densities in the Al0.07Ga0.93N film are reduced to 8.7 x 108 cm–2 (by CL) and 2.7 x 109 cm–2 (by TEM) in the whole trenched sapphire, and 4.0 x 108 cm–2 (by CL) and 1.3 x 109 cm–2 (by TEM) in the trenched area. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)