We investigate the effects of c-plane sapphire substrate misorientation angle on metalorganic chemical vapor deposition of GaN nucleation layers. The angle from (0001) c-plane sapphire was varied between 0.05degrees and 0.30degrees, tilted towards the m-plane axis. Structural and optical characterization techniques demonstrate an improvement of surface morphology and crystalline quality of GaN nucleation layers as the miscut angle approaches 0.30degrees. These results correlate well with our previous study of miscut angle on full light-emitting diode structures. (C) 2004 Elsevier B.V. All rights reserved.