The evolution of surface morphology and film stress during metalorganic chemical vapor deposition (MOCVD) growth of InN on sapphire substrates was investigated. In situ stress measurements were carried out using a multi-beam optical stress sensor system, which measures changes in sample curvature during film deposition. Growth of InN on a low temperature AlN buffer layer on sapphire was observed to occur via island nucleation and coalescence. A constant tensile growth stress of approximately 0.2 GPa was measured in the InN films for thickness < 200 nm. For films thicker than approximately 200 nm, growth continued at almost zero stress. This corresponded to the point at which film delamination was observed to occur at growth temperature. This undesirable stress relief mechanism limits the thickness of InN layers that were grown by MOCVD on sapphire using an AIN buffer layer. (C) 2004 Elsevier B.V. All rights reserved.