GaN was grown by metal organic chemical vapor deposition (MOCVD) on plain Si-on-insulator (SOI) substrates, and on SOI which was pre-patterned for lateral confined epitaxy (LCE), with square mesas, separated by dip trenches. It was found that GaN films grown on plain SOI exhibit reduced crack density. Moreover, using LCE on SOI substrates dramatically increases the crack-free area of the layer. Areas of 100 mum x 100 mum were grown completely crack free, and stress was released by strong bending of the GaN/Si/SiO2 composite islands. (C) 2002 Elsevier Science B.V. All rights reserved.