We report on the growth and characterization of cubic InGaN epilayers on two different types of substrates: GaAs (0 0 1) and 3C-SiC (0 0 1). The films are grown by RF plasma-assisted molecular beam epitaxy (MBE). The crystalline quality and state of stress in these films were assessed by performing Raman scattering and X-ray diffraction experiments. Both types of measurements complement one another as techniques to determine crystalline quality and the state of biaxial strain present in the alloy layers. Our experiments show that, for the same In molar fraction, samples deposited on SiC Substrates are more uniformly strained and have better crystallinity than those deposited on GaAs Substrates. (c) 2005 Elsevier B.V. All rights reserved.