The microstructural characteristics of 300 mum thick freestanding 3C-SiC wafers, provided by HOYA, were studied by transmission electron microscopy. The observed defects were mainly stacking faults (SFs), microtwins and inversion domain boundaries (IDBs). The defect density is reduced fast from the SiC/Si interface up to the first 20 mum, and then it remains constant up to the surface, suggesting a defect growth and elimination mechanism. At the uppermost part of the film the distribution of the SFs is very inhomogeneous; large zones were completely free of SFs with the SFs mainly concentrating in areas where IDBs exist and their density was lower by more than one order of magnitude than the SFs. 3C-SiC 40 mum thick layers were grown on the wafers by sublimation epitaxy. Optical micrographs of these layers exhibit macro-features different from the substrate, but still indicating large bands of SFs. (C) 2003 Elsevier B.V. All rights reserved.