For epitaxy of GaN on 3C-SiC/Si substrates, optimization of growth temperature of AlN interlayers (ILs) was performed. With a proper growth condition of AlN IL crack-free 3.5 mu m thick GaN layer was realized by multiple AlN ILs on 3C-SiC/Si (1 1 1) substrate. The distribution of (DX)-X-0 peak position in low temperature cathodoluminescence spectra was mapped to investigate the stress in as-grown wafer. An increase of tensile stress was found in the top GaN layers above AlN ILs. Cross-sectional transmission electron microscopy images confirmed that AlN ILs could induce compressive stress and reduce threading dislocations in the GaN epilayer grown on 3C-SiC/Si. The reduction of dislocations should account for the part of incremental tensile stress revealed by the inhomogeneous distribution of luminescence. (C) 2012 Elsevier B.V. All rights reserved.