A process optimization of the growth of silicon carbide (SiC) epilayers on 4 degrees off-axis 4H-SiC substrates is reported. Process parameters such as growth temperature, C/Si ratio and temperature ramp-up conditions are optimized for the standard non-chlorinated growth in order to grow smooth epilayers without step bunching and triangular defects. The growth of 6-mu m-thick n-type-cloped epitaxial layers on 75-mm-diameter wafers is demonstrated as well as that of 20-mu m-thick layer. The optimized process was then transferred to a chloride-based process and a growth rate of 28 mu m/h was achieved without morphology degradation. A low growth temperature and a low C/Si ratio are the key parameters to reduce both the step bunching and the formation of triangular defects. (C) 2009 Elsevier B.V. All rights reserved.