A process optimization of the growth of SiC epilayers on 4° 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 μm thick n-type doped epitaxial layers on 75 mm diameter wafers is demonstrated as well as that of 20 μm thick layer. The optimized process was then transferred to a chloride-based process and a growth rate 28 μm/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.