A systematic n-type doping study has been performed on 4H- and 6H-SiC epilayers grown at high growth rate using chloride-based CVD. The effect of temperature, pressure, growth rate, C/Si and Cl/Si ratios and dopant flow on the incorporation of the nitrogen and phosphorus donor atoms has been investigated. It is found that the effect of the C/Si ratio on the incorporation of nitrogen or phosphorus atoms is similar to what has been reported for the standard low growth rate process without addition of chlorine. The Cl/Si ratio seems to affect the nitrogen incorporation at growth rates higher than 65 mu m/h. The doping concentration is stable against variations in growth rate, growth pressure and growth temperature for the nitrogen-doped layers. (C) 2008 Elsevier B.V. All rights reserved.