A simple quantitative model for the surface adsorption of nitrogen has been developed to simulate the doping incorporation in intentionally doped 4H-SiC samples during epitaxial growth. Different reaction schemes are necessary for the two faces of SiC. The differences are discussed, and implications to the necessary model adjustments are stressed. The simulations, are validated by experimental values for a large number of different process parameters with good agreement. (C) 2003 Elsevier Science B.V. All rights reserved.