Background doping as well as intentional doping using nitrogen and trimethylaluminum have been investigated for 4H-SiC epitaxy on offcut Si face, C face, and a-axis substrates over a wide range of C:Si ratio. Smooth morphology can be obtained at a C:Si ratio of 2.0 on a-axis substrates but not on Si or C face material. Background doping levels of <1 × 1015 cm-3 were achieved on a-axis and Si face material. Nitrogen incorporated much more efficiently on C face and a-axis as compared to Si face. Aluminum incorporated most efficiently on Si face and least efficiently on C face. Both of the above dopant incorporation trends were most pronounced at high C:Si ratios and were small or virtually absent at low C:Si ratios.