Doping forms the second corner of the epi trilemma. Higher doping concentration is desirable for MBC. Higher doping leads to more Phosphorus in the epitaxial plug, which in turn leads to early faceting and therefore quick selfsaturation of epitaxial growth. Fig VI shows how the self-saturating epi height changes with lattice strain. Lower lattice strain makes the epitaxial plug highly stable thereby delaying the formation of facets. The lattice strain is directly related to the lattice mismatch between the epitaxial plug and the templating substrate. Therefore, to lower the strain, we must get the lattice constants as closely matched as possible. In order for that to happen, we will have to lower the amount of doping in the epitaxial plug.