In this work, we demonstrate substitutional phosphorus concentration as high as 12 at.% in epitaxial silicon. It is observed that 10 at.% substitutional phosphorus doping is equivalent in tensile strain to incorporating 2.1 at.% substitutional carbon into the silicon lattice. Phosphorus doping of this order produces tensile strain levels suitable for n-channel metal-oxide semiconductor field-effect transistor uniaxial stressor applications. This work focuses on the experimental and theoretical analyses of phosphorus doped silicon based on high resolution X-ray rocking curves, secondary ion mass spectroscopy, Rutherford backscattering spectroscopy, and molecular dynamic modeling. (C) 2011 Elsevier B.V. All rights reserved.