In sophisticated semiconductor devices, the defect rate that may typically be associated with the provision of a silicon/germanium material in the active region of P-channel transistors may be significantly decreased by incorporating a carbon species prior to or during the selective epitaxial growth of the silicon/germanium material. In some embodiments, the carbon species may be incorporated during the selective growth process, while in other cases an ion implantation process may be used. In this case, superior strain conditions may also be obtained in N-channel transistors.