We investigate the thermal stability of pseudomorphically strained Si: C layer using high resolution x-ray diffraction (HRXRD) and Fourier transform infrared (FTIR) spectroscopy. Far below beta-SiC precipitation threshold, almost complete strain relaxation is found without significant substitutional carbon (C(sub)) loss. FTIR shows the strain relaxation is related to volume compensation by C(sub)-interstitial complex formation through oxidation injection of interstitial. By multilayer HRXRD kinematical simulation, we find correlation of the enhanced strain relaxation to P distribution, implying P's role as additional interstitial promoter during postannealing treatment. We relate our findings to recent reports on strain relaxation issues in Si:C devices fabrication. (C) 2011 American Institute of Physics. [doi:10.1063/1.3572339]
