Quantification of substitutional carbon loss from Si_0.998C _0.002 due to silicon self-interstitial injection during oxidation

The empirical reaction of substitutional carbon with silicon self-interstitials in Si_0.998C_0.002 layers pseudomorphically grown on Si (100) substrates has been quantified at 850°C. During annealing of a sample with a thin Si_0.998C_0.002 layer capped with a thin crystalline silicon layer, in either oxygen or nitrogen ambient, carbon diffuses from the surface edge of the Si_0.998C _0.002 layer towards and out of the silicon surface. The extra number of carbon atoms lost during oxidation is found equal to the number of silicon interstitials injected by the oxidation process, strongly suggesting that each substitutional carbon reacts with a single self-interstitial to form a mobile interstitial carbon, whereby it diffuses to the surface. The mechanism appears the same in Si_1-x-yGe_xC_y and Si _1-xC_x films.