INFRARED-SPECTROSCOPY OF STRAINED SI1-YCY ALLOYS SS-THAN-OR-EQUAL-TO-Y-LESS-THAN-OR-EQUAL-TO-0.015) GROWN ON SILICON

We have performed infrared absorption spectroscopy and X-ray diffracti on measurements on strained Si1-yCy layers grown by molecular beam epi taxy on Si substrates. Our experiments show that the formation of subs titutional carbon and the appearance of beta-SiC precipitates depend o n growth rate and growth temperature. Post-growth annealing experiment s at temperatures higher than 850 degrees C cause the formation of bet a-SiC precipitates accompanied by a decrease of substitutional carbon. The simulation of the X-ray data shows that substitutional carbon is lost mainly near the surface. Infrared absorption studies reveal that the loss is accompanied by the formation of beta-SiC precipitates in t he near-surface region. Post growth moderate annealing experiments bel ow 800 degrees C lead to a smaller linewidth for the carbon vibrationa l mode, indicating improved crystal quality.