Effect of thermal processing on strain relaxation and interdiffusion in Si/SiGe heterostructures studied using Raman spectroscopy

The effect of thermal annealing on Si/SiGe heterostructures is studied using Raman spectroscopy. The structures consisted of Si on relaxed Si0.8Ge0.2 where the top Si thickness was 20-30 nm. Micro-Raman spectroscopy with 488 nm incident radiation revealed no significant shift in the strained Si peak position with thermal annealing at temperatures up to 1100 degreesC for 30 s. However, the intensity of the Si peak was systematically reduced with increasing thermal processing, a result which is attributed to interdiffusion at the Si/SiGe interface resulting in an apparent thinning of the Si cap layer. (C) 2001 American Institute of Physics.