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 Si_0.8Ge_0.2 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°C 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.