Effect of thermal annealing on the Raman spectrum of Si1−xGex grown on Si

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Abstract
The effect of thermal annealing on the Raman spectrum of Si1−xGex grown on Si was investigated in the temperature range of 800–1100 °C on three samples having Ge contents x of 0.2 and thicknesses of 0.08, 0.16, and 0.40 μm. For annealing below 900 °C, the stress relaxation played an important role on the Raman shift. The degree of the stress relaxation in a dislocation free sample was smaller than that in a sample with partially relaxed stress. Stress was not completely relaxed in any of our samples after annealing. For annealing above 900 °C, diffusion strongly affected the Raman shift and the spectral lineshape. The critical thickness was close to 0.08 μm.