PHONON STRAIN-SHIFT COEFFICIENTS OF SI1-XGEX GROWN ON GE(001)

High germanium content Si1-xGex alloys have been grown pseudomorphical ly at 400 degrees C on Ge (001) by molecular-beam epitaxy. The germani um fraction determined using x-ray diffraction measurements (x=0.8) is in good agreement with the value obtained with in situ x-ray photoemi ssion results and vapor flux control. Combining Raman spectroscopy res ults and the epilayer stress value obtained by x-ray diffraction, we h ave determined the strain-shift coefficient (b) for each main Raman li ne (Ge-Ge, Si-Ge, and Si-Si). The variation of b is similar to the Gru neisen parameter (gamma) alloy variation, i.e., b and gamma values inc rease with increasing chemical disorder. The use of Raman scattering a s a direct tool to determine the strain is discussed. The temperature dependence of the phonon frequencies has also been studied in the rang e from 300-5 K.