The use of Raman spectroscopy to characterize strain in strained Si and strained SiGe has been widely accepted. To use Raman spectroscopy for quantitative biaxial strain measurements, the strain shift coefficient for Si-Si vibration from strained Si (b StSi Si{Si ) and strained SiGe (b StSiGe Si{Si ) must be known. So far, b StSiGe Si{Si is commonly used to calculate strain in strained Si, which may result in inaccurate strain values. In this work, we report the first direct measurement of b StSi Si{Si by correlating highresolution X-ray diffraction and Raman spectroscopy, which yields a measured value of À784 AE 4 cm À1 . We also show that the strain shift coefficient of SiGe, b StSiGe Si{Si , is a strong function of Ge concentration (x), and follows the empirical relation: b ¼ À773:9 À 897:7x for x < 0:35.

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