Determination of Raman Phonon Strain Shift Coefficient of Strained Silicon and Strained SiGe

摘要

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_(Si-Si)~(StSi)) and strained SiGe (b_(Si-Si)~(StSiGe)) must be known. So far, b_(Si-Si)~(StSiGe) 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_(Si-Si)~(StSi) by correlating high-resolution X-ray diffraction and Raman spectroscopy, which yields a measured value of -784 ± 4 cm~(-1). We also show that the strain shift coefficient of SiGe, b_(Si-Si)~(StSiGe), is a strong function of Ge concentration (x), and follows the empirical relation: b = -773.9 - 897.7x for x < 0.35.