Abstract
In this work the calibration of the directional Raman strain shift coefficient for tensile strained Ge microstructures is reported. The strain shift coefficient is retrieved from micro-Raman spectroscopy measurements in combination with absolute strain measurements from x-ray diffraction using focused synchrotron radiation. The results are used to fit the phonon deformation potentials. A linear dependence of the phonon deformation potentials p and q is revealed. The method can be extended to provide strain calibration of Raman experiments also in other material system.
Highlights
Until recently, strain engineering in the SiGe material system mainly concentrated on the improvement of electronic properties in tensile strained Si and compressively strained SiGe regions
Extending the approach to tensile strained Ge might enable a major breakthrough for the optical properties: tensile strain is predicted to revert the band structure of Ge from indirect to direct gap transitions which allows light emission and brings optical components integrated with Si technology within reach
Determined Raman strain shifts and absolute x-ray diffraction (XRD) strain values have been used in a novel fitting approach to fit phonon deformation potentials (PDPs)
Summary
Strain engineering in the SiGe material system mainly concentrated on the improvement of electronic properties in tensile strained Si and compressively strained SiGe regions. Extending the approach to tensile strained Ge might enable a major breakthrough for the optical properties: tensile strain is predicted to revert the band structure of Ge from indirect to direct gap transitions which allows light emission and brings optical components integrated with Si technology within reach. Different concepts have been used to realize tensile Ge [1,2,3], often based on microstructuring.
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