Temperature dependence of strain–phonon coefficient in epitaxial Ge/Si(001): A comprehensive analysis. (26th February 2020) - Manganelli, C.L.
Abstract: We investigate the temperature dependence of the Ge Raman mode strain–phonon coefficient in Ge/Si heteroepitaxial layers. By analyzing the temperature‐dependent evolution of both the Raman Ge─Ge line and of the Ge lattice strain, we obtain a linear dependence of the strain–phonon coefficient as a function of temperature. Our findings provide an efficient method for capturing the temperature‐dependent strain relaxation mechanism in heteroepitaxial systems. Furthermore, we show that the rather large variability reported in the literature for the strain–phonon coefficient values might be due to the local heating of the sample due to the excitation laser used in μ‐Raman experiments. Abstract : The phonon strain–shift coefficient for heteroepitaxial Germanium layers are accurately determined via X‐ray diffraction and micro‐Raman spectroscopy in the temperature range 150–413 K. Thanks to a proper theoretical framework, interpretation of the data provides also the temperature dependence of the biaxial strain field. We find a linear dependence of the coefficient with the temperature, with slope −0.15 ± 0.03 cm −1 /K.