Schematic of (a) SiGe virtual substrate and (b) of a strained-Si layer on an ultrathin SiGe buffer including a buried part with point defect supersaturation at low temperature initiating the early relaxation.
Fitting of Ge–Ge band with asymmetrical [Eq. (1)] and Gaussian functions. The example of the best choice for and points used in Eq. (1) is also shown.
(a) Raman spectra for SiGe/Si samples with and different Ge content. (b) Raman spectra for strained SiGe/Si samples with different Ge content.
(a) Si–Si, (b) Si–Ge, and (c) Ge–Ge Raman peak position vs Ge content determined by HRXRD.
Raman shift in (a) Si–Si, (b) Si–Ge, and (c) Ge–Ge peak as a function of Ge content. Dotted lines correspond to the dependence of vs Ge content for fully strained samples and dashed line for fully relaxed samples.
Deviation of Ge content obtained from Raman and XRD data vs Ge content determined by HRXRD measurements.
The various baselines that can be chosen in calculating the intensities of the Si–Si, Si–Ge, and Ge–Ge modes. The black dashed line indicates the baselines used in this work.
Intensities ratio vs Ge content, x from the experimental data (symbols) and (a) from Eq. (16) at (gray line) and (black line) and (b) from Eq. (17) at (gray line) and (black line).
(a) Raman spectra of sample 1797, 1669, 1799, and 1800 with increasing Ge content collected at 514 nm excitation wavelength. The strained-Si peak is observed between the Si substrate peak at and the Si–Si band from the SiGe layer. (b) Fitting of Raman spectrum for sample 1797 with three Lorentzian functions.
Raman spectra for samples 1797, 1669, and 1799 collected at (a) 488 nm excitation and (b) at 325 nm excitation wavelength.
Nominal thickness and composition for samples with s-Si on SiGe virtual substrate [related to structures from Fig. 1(b)].
The calculated Ge concentration and relaxation factor for samples measured by XRD and Raman techniques [related to structures from Fig. 1(a)].
Shift in Si–Si peak , stress, and strain for s-Si layer obtained from Raman spectra at different excitation wavelengths [related to structures from Fig. 1(b)].
Ge content, relaxation factor, and strain in SiGe layers obtained from XRD and Raman measurements [related to structures from Fig. 1(b)].
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