Dielectric function spectra of strained and relaxed Si1−xGex alloys (x=0–0.25)

Abstract
Dielectric function spectra for strained and relaxed Si1−xGex alloys with x∼0.13 and 0.20 are presented in numerical form. The effect of strain is shown to cause a modification of the spectra in the E1 critical point region, resulting in a decrease in refractive index at 1.96 eV, amounting to 0.06 at x=0.22. The spectral dependence of the refractive index is presented for a series of strained layers. An overview is given of spectral databases and the single‐wavelength ellipsometry data available in the literature.