Optical properties

			Remarks	Referens
Dielectric constant (static)	Si (x=0)	11.7	300 K	Schaffler F. et al.(2001)
	Ge(x=1)	16.2	300 K
	Si1-xGex	11.7 + 4.5x	300 K
Infrared refractive index n(λ)	Si1-xGex	n 3.42 + 0.37x + 0.22 x2	300K	Schaffler F. et al.(2001)
	Si (x=0)	n = 3.42	300K	see Si. Refractive index
		n = 3.38(1 + 3.9·10-5·T)	77K < T < 400 K
	Ge(x=1)	n = 4.0	300K	see Ge. Refractive index
Radiative recombination coefficient	Si (x=0)	1.1 x 10-14 cm3 s-1	300 K	see Si. Optical properties
	Ge(x=1)	6.4 x 10-14 cm3 s-1	300 K	see Ge. Optical properties
Optical photon energy	Si1-xGex	(63 - 8.7x) meV	Si - Si, 300 K	Schaffler F. et al.(2001)
		(35.+2.0x) meV	Ge-Ge, 300 K
		50 meV	Si-Ge, 300 K see also Si1-xGex. Optical phonon Raman signals
	Si (x=0)	63 meV	300 K	see Si. Optical properties
	Ge(x=1)	37 meV	300 K	see Ge. Optical properties

	Si. Dispersion curves for acoustic and optical phonons. Dolling (1963) and Tubino et al. (1972)
	Ge. Dispersion curves for acoustic and optical phonons. Weber (1977)

Si1-xGex. Optical phonon Raman signals associated with local Si-Si, Si-Ge and Ge-Ge modes vs. composition Alonso & Winer (1989)

	Si1-xGex (bulk). Refractive index n vs. energy range between 0.5 and 1.4 eV. Refractive index n in the energy range between 0.5 and 1.4 eV Humlicek (1995)
	Si1-xGex (bulk alloys). Refractive index n vs. energy range between 1.5 and 5.5 eV. Lines correspond (left to right) to composition values of x = 1 (Ge), 0.915, 0.831, 0.75, 0.635, 0.513, 0.389, 0.218, 0 (Si) Humlicek et al. (1989)
	Si1-xGex Reflectivity vs. photon energy in the energy range 0-13 eV Reflectivity vs. photon energy in the energy range 0-13 eV Schmidt (1968)

	Si1-xGex (bulk alloys).The absorption coefficient α vs. energy range between 0.5 and 1.4 eV with x varying by increments of 0.1 between Ge (x = 1) and Si (x = 0). Vertical arrows mark the respective indirect band gaps Humlicek (1995)
	Si1-xGex The absorption coefficient vs. energy range between 1.5 and 5.5 eV for different compositions Lines correspond (left to right) to composition values of x = 1 (Ge), 0.915, 0.831, 0.75, 0.635, 0.513, 0.389, 0.218, 0 (Si). Humlicek et al. (1989)

	Si1-xGex Free electron absorption vs. wavelength at different doping levels for n-Si (x = 0). 300 K. Electron concentrations :     1 -- 1.4 x 1016 cm-3;     2 -- 2.8 x 1016 cm-3;     3 -- 1.7 x 1017 cm-3;     4 -- 3.2 x 1017 cm-3;     5 -- 6.1 x 1018 cm-3;     6 -- 1.0 x 1019 cm-3. Spitzer & Fan (1957)
	Si1-xGex. Free hole absorption vs. wavelength at different doping levels for p-Si (x = 0) 300 K. Hole concentrations :     1 -- 4.6 x 1017 cm-3;     2 -- 1.4 x 1018 cm-3;     3 -- 2.5 x 1018 cm-3;     4 -- 1.68 x 1019 cm-3. Hara & Nishi (1966)
	Si1-xGex. Free electron absorption vs. wavelength at different doping levels for n-Ge (x = 1). 300 K. Electron concentrations :     1 -- 8.0 x 1017 cm-3;     2 -- 4.8 x 1018 cm-3;     3 -- 1.35 x 1019 cm-3;     4 -- 1.8 x 1019 cm-3;     5 -- 3.6 x 1019 cm-3; Fistul (1967)
	Si1-xGex. Free hole absorption vs. wavelength at different doping levels for p-Ge (x = 1). 300 K. Hole concentrations :     1 -- 7.3 x 1015 cm-3;     2 -- 1.6 x 1016 cm-3;     3 -- 6.0 x 1016 cm-3;     4 -- 1.9 x 1017 cm-3;     5 -- 1.2 x 1018 cm-3;     6 -- 1.0 x 1019 cm-3. Ukhanov (1966), Vasilyeva et al (1967)