Effect of the addition of silicon on the properties of germanium single crystals for IR optics

Homogeneous Sb-doped single crystals of Ge–Si solid solutions are grown with a silicon content of 0.2 to 0.8 at %. The optical absorption of single crystals with a resistivity of (2–3) $\Omega$ cm is studied by IR Fourier spectroscopy at a wavelength of 10.6 $\mu$m in the temperature range from 25 to 60$^{\circ}$C. It is found that the introduction of silicon into antimony-doped germanium improves the temperature stability of the optical properties of the crystals.