Thermal stability of the properties of germanium crystals for IR optics

Abstract

Both Sb-doped Germanium and Ge-Si solid solution single crystals with resistivity from 1.5 to 7 Ω·cm were grown using the Czochralski method. The optical transmission of single crystals and the stability of their optical properties were studied by infrared Fourier spectroscopy at a wavelength of 10.6 μm and temperature range from 25 to 60 °C. It was found that decreasing the background impurities concentration leads to the reduction of the infrared absorption at room temperature while not affecting the thermal stability of the optical properties. Thermal stability of the optical properties of Sb-doped germanium single crystals increases by adding from 0.2 to 0.8 at % of silicon.