Optical Properties of Single-Crystal Germanium in the THz Range.

The transmission of intrinsic, antimony-doped, and gallium-doped Ge single crystals in the THz spectral range have been experimentally investigated. It is shown that the attenuation coefficient of intrinsic germanium in the range of 160‒220 μm is at a level of ~0.5 cm‒1, a value comparable with that for silicon. The free-carrier absorption cross sections of silicon and germanium are significantly different, which may be caused by the difference in the mechanisms of carrier–phonon interaction in these materials. [ABSTRACT FROM AUTHOR]