Induced Dichroism inn-Type Ge under High [111] Compression at 0°K

The absorption of polarized electromagnetic waves at 0°K in the wavelength region from 540 μ to 1.84 cm in $n$-type Ge subjected to high uniaxial [111] compression is investigated theoretically. The model of a direct absorption process, i.e., the photon-induced transitions of electrons between the ground states of donors, is applied. Dichroism appears as a result of the anisotropy of the ground-state wave functions of electrons on the donors. The integral formulas for the absorption coefficients for waves polarized in the planes parallel and perpendicular to the [111] direction in the crystal are derived, and the numerical results are presented. The dichroic ratio and the range of validity of our results are discussed. Concentrations of donors up to 6×${10}^{15}$ ${\mathrm{cm}}^{-3\mathrm{}}$ and compensations up to 0.2 are considered. Absorption coefficients up to the order of 1 ${\mathrm{cm}}^{-1\mathrm{}}$ and dichroic ratios up to about 10 are obtained.