Magneto-Optical Studies of Electron-Hole Drops in Germanium by Far-Infrared Lasers

Abstract

Far-infrared magnetoplasma absorption due to electron-hole drops in pure germanium is observed in laser transmission measurements for eleven wavelengths (84 to 513 μm). From the oscillatory behavior in short wavelength absorption, it is concluded that the carrier-pair density in the drop remains constant (2.2×10¹⁷ cm⁻³) up to 20 kOe and increases to 2.7×10¹⁷ cm⁻³ at 50 kOe after first decreasing to 2.0×10¹⁷ cm⁻³ at ∼25 kOe. The relaxation time in the drop is calculated from the linewidth of the peak of 337 μm absorption at ∼38 kOe and it has a temperature dependence of the form 1⁄τ=α+βT² with α=(2.1±0.1)×10¹¹ s⁻¹ and β=(1.2±0.1)×10¹⁰ deg⁻²s⁻¹. It is strongly suggested that carrier-carrier scattering is the dominant mechanism for the relaxation process in the electron-hole drop.