Far-Infrared Magnetoplasma Absorption due to Electron-Hole Drops in Germanium

Far-infrared magnetoplasma absorption due to electron-hole drops in pure germanium is observed in a transmission measurement for the wavelength 337µmi (HCN laser) and 119µm (H 2 O laser). Analysis is made in terms of Mie's light scattering theory, yielding the density of electron-hole pairs, the relaxation time in the drop and a strong frequency dependence of the latter. The values obtained from Mie's scattering theory are n d ∼9×10 16 cm -3 near 39 kOe, 1/τ∼5×10 11 and 6×10 11 sec -1 for 337µm at 1.9 and 4.2 K, respectively, and 10 12 ∼10 13 sec -1 for 119µm between 1.9 and 4.2 K.