Gaydar A. Investigation of electron gas excitations in the crystals of germanium by inelastic light scattering

Object of investigation: excitations of free carriers and light scattering in uncompressed and uniaxially compressed crystals of p-Ge. Aim: to study the feature of unscreened single-particle and collective excitations in crystals with degenerate energy spectrum of carriers. Methods: measurements of spectra and polarization properties of inelastic light scattering, electroconductivity and Hall effect, numerical computation. Main results: experimental confirmation for the existing of new type of unscreened single-particle excitation in the crystals with degenerate energy spectrum of carriers, namely fluctuations of total momentum of carriers, has been obtained. The non-standard character of plasma frequency dependence on carrier concentration and assymmetrical shape of plasmon line have been founded. It was shown that this features are caused by intersubband transitions of carriers. Infrared Raman scattering due to the intersubband transitions between decoupled subbands in uniaxially crystals of p-Ge hasbeen studied and the change of the plasmon frequency under a uniaxially stress was observed. .