Poplavs'kyj D. Electron-phonon interaction in systems with localisation of charge carriers

This thesis is devoted to studies of the processes of electron-phonon interaction in the system with strongly-localised carriers (intermediately-doped n-Ge) and in the two-dimensional electron gas, where the effects of weak localisation are present (delta-doped GaAs:Si). From the results of galvanic and acoustic studies on intermediately doped n-Ge it is shown that there is an energy gap of the order of several meV which monotonically changes with uniaxial stress applied along <111> direction. A model of impurity D- band is proposed; the model adequately fits the results of experiments and allows estimating the parameters of the band. The results of galvanomagnetic measurements in samples of delta-GaAs:Si allowed to determine the character of energy losses of the electron gas and to estimate the applicability of different approaches to determine the temperature of carriers (and their energy losses) in the system. Results of studies of phonon-induced conductivity are reliably explained on the basis of t he proposed model of "destruction" of weak localisation of charge carriers caused by absorption of acoustic phonon energy by electron gas. Detailed calculations of electron-phonon interaction taking into account screening effects were carried out and allowed to study the processes of phonon absorption by different sub-bands and under different conditions of phonon incidence onto the two-dimensional layer.