Tymochko M. Galvanomagnetic phenomena in CdMnHgTe, Ge, Si crystals modified by ultrasound and gamma-irradiation

The thesis is dealt with the investigation of characteristics of the charge carriers transport phenomena in the bulk semiconductor solid solutions MnHgTe, CdMnHgTe and Ge, Si crystals; it clarifies the dominant mechanisms of ultrasonic (US) and gamma-irradiation influence on crystals with different defect structure and proposes the ways of ones' practical applications. A comprehensive study of US influence on the electrophysical (temperature, magnetofield, amplitude) characteristics of the specially selected samples with various composition and state of structural defects has been carried out with the help of advanced techniques of acoustodynamical methods (dynamic acousto-Hall, thermoacoustic annealing, pulse acoustoconductivity). It is shown the main US changes of MnHgTe and CdMnHgTe parameters are associated with mercury atoms redistribution between the bulk and dislocations. US influence on the electrophysical characteristics of dislocation-free p-Ge samples is revealed for the first time; it is also suggested the mechanism based on the acousto-induced inversion population of light and heavy holes levels and increasing of charge carriers scattering on the ionized impurities. It is revealed the opportunity of radiation defects modification and metastable centers state controlling by the means of ultrasound for gamma-irradiated n-Si crystals with different oxygen content; the energy levels of defects and their concentration are determined; diffusion and deformation mechanisms of US modification of radiation complexes are proposed. The reversible change of the conductivity by ultrasonic pulse loading is found for the first time; the possibility of acoustic spectroscopy of multicharged centers is shown.