Liakh-Kahuy N. Electro- and magnetotransport properties in the basic sensory Si, Ge, InSb, GaSb whiskers in the vicinity to the metal-insulator transition

The thesis is devoted to the complex studies of electro- and magnetotransport properties of the basic sensory semiconductor whiskers in the wide ranges of temperature and magnetic field were carried out. New effects were observed in whiskers, in particular, the first appearance of the Berry phase on the magnetoresistance field dependences at the liquid helium temperature in strained n-type conductivity InSb and GaSb whiskers due to the strong spin-orbit interaction of charge carriers in the vicinity to the metal-insulator transition that confirms the two-dimensional nature of the electron gas in crystals. A transition from the effect of weak antilocalisation to the weak localization of charge carriers at temperature about 4 K was detected in heavy doped whiskers with a metallic type of conductivity in weak magnetic fields due to a change in the temperature correlation between dephasing time and electron spin relaxation time. Surface superconductivity was first observed at a critical temperature of 4.2 K in GaSb whiskers doped with tellurium due to the strong spin-orbit exchange interaction of charge carriers in the metal phase in the vicinity to the metal-insulator transition. The influence of external factors (strain, magnetic field, electron irradiation, temperature) on the properties of doped Si, Ge, InSb and GaSb whiskers as sensitive elements of mechanical, thermal and magnetic sensors was studied. The physical representations about the transport mechanisms of charge carriers are expanded due to the conducted studies for doped semiconductor microcrystals in the vicinity to the metal-insulator transition at low temperatures in strong magnetic fields and under the influence of high-energy electron irradiation. The concept of creating supersensitive radiation-sensitive piezoresistance sensors has been developed due to the discovered new kinetic effects in the whiskers. These sensors, which can be used in various fields of science and technology, are capable of extreme operating conditions, in particular at cryogenic temperatures, in strong magnetic fields with irradiation by high-energy electrons.