The Techniques of Thermoelectric, Galvanomagnetic and Thermomagnetic Measurements at Ultrahigh Pressure

摘要

In present paper the combine technique for materials testing at ultrahigh pressure and the setups are described. The novel technique of thermomagnetic measurements of semiconductor micro-samples under high pressure up to 30 GPa tested at lead chalcogenides (n-PbTe, p-PbSe, p-PbS) is discussed. Using this technique a values of mobilities of charge carriers, and a scattering parameters have been estimated both for initial NaCl-phases and also for high pressure GeS-phases. The new results obtained are: observation of gapless state with the high values of electron mobilities at room temperatures for PbTe and PbSe, reversible inversion of scattering parameter of charge carriers under pressure for PbSe near the phase transition point, establishment of indirect minimal semiconductor energy gap at high pressure GeS-phase of PbTe and PbSe. Thermomagnetic effects were shown to be more sensitive in compare with traditional galvanomagnetic ones. Both the effects observed and the technique developed may find a technical application, for example, in MEMS (micro-electro-mechanical systems) technologies.