Pressure-induced phase transitions in Si observed by thermoelectric power measurements

For the first time the phase transitions under high pressure P up to 20 GPa have been observed in Czochralski-grown Si single crystals by thermoelectric power S measurements. Values of S≈+8±3 μV/K have been determined for tetragonal, orthorhombic and simple hexagonal high-pressure phases. The behaviour of S(P) was found to be rather different for different Si samples—initial and pre-treated by high temperatures 450–650 °C under hydrostatic pressure 0–1.5 GPa.