Pressure-induced superconductivity in high-pressure phases of Si

Abstract

The electrical behavior of Si was studied for pressures up to 43 GPa and temperatures down to 2 K using a sintered-diamond-compact anvil cryogenic clamp press. Two types of samples, amorphous thin-film Si and semiconductor-quality crystalline Si, were used. The superconducting transition temperatures $T_c$ for high-pressure phases of the amorphous Si are about 3 K higher than those of the cystalline Si. The $T_c$ decreases monotonically for pressures higher than 25 GPa. No upturn in $T_c$ around 25 GPa as predicted theoretically for the simple-hexagonal phase was observed.