Impurity level evolution and majority carrier-type inversion of Ag2S under extreme compression: Experimental and theoretical approaches

The ability to probe charge carriers transport behavior under pressure has the potential to unlock many key questions in photoconduction, resistive switch, solid ion transport, etc. We utilize the Hall-effect measurements and the first-principles calculations on Ag2S to reveal the pressure induced changes in its electrical transport parameters. Beyond 7.8 GPa, the donor level in modified monoclinic phase moves away from the conduction-band minimum as the pressure increases, and then Ag2S changes its dominant majority carriers from electrons to holes around 13.5 GPa. Additionally, increasing the pressure makes the electrical resistivity of Ag2S trend to decrease with temperature. At 15.8 GPa, Ag2S undergoes a transformation from metallic-like conduction to semiconductor conduction. These results are beneficial to achieve unique properties of high-pressure phases and develop Ag2S applications under ambient or extreme conditions.