Pressure-induced metallization of ZnSe

Abstract

High-pressure studies of the resistivity R of the direct-gap insulator ZnSe were carried out using diamond-anvil cells. The pressure dependence R(P) at 300 K in the pressure range of 0--20 GPa revealed a drastic drop in the resistance at P=13.5 GPa and upon decompression recovery of the insulating state at 10.5 GPa. From the temperature dependence of the resistance at P>13.5 GPa it has been concluded that (i) narrow-gap semiconducting and metallic phases coexist in the range 13.5--15 GPa, and (ii) a pure metallic state, characterized by a positive temperature slope and small resistivity value, exists at P>17 GPa. The results are discussed in terms of previous optical data and band-structure calculations.