Pressure-engineered optical properties and emergent superconductivity in chalcopyrite semiconductor ZnSiP2

Chalcopyrite II-IV-V2 semiconductors are promising materials in nonlinear optical, optoelectronic, and photovoltaic applications. In this work, pressure-tailored optical properties as well as pressure-driven emergent superconductivity in chalcopyrite ZnSiP2 are reported via photoluminescence (PL) spectroscopy and electrical transport experiments. During compression, the PL peak energy exhibits a plateau between 1.4 and 8.7 GPa, which is accompanied by a piezochromic transition and correlated with the progressive development of cation disorder. Upon further compression across a phase transition from tetragonal to cubic rock-salt structure, superconductivity with a critical temperature Tc ~ 8.2 K emerges immediately. Tc decreases in the range of 24.6–37.1 GPa but inversely increases at higher pressures, thereby exhibiting an unusual V-shaped superconducting phase diagram. These findings present vivid structure–property relationships, which not only offer important clues to optimize the optical and electronic properties, but also provide a new way to use compression to switch between different functionalities. A semiconductor that is compatible with silicon but has better optical properties has been fully characterized by researchers in China. Silicon is perhaps the best-known example of a semiconductor but is not good at emitting light. Scientists continue to identify and characterize alternatives that might be better suited for specific applications. Yifang Yuan from the High Magnetic Field Laboratory in Hefei and co-workers have investigated in detail the properties of semiconducting zinc-silicon-phosphorus. ZnSiP2 is a member of a class of materials known as chalcopyrites and is compatible with and can be grown on silicon but is better at generating light. The team studied how external pressure affects the semiconductor’s structural, optical and electronic properties. They showed that at a sufficiently high pressure, the semiconductor exhibits superconducting behavior. Pressure engineered optical properties as well as presssure induced emergent superconductivity are revealed in II-IV-V2 semiconductor ZnSiP2, which demonstrate vivid structure–property relationships. Especially, along with a structural phase transition from tetragonal to cubic phase under compression, ZnSiP2 evolves from a photovoltaic semiconductor into a superconductor.