PRESSURE-INDUCED METALLIZATION AND SUPERCONDUCTIVITY IN InP AND InN

The electronic band structure, structural phase transition, metallization and superconducting transition of cubic zinc blende-type indium phosphide (InP) and indium nitride (InN), under pressure, are studied using TB-LMTO method. These indium compounds become metals and superconductors under high pressure but before that they undergo structural phase transition from ZnS to NaCl structure. The ground-state properties and band gap values are compared with the experimental and previous theoretical results. From our analysis, it is found that the metallization pressure increases with increase of lattice constant. The superconducting transition temperatures (T-c) of InP and InN are obtained as a function of pressure for both the ZnS and NaCl structures and these compounds are identified as pressure-induced superconductors. When pressure is increased T-c increases in both the normal (ZnS) and high pressure (NaCl) structures. The dependence of T-c on electron-phonon mass enhancement factor lambda shows that InP and InN are electron-phonon mediated superconductors. The non-occurrence of metallization, phase transition and onset of superconductivity simultaneously in InP and InN are confirmed.