An energy scheme for interpreting deep-level photoconductivity and other recent optical measurement for Fe-doped InP

Abstract

Presents the low-temperature deep-level photoconductivity spectra of a wide range of n-type and semi-insulating Fe-doped InP crystals. The results differ in important respects from some recently reported photoconductivity work and conclusively demonstrate that Fe2+ rather than Fe+ is the stable charge state in n-type material. The electron ionisation threshold energy from the Fe2+ state to the lowest conduction band at 0.65 eV is found in all the samples studied. Only the semi-insulating show a strong photoconductivity threshold at 1.15 eV. This feature is absent in n-type InP(Fe). The authors tentatively assign this structure to an Fe-related level (Fe3+) 1.15 eV below the conduction band-edge.