Electronic structure analysis of Mn- and Fe-codoped In ₂O ₃ by photoemission yield measurements

The valence band electronic structures of Mn- and/or Fe-doped In ₂O ₃, i.e., In ₂O ₃:Mn, In ₂O ₃:Fe, and In ₂O ₃:(Mn, Fe), are investigated by photoemission yield measurements. Significant changes are observed in the threshold energy of photoemission, depending on the doped magnetic ions, which indicates that an additional occupied band appears above the top of the valence band of In ₂O ₃ owing to doping with Mn and/or Fe ions. It is confirmed that the order of the threshold energies of photoemission, E _PET, is E _PET(In ₂O ₃:Mn)<E _PET(In ₂O ₃:(Mn, Fe))<E _PET(In ₂O ₃:Fe)<E _PET(In ₂O ₃). To gain a better understanding of these results, first-principles molecular orbital calculations are also carried out, which successfully explain the observed changes in the photoemission threshold energies.