Determination of band diagram for a p-n junction between Mott insulator LaMnO3 and band insulator Nb:SrTiO3

The authors report on the band diagram of epitaxial p-n junctions between the Mott insulator with “p-type carriers” LaMnO3 and the n-type semiconductor Nb-doped SrTiO3 (Nb:STO) using x-ray photoemission spectroscopy. By changing the donor concentration in Nb:STO from 0.1 at. % to 1.0 at. %, the value of the built-in potential for the Nb:STO side (Vbn) is reduced from 0.55 ± 0.05 eV to 0.25 ± 0.05 eV. The modulation of Vbn is well described in the framework of the conventional p-n junction model. These results suggest that the characteristics of perovskite oxide p-n junctions can be predicted and designed using the transport properties of the constituent oxides, irrespective of their strongly correlated electronic nature.