Fermi level shift in La1−xSrxMO3 (M=Mn, Fe, Co, and Ni) probed by Schottky-like heteroepitaxial junctions with SrTi0.99Nb0.01O3

Abstract

The authors have studied electrical properties of perovskite heteroepitaxial junctions consisting of transition metal oxides ${\mathrm{La}}_{1-x}{\mathrm{Sr}}_{x}M{\mathrm{O}}_3$ ($\mathrm{LS}M\mathrm{O}$ : $M=\mathrm{Mn}$ , Fe, Co, and Ni) and an $n$ -type semiconductor $\mathrm{Sr}{\mathrm{Ti}}_{0.99}{\mathrm{Nb}}_{0.01}{\mathrm{O}}_3$ (Nb:STO). The junctions showed rectifying current-voltage characteristics that could be analyzed by taking into account a Schottky-like barrier formed in the Nb:STO at the interfaces. As the doping level $x$ is increased, the Schottky barrier height and built-in potential increase as $\sim x$ (eV), indicating the downward shift of the Fermi level position in the $\mathrm{LS}M\mathrm{O}$ . The Fermi level position in the $\mathrm{LS}M\mathrm{O}$ with the same doping level $x$ tends to be deepened with increasing the atomic number of $M$ , in the order of Mn, Fe, Co, and Ni.