p–n diode with hole- and electron-doped lanthanum manganites

Abstract

The hole-doped (p-) manganite La0.7Ca0.3MnO3 and the electron-doped (n-) manganite La0.7Ce0.3MnO3 undergo an insulator-to-metal transition at around 250 K, above which both behave as a polaronic semiconductor. We have fabricated an epitaxial trilayer (La0.7Ca0.3MnO3/SrTiO3/La0.7Ce0.3MnO3), where SrTiO3 is an insulator. At room temperature, i.e., in the semiconducting regime, it exhibits asymmetric current–voltage (I–V) characteristics akin to a p–n diode. The observed asymmetry in the I–V characteristics disappears at low temperatures where both the manganite layers are metallic. These results indicate that using the polaronic semiconducting regime of doped manganites, a p–n diode can be constructed.