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

Abstract
The hole-doped (p-) manganite La 0.7 Ca 0.3 MnO 3 and the electron-doped (n-) manganite La 0.7 Ce 0.3 MnO 3 undergo an insulator-to-metal transition at around 250 K, above which both behave as a polaronic semiconductor. We have fabricated an epitaxialtrilayer ( La 0.7 Ca 0.3 MnO 3 / SrTiO 3 / La 0.7 Ce 0.3 MnO 3 ) , where SrTiO 3 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.