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

The hole-doped (p-) manganite La0.7Ca0.3MnO3 and the electron-doped (n-) ma nganite La0.7Ce0.3MnO3 undergo an insulator-to-metal transition at around 2 50 K, above which both behave as a polaronic semiconductor. We have fabrica ted an epitaxial trilayer (La0.7Ca0.3MnO3/SrTiO3/La0.7Ce0.3MnO3), where SrT iO3 is an insulator. At room temperature, i.e., in the semiconducting regim e, it exhibits asymmetric current-voltage (I-V) characteristics akin to a p -n diode. The observed asymmetry in the I-V characteristics disappears at l ow temperatures where both the manganite layers are metallic. These results indicate that using the polaronic semiconducting regime of doped manganite s, a p-n diode can be constructed. (C) 2001 American Institute of Physics.