Electrical transport properties of heteroepitaxial p-n junctions made of La0.8 Sr0.2 Co O3 and Sr Ti0.99 Nb0.01 O3 were studied. Junctions display highly rectifying current-voltage characteristics over a wide temperature range (20-300 K). Two distinct transport mechanisms are identified: tunneling assisted by interface states at T<130 K and diffusion/recombination at higher temperatures. Capacitance-voltage characteristics are used to determine the junction built-in potential at different frequencies. A capacitance relaxation is found due to charge trapping at interface states. Interface states, which deeply affect transport, are discussed in connection to charge-transfer processes related to the polarity mismatch at the interface.
Bibliographical noteFunding Information:
The work at UCM was supported by MEC MAT 2005—06024 C02 and work at UMN was supported by NSF DMR.