Backward-Like Rectifying Behavior of La 1.85 Sr 0.15 CuO 4 /Nb:SrTiO 3 Heterojunctions

La 1.85 Sr 0.15 CuO 4+ δ (LSCO)/Nb:SrTiO 3 (NSTO) heterojunction, in which the LSCO film was excessively annealed in pure oxygen, was created by a combined technique including pulsed electron deposition, photolithography, and Ar-ion milling. Subsequent characterizations via measuring the current–voltage ( I – V ) relations revealed great sensitivity of the rectifying properties to the annealing, where a backward-like diode behavior was observed, which probably can be interpreted in connection with the band diagram of the heterojunction, and more insulating interface resulted from over-annealing effect on both LSCO and NSTO was presumably the primary cause. This study will provide an opportunity to understand more about the complicated physics underlying the rich properties in such heterojunctions.