Abnormal rectifying behavior of In/SrTiO3/SrTiO3 :Nb capacitor

In/SrTiO3/SrTiO3:Nb capacitors have been fabricated by depositing SrTiO3 thin film on Nb-1 wt%-doped SrTiO3 substrate and using In as the top electrode. The current–voltage characteristics were measured and backward rectifying characteristics are found below room temperature. The interesting observation is that at constant negative bias the leakage current increases with decreasing temperature below 150 K. Analysis shows that the abnormal increasing current was determined by the tunneling process through the SrTiO3/SrTiO3:Nb junction. This work demonstrates that tunneling diode may be realized in homologous perovskite oxides and engineered by distortions and defects.