Fabrication and I-V characteristics of p-n junctions composed of high-Tc superconductors and La-doped SrTiO3

We have fabricated heterojunction structures comprising p-type high-Tc superconductor (YBCO) and n-type La-doped SrTiO3 (La-STO). (001) and (110) oriented-YBCO thin films were prepared on the (001) and (110)-oriented La-STO substrates, respectively, with the pulsed laser deposition technique. X-ray diffraction measurements confirm that the (001) and (110) YBCO thin films are epitaxially grown on the substrates. The fabricated junctions with both orientations show rectifying I-V characteristic, but their behavior are rather different depending on the orientation. The threshold voltages in the forward bias region increase with decreasing temperature.