取向对铁酸铋薄膜漏电机制和光伏性能的影响

Effect of Orientation on Leakage Mechanism and Photovoltaic Properties in Bismuth Ferrite Thin Films

本文通过偏轴磁控溅射法,以不同取向钛酸锶SrTiO3 (STO)单晶基片为衬底,镧锶钴氧La0.5Sr0.5CoO3 (LSCO)为底电极,铁酸铋BiFeO3 (BFO)为铁电介质,构架了Pt/BFO/LSCO/STO异质结电容器。XRD结果显示不同取向的BFO薄膜均为外延结构。研究了不同取向Pt/BFO/LSCO异质结的漏电机制和光伏性能。J-V数据拟合表明,Pt/BFO/LSCO漏电流大小依赖于BFO薄膜取向,满足(001)J 】(110)J 】(111)J规律。不同取向Pt/BFO/LSCO异质结的导电机制均为:低电场欧姆导电和高电场肖特基导电。通过铁电光伏系统对Pt/BFO/LSCO异质结的光伏性能进行了测量,结果表明开路电压VOC和短路电流JSC强烈依赖于BFO薄膜取向,(111)取向最大、(110)取向次之、(001)取向最小。

The Pt/BFO/LSCO/STOheterojunction capacitor were fabricated on three oriented SrTiO3 (STO)single crystal substrates by off-axis RF magnetron sputtering, La0.5Sr0.5CoO3 (LSCO) as bottle electrode and BiFeO3 (BFO) film as ferroelectricmedium. XRD results show that BFO films with different orientations areepitaxial. The leakage mechanism and photovoltaic performance of Pt/BFO/LSCOheterostructure are studied. The fitting of J-V data shows that the leakagecurrent of Pt/BFO/LSCO depends on the orientation of BFO films, which satisfiesthe rule of (001)J >(110)J >(111)J. The conduction mechanisms ofPt/BFO/LSCO heterostructure with different orientations are: low electric fieldohmic conduction and high electric field Schottky conduction. The photovoltaiccharacteristics of Pt/BFO/LSCO heterostructureare characterized byferroelectric photovoltaic system. The results show that the Voc andJsc strongly depend on the orientation of BFO film, with (111)orientation the largest, (110) the second and (001) the smallest.