1、第 52 卷 第 6 期 表面技术 2023 年 6 月 SURFACE TECHNOLOGY 377 收稿日期：20220327；修订日期：20220831 Received：2022-03-27；Revised：2022-08-31 基金项目：河北农业大学自主培养博士科研启动经费（PY201809，PY2021005，PY2021012）；河北农业大学师生协同项目（2021-BHXT-20）；河北农业大学创新创业训练计划项目（S202110086039，2020259，2022164）Fund：Starting Fund for Independent Doctoral Research
2、of Hebei Agricultural University(PY201809,PY2021005,PY2021012);Collaborative Project Between Teachers and Students of Hebei Agricultural University(2021-BHXT-20);Innovation and Entrepreneurship Training Program of Hebei Agricultural University(S202110086039,2020259,2022164)作者简介：霍幸民（2000），男，主要研究方向为功能
3、薄膜材料与器件。Biography：HUO Xing-min(2000-),Male,Research focus:functional thin film materials and devices 通讯作者：曾浩宇（1978），男，硕士，实验师，主要研究方向功能薄膜材料与器件。Corresponding author：ZENG Hao-yu(1978-),Male,Master,Research associate,Research focus:functional thin film materials and devices.通讯作者：宋建民（1976），男，博士，副教授，主要研究方向
4、功能薄膜材料与器件。Corresponding author：SONG Jian-min(1976-),Male,Doctor,Associate professor,Research focus:functional thin film materials and devices.引文格式：霍幸民,张宪贵,刘立芳,等.MgO 基外延 BiFeO3薄膜的结构和铁电光伏性能J.表面技术,2023,52(6):377-383.HUO Xing-min,ZHANG Xian-gui,LIU Li-fang,et al.Structure and Ferroelectric Photovoltaic
5、Properties of Epitaxial BiFeO3 Thin Films on MgO SubstrateJ.Surface Technology,2023,52(6):377-383.MgO 基外延 BiFeO3薄膜的结构和铁电光伏性能 霍幸民，张宪贵，刘立芳，侯志青，赵彬，王云明，魏东蕊，董磊，曾浩宇，宋建民（河北农业大学 理学院，河北 保定 071001）摘要：目的目的 深入研究 BiFeO3(BFO)薄膜的结晶结构、生长取向及测试温度对其介电和铁电光伏性能的影响。方法方法 采用偏轴磁控溅射法，分别以单晶(001)MgO 基片和外延 La0.5Sr0.5CoO3（LSCO）薄膜
6、作为衬底与底电极，构架 Pt/BFO/LSCO/MgO 异质结构的铁电电容器。采用 XRD 衍射仪表征 LSCO 和 BFO 薄膜的结构与生长取向，探究 Pt/BFO/LSCO/MgO 异质结构电容器的介电和铁电光伏性能，重点研究测试温度对其性能的综合影响。结果结果 X 射线衍射（XRD）和 Phi 扫描结果表明，MgO 基 BFO 与 LSCO 薄膜均为结晶良好的钙钛矿结构，且满足(00l)取向的外延生长。不同电压和频率下的介电测试表明，BFO 铁电薄膜具有较强的铁电性，正负矫顽电压分别为 3.36、1.12 V，但存在明显的介电色散现象，呈现先减小、后增大的趋势。在100 kHz时，介电损
7、耗最小，为 0.016；在 8 MHz 时，增加到了 0.212。这主要由于不同频率下各种类型电荷的弛豫竞争机制所致。光伏性能测试表明，在室温（20）、光强 250 mW/cm2紫光垂直照射下，开路电压（VOC）和短路电流（JSC）分别为 0.32 V 和 0.21 mA/cm2。进一步提高测试温度（分别为 40、60、80、100）发现，BFO 铁电薄膜 VOC呈先缓慢、后快速减小，而 JSC呈先快速上升、后下降的趋势，并在临界温度 80 处展现了更快的光伏响应速度，VOC和 JSC分别为 0.30 V 和 0.96 mA/cm2。能带分析表明，底电极 LSCO 与上电极 Pt 间大的功函数
8、差（1 eV）使得 BFO 薄膜中存在较强的内建电场，这有利于分离光生载流子，从而极大提高了BFO 薄膜的铁电光伏效应。结论结论 BFO 是一种具有重要潜在应用价值的优良环保光伏候选材料，提供了一种提高BFO 铁电光伏器件性能的切实可行策略。关键词：外延薄膜；BiFeO3；磁控溅射；铁电光伏 中图分类号：O484 文献标识码：A 文章编号：1001-3660(2023)06-0377-07 DOI：10.16490/ki.issn.1001-3660.2023.06.034 378 表 面 技 术 2023 年 6 月 Structure and Ferroelectric Photovolt
9、aic Properties of Epitaxial BiFeO3 Thin Films on MgO Substrate HUO Xing-min,ZHANG Xian-gui,LIU Li-fang,HOU Zhi-qing,ZHAO Bin,WANG Yun-ming,WEI Dong-rui,DONG Lei,ZENG Hao-yu,SONG Jian-min(School of Science,Hebei Agricultural University,Hebei Baoding 071001,China)ABSTRACT:Bismuth ferrite BiFeO3(BFO),a
10、 multiferroic material with both ferroelectric and antiferromagnetic properties,has great potential in ferroelectric photovoltaic applications due to its large residual polarization(100 C/cm2),high Curie temperature(810)and suitable band gap(2.7 eV).In particular,the thin film structure has more exc
11、ellent photoelectric conversion efficiency than single crystal and ceramics.In order to deeply investigate crystalline structure,growth orientation,and effect of test temperature on the dielectric and ferroelectric photovoltaic properties of BFO thin films,the Pt/BFO/La0.5Sr0.5CoO3(LSCO)/MgO heteros
12、tructure ferroelectric capacitor was fabricated by employing off-axis magnetron sputtering,in which the single crystal(001)MgO and epitaxial LSCO film were used as substrates and bottom electrodes,respectively.Some important results were obtained as follows.Firstly,the X-ray diffraction(XRD)and Phi
13、scanning results indicated that the MgO based BFO and LSCO films were not only both good crystallized perovskite structure,but also(00l)epitaxial relationships with MgO substrate.Secondly,when tested at different voltages and frequencies,the BFO ferroelectric film exhibited a stronger ferroelectric
14、property,in which the positive and negative coercive voltages were about 3.36 V and 1.12 V,respectively.However,a obvious dielectric dispersion phenomenon was also observed,namely,dielectric loss had a minimum value of 0.016 at 100 kHz and increased to 0.212 at 8 MHz,which was mainly due to the rela
15、xation competition mechanism of various types of charges in BFO ferroelectric film.Thirdly,under a vertical 250 mW/cm2 purple light at room temperature(20),the photovoltaic performances revealed that the open circuit voltage(VOC)and short circuit current(JSC)were about 0.32 V and 0.21 mA/cm2,respect
16、ively.By further increasing test temperatures from 40 C to 100 C with an interval of 20 (40,60,80 and 100),it was found that the values of VOC decreased slowly and then rapidly,while the amplitudes of JSC increased rapidly and then decreased.At a critical temperature of 80,the BFO ferroelectric film exhibited a faster photovoltaic response speed,in which the values of VOC and JSC were about 0.30 V and 0.96 mA/cm2,respectively.Finally,the energy band analysis was also conducted to study photovolt
