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.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,HOU Zhi-qing,ZHAO Bin,WANG Yun-ming,WEI Dong-rui,DONG Lei,ZENG Hao-yu,SONG Jian-min.#$NP Structure and Ferroelectric Photovoltaic Properties of Epitaxial BiFeO3 Thin Films on MgO Substrate[J].Surface Technology,2023,52(6):377-383 |
| MgO基外延BiFeO3薄膜的结构和铁电光伏性能 |
| #$NP Structure and Ferroelectric Photovoltaic Properties of Epitaxial BiFeO3 Thin Films on MgO Substrate |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.06.034 |
| 中文关键词: 外延薄膜 BiFeO3 磁控溅射 铁电光伏 |
| 英文关键词:epitaxial films BiFeO3 magnetron sputtering ferroelectric photovoltaic |
| 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) |
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| Author | Institution |
| HUO Xing-min | School of Science, Hebei Agricultural University, Hebei Baoding 071001, China |
| ZHANG Xian-gui | School of Science, Hebei Agricultural University, Hebei Baoding 071001, China |
| LIU Li-fang | School of Science, Hebei Agricultural University, Hebei Baoding 071001, China |
| HOU Zhi-qing | School of Science, Hebei Agricultural University, Hebei Baoding 071001, China |
| ZHAO Bin | School of Science, Hebei Agricultural University, Hebei Baoding 071001, China |
| WANG Yun-ming | School of Science, Hebei Agricultural University, Hebei Baoding 071001, China |
| WEI Dong-rui | School of Science, Hebei Agricultural University, Hebei Baoding 071001, China |
| DONG Lei | School of Science, Hebei Agricultural University, Hebei Baoding 071001, China |
| ZENG Hao-yu | School of Science, Hebei Agricultural University, Hebei Baoding 071001, China |
| SONG Jian-min | School of Science, Hebei Agricultural University, Hebei Baoding 071001, China |
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| 中文摘要: |
| 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 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 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 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。 |
| 英文摘要: |
| Bismuth ferrite BiFeO3 (BFO), a multiferroic material with both ferroelectric and antiferromagnetic properties, has great potential in ferroelectric photovoltaic applications due to its large residual polarization (~100 μC/cm2), high Curie temperature (~810 ℃) and suitable band gap (~ 2.7 eV). In particular, the thin film structure has more excellent 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 heterostructure 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 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 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 relaxation 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, respectively. 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 photovoltaic mechanism in BFO ferroelectric film. It was found that a large work function difference (~1 eV) between the bottom electrode LSCO and the top electrode Pt film resulted in a strong built-in electric field in the BFO film, which was beneficial to the separation of photo-generated carriers, thereby greatly improving the BFO ferroelectric photovoltaic effect of thin films. In all, this study not only shows that BFO is an excellent and environmentally friendly photovoltaic candidate material with great potential application value, and also provides a practical strategy for improving the performance of BFO ferroelectric photovoltaic devices. |
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