沉积温度对BiFeO3薄膜的微观结构与化学计量比的影响

沉积温度对BiFeO₃薄膜的微观结构与化学计量比的影响

雷炜斌，齐瑞娟^*，张怀斌

（物理与电子科学学院，华东师范大学，上海200241）

摘  要    采用高分辨透射电子显微镜并结合选区电子衍射、X射线能谱仪技术研究沉积温度对BiFeO₃薄膜的微观结构与化学计量比的影响。与600℃和700℃沉积的BiFeO₃薄膜相比，在500℃沉积的BiFeO₃薄膜表面出现了许多岛状的二次相，即Bi₂O₃。当沉积温度提高到600℃和700℃时，外延BiFeO₃薄膜是单晶，并且与SrRuO₃缓冲层匹配良好，而且没有出现位错和二次相。通过大量的EDS数据统计分析，在500℃、600℃和700℃生长的BiFeO₃薄膜，它们的Bi/Fe摩尔比分别为0.798、0.906和0.870，其中，Bi元素的缺乏可能是由于500℃时析出物Bi₂O₃的形成和700℃时Bi的挥发所致。

关键词    微观结构；化学计量；温度

中图分类号：TG115.21⁺5.3   文献标识码：A     doi:10.3969/j.issn.1000-6281.2021.01.002

Effect of deposition temperature on microstructure and stoichiometric ratio of BiFeO₃ thin films

LEI Wei-bin，QI Rui-juan^*，ZHANG Huai-bin

(School of Physics and Electronic Sciences, East China Normal University, Shanghai 200241，China)

Abstract The relationship of the microstructure and stoichiometry of BiFeO₃ (BFO) thin films with variable substrate temperatures was investigated by high resolution transmission electron microscope (HRTEM) combining with selected area electron diffraction (SAED) and X-ray energy dispersive spectrometer (EDS) techniques. Comparing with the flat surface of BFO films deposited at 600℃and 700℃, many island-shaped secondary phases appear at the surface of BFO film deposited at 500°C, which are identified as Bi₂O₃. When the deposition temperature is increased to 600℃and 700℃, the epitaxial BFO films are perfect single crystals matching well with SRO electrode layers without dislocation and secondary phases. Through statistical analysis of a large number of EDS data, the Bi/Fe molar ratios are 0.798, 0.906 and 0.870 for BFO films grown at 500℃，600 ℃and 700℃, respectively. The deficiencies of Bi element are probably caused by the formation of Bi₂O₃ precipitates at 500℃and the evaporation of Bi at 700℃.

keywords  microstructure；stoichiometry；temperature

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