The bandgap of SrBi2Ta2O9
The bandgap of SrBi2Ta2O9
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DOI：
10.1080/10584589708221690
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发表时间：
1997-09
影响因子：
0.7
通讯作者：
A. Hartmann;R. Lamb;J. Scott;C. Gutleben
中科院分区：
文献类型：
--
作者：
A. Hartmann;R. Lamb;J. Scott;C. Gutleben
摘要研究了铁电随机存储器所用的SrBi2Ta2O9薄膜的电子结构。用表面灵敏X射线光电子能谱(XPS)分析了价带，用近边X射线吸收谱(NEXAS)研究了与导带相关的空态的部分密度。NEXAFS谱的形状与前面给出的计算结果大致一致，但金属态(特别是铋)似乎更宽。NEXAFS测量是在两个不同的信息深度(∼100A和∼2000A)下进行的，这表明块体和近表面区域之间没有明显的电子结构差异。用体敏紫外可见吸收光谱和表面敏感电子能量损失谱测量了带隙。数据表明，该薄膜材料的禁带宽度约为4 eV，低于建议的p。
Abstract The electronic structure of SrBi2Ta2O9 thin films, which are of interest for ferroelectric random access memories, has been investigated. The valence band has been analysed using surface sensitive X-ray photoemission spectroscopy (XPS), while the partial density of unoccupied electronic states associated with the conduction band has been investigated using near edge X-ray absorption spectroscopy (NEXAS). The shapes of the NEXAFS spectra are roughly in agreement with calculations presented previously, however, the metal states (especially bismuth) appear to be broader. The NEXAFS measurements were performed for two different information depths (∼100A and ∼2000A) which indicated no significant electronic structural differences between the bulk and the near-surface region. The bandgap has been measured using bulk sensitive UV-visible absorption and surface sensitive electron energy loss spectroscopy. The data indicated that the bandgap of the thin film material is ca. 4 eV and lower than suggested p...