INM - Leibniz-Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany.
Micron. 2012 Jan;43(1):49-56. doi: 10.1016/j.micron.2011.05.011. Epub 2011 Jun 7.
ZnO with additions of Fe₂O₃ or In₂O₃ shows characteristic inversion domain structures. ZnO domains are separated by two types of inversion domain boundaries (IDBs): basal b-IDBs parallel to (0001) planes, and complementary pairs of three possible variants of pyramidal p-IDBs parallel to {2115} lattice planes. The structure and composition of IDBs were investigated in a sophisticated aberration-corrected scanning transmission electron microscope (probe-corrected TEM/STEM). It is shown that Fe and In additions are essentially located in monolayers within the IDBs, and EELS electron spectroscopic imaging (ESI) as well as EDS spectroscopic imaging by X-rays (SIX) are capable of rapidly mapping the element distribution. With solid solubility of trivalent dopant species well below 1at.% within ZnO domains, the lateral spacings of b-IDBs are inversely proportional to the dopant concentration. Quantification of data acquired by ESI and SIX from well defined sample regions in STEM both confirm the assumption of one full monolayer of dopants per IDB. Atom columns of cations are well resolved in HAADF STEM imaging; experimental contrast intensities are approximately proportional to Z¹·⁶. Furthermore, annular bright-field (ABF)-STEM imaging is capable of resolving oxygen columns even in thick sample regions, thus providing highly localized information on atom positions and lattice distortions, and enables the construction of more reliable structure models of IDBs in doped ZnO.
添加了 Fe₂O₃ 或 In₂O₃ 的 ZnO 表现出特征的反演畴结构。ZnO 畴由两种类型的反演畴界 (IDB) 隔开：平行于 (0001) 面的基底 b-IDB，以及平行于 {2115} 晶格面的三个可能的金字塔形 p-IDB 互补对。使用先进的像差校正扫描透射电子显微镜（探针校正 TEM/STEM）研究了 IDB 的结构和组成。结果表明，Fe 和 In 的添加本质上位于 IDB 内的单层中，电子能量损失谱（EELS）电子光谱成像（ESI）以及 X 射线（SIX）的能谱成像都能够快速绘制元素分布。由于三价掺杂剂在 ZnO 畴内的固溶度远低于 1at.%，因此 b-IDB 的横向间距与掺杂浓度成反比。通过 ESI 和 SIX 从 STEM 中定义明确的样品区域获得的数据的定量，都证实了每个 IDB 有一个完整的单层掺杂剂的假设。阳离子的原子列在 HAADF STEM 成像中得到很好的分辨；实验对比度强度大致与 Z¹·⁶成正比。此外，环形明场 (ABF)-STEM 成像能够分辨出甚至在厚样品区域中的氧原子列，从而提供了原子位置和晶格畸变的高度局部化信息，并能够构建掺杂 ZnO 中 IDB 的更可靠结构模型。
