Department of Materials Science and Engineering, University of Illinois, Urbana, IL 61801, USA; Seitz Materials Research Laboratory, University of Illinois, Urbana, IL 61801, USA.
Ultramicroscopy. 2014 Jan;136:50-60. doi: 10.1016/j.ultramic.2013.07.018. Epub 2013 Aug 7.
A real space approach is developed based on template matching for quantitative lattice analysis using atomic resolution Z-contrast images. The method, called TeMA, uses the template of an atomic column, or a group of atomic columns, to transform the image into a lattice of correlation peaks. This is helped by using a local intensity adjusted correlation and by the design of templates. Lattice analysis is performed on the correlation peaks. A reference lattice is used to correct for scan noise and scan distortions in the recorded images. Using these methods, we demonstrate that a precision of few picometers is achievable in lattice measurement using aberration corrected Z-contrast images. For application, we apply the methods to strain analysis of a molecular beam epitaxy (MBE) grown LaMnO₃ and SrMnO₃ superlattice. The results show alternating epitaxial strain inside the superlattice and its variations across interfaces at the spatial resolution of a single perovskite unit cell. Our methods are general, model free and provide high spatial resolution for lattice analysis.
基于模板匹配的实空间方法用于原子分辨率 Z 衬度成像的晶格定量分析。该方法称为 TeMA，使用原子列或原子列组的模板将图像转换为相关峰的晶格。通过使用局部强度调整相关和模板设计来帮助实现这一点。在相关峰上进行晶格分析。使用参考晶格校正记录图像中的扫描噪声和扫描变形。使用这些方法，我们证明了使用像差校正的 Z 衬度成像可以实现晶格测量的几皮米精度。在应用方面，我们将这些方法应用于分子束外延（MBE）生长的 LaMnO₃ 和 SrMnO₃ 超晶格的应变分析。结果表明，在超晶格内部和界面处的交替外延应变及其在单个钙钛矿单元晶格的空间分辨率上的变化。我们的方法是通用的、无模型的，并为晶格分析提供高空间分辨率。
