Depth-Resolution Imaging of Three-Dimensional Nano Structures Using Aberration-Corrected TEM
Abstract: The features and capabilities of depth-resolution imaging by aberration-corrected transmission electron microscopy (TEM) are explained in terms of phase-contrast transfer functions and Fresnel propagation of electron wave fields. The depth-resolution imaging is useful for obtaining three-dimensional information of nano structures as shown in the successful examples; detection of the inclination angle of a carbon nanotube (CNT), visualization of the grade separation crossing of CNTs, and thickness determination of an amorphous carbon film supporting a gold nano particle. In addition, a new standard for the exact focal plane is discussed in order to treat a finite-thickness material as a phase object. Based on the discussion, the depth-selective imaging is explained referring to the successful examples, in which upper and lower side wall lattices of a single-wall CNT were separately observed and a medium-range-order structure embedded in Zr66.7Ni33.3 metallic glass was detected using aberration-corrected TEM.
Key words: Aberration-corrected TEM, depth resolution, exact focal plane, depth-selective imaging, three-dimensional nano structures