Electron Tomography of Au-Catalyzed Semiconductor Nanowires

Electron tomography based on Z-contrast scanning transmission electron microscopy (STEM) can be applied to study 3D morphology of nanomaterials at high resolution, that is, 1 nm in all three spatial dimensions, to provide comprehensive insights into the structure of nanomaterials and their interfaces. Here, we report the 3D characterization of Au-catalyzed Ge and Si nanowires using a full-space tilting holder to address the “missing wedge” problem in STEM electron tomography. Electron tomography specimens were prepared by a novel two-step sample preparation process to minimize surface damage induced by focused ion beam (FIB) milling. The quality of specimen preparation protocol is demonstrated by the clear visibility of {112} facets in the reconstructed volume, and 3D morphology of Au nanoparticles on the nanowire surface. The 3D distribution of the Au nanoparticles on the coated Ge nanowires is also established. The integrated combination of innovative specimen preparation and full-tilt tomography represents a useful advance in the 3D analysis of nanostructures.