Surface Channeling in Aberration-corrected STEM of Nanostructures

Abstract

Sub-Ångström resolution imaging and atomic resolution spectroscopy in aberration-corrected STEM are becoming routinely available, providing information on crystal structure, defect structure, elemental composition, and electronic structure with a sensitivity of, or approaching, individual atoms. To quantitatively interpret image intensities, however, requires a better understanding of the origin of the collected signals. We report here observation of anomalous intensity enhancement in sub-Ångström resolution HAADF images of surfaces and interfaces of ZnO nanostructures. We propose that the significant increase of the collected HAADF signal of a row of atom columns close to the crystal surface originates from a surface-resonance channeling effect [1].