Abstract

Understanding the atomic-scale structures of surfaces and interfaces is essential to control the functional properties of many materials and devices. Recent advances in aberration-corrected scanning transmission electron microscopy (STEM) have made possible the direct characterization of localized atomic structures in materials, especially at interfaces. In STEM , a finely focused electron probe is scanned across the specimen and the transmitted and/or scattered electrons from a localized volume of the material are detected by the post-specimen detector(s) as a function of raster position. By controlling the detector geometry, we gain flexibility in determining the contrast characteristics of the STEM images and the formation mechanisms involved. Thus, it may be possible to obtain further useful information by exploring new detector geometries in atomic-resolution STEM .  Recently, we have developed segmented type STEM detector capable of atomic-resolution imaging and proposed new imaging possibilities by controlling detector geometries: annular bright-field (ABF) imaging and atomic-resolution differential phase contrast (DPC) imaging ABF -STEM imaging enables us to directly image light element atomic columns of materials. DPC -STEM imaging can be used to detect local electric fields even at atomic dimensions. In this talk, we will review our recent researches on the development of atomic-resolution STEM imaging techniques and some STEM applications to material interface characterization.