SCANNING TRANSMISSION ELECTRON MICROSCOPY: AN EXPERIMENTAL TOOL FOR ATOMIC SCALE INTERFACE SCIENCE

Abstract. Although internal interfaces have long been known to dominate the performance of many materials systems critical to modern technology, there has yet been little incontrovertible evidence pointing to the fundamental origin of the structure-property relationships. However, the recent development of direct imaging and analysis techniques in the scanning transmission electron microscope (STEM) has provided a new experimental pathway to obtain information on the local atomic structure, chemical composition and bonding at interfaces on the fundamental atomic scale. This is precisely the information that is required to unravel the complexities of interfaces and opens up a new paradigm for investigating the structure-property relationships at internal interfaces. In this paper we discuss the practical aspects of the experimental STEM techniques and demonstrate the resolution possible in current commercially available instrumentation. The application of these techniques to the study of internal interfaces is highlighted by a discussion of the analysis of homophase interfaces in SrTiO3, Bi2Sr2Ca2Cu3O10 and YBa2Cu3O7-δ and the heterophase interfaces between GaAs and Au, and between Si and molecular beam epitaxy (MBE) grown II-VI semiconductors