Plan-view TEM of planar interfaces
Transmission electron microscopy (TEM), incorporating imaging, diffraction and spectrometry has contributed significantly to the understanding of the structure of crystalline interfaces. Traditionally, planar interfaces are investigated using cross-sectional views (electron beam parallel to the interface) of the specimen. However, plan-view TEM (PVTEM) has recently emerged as a viable and supplementary technique to cross-sectional TEM (XTEM). PVTEM enjoys certain definite advantages over XTEM. One important consideration is that the interface in a PV specimen is buried (sandwiched between two crystals) and is expected to be free of artefacts induced by specimen preparation procedures. Moreover, many multilayer electronic materials are amenable to PVTEM because they can be easily backthinned to electron transparency with virtually no damage to the internal interfaces. PV specimens clearly contain much larger interface area than XTEM specimens, which may be of great significance when statistics are considered. Apart from these considerations PVTEM studies can also offer specific information about the interface not always possible in XTEM. In this brief communication we report some of our results on imaging, diffraction and spectrometry of interfaces obtained by viewing the interfaces in the PV mode.