| Abstract Scope |
The advent of aberration correctors, pixelated direct electron detectors and monochromators marks major milestones in the development of transmission electron microscopy (TEM). The local structure, properties and dynamic behavior of materials can be studied by electron microscopy and spectroscopy. In this talk, a novel 4D STEM diffraction imaging technique is developed to map the local electric field and charge density in real space with sub-Å spatial resolution. With the 4D STEM methods, one can measure the electrical charge density, dipole moment, valence electron distribution in nanostructures and single defects. Furthermore, using the recently developed space- and angle-resolved vibrational electron energy-loss spectroscopy (EELS), we demonstrate a mapping of phonons revealing an interface mode at the Si-Ge interface and phonon dynamics of SiGe quantum dots (QDs). By utilizing averaged and resolved momentum conditions, phonon momenta can be imaged to obtain information about phonon propagation at the nanometer scale. |