During the 1990's, 20-200meV level electronic structure was obtained from nanometer-sized particles, single defects, and Si and Si-Ge quantum wells, using Spatially Resolved Electron Energy Loss Spectroscopy in the electron microscope. It became apparent during this work, however, that the available 2 Angstrom spatial resolution was not adequate to address the growing need for atomic level characterization of semiconductor devices for local composition, structure and electronic behavior. Thus, correction of aberrations within the electron microscope, an unattained dream for the first 50 years of electron microscopy, became a necessary capability for development of present and future semiconductor products. Aberration correction produces not only a true sub-Angstrom resolution for the first time, but it reveals a dynamic landscape of individual atoms on surfaces and within the bulk. As it becomes easier to precisely control the microscope electron optical system, it will soon be possible to extend the spectroscopy to 10-30 meV energies, making accessible phonons, structural transitions, bandgaps in nanotubes, carrier plasmons, low frequency dielectric constants and possibly carrier transport channels in single molecules -- all with sub-Angstrom spatial resolution. These excitations will likely exhibit unforeseen behavior, resulting from the physical confinement in nanometer-sized systems.
Host: Leonard Feldman