MSE Seminar: Understanding nanoscale transport at interfaces and defects using in situ TEM
Speaker: Dr. Matthew Mecklenburg, Senior Staff Scientist, University of Southern California, Core Center of Excellence in Nano Imaging (CNI)
Title: Understanding nanoscale transport at interfaces and defects using in situ transmission electron microscopy
Transmission electron microscopy (TEM) is a powerful tool for studying interfaces and defects down to the atomic scale. Image contrast in a TEM is dominated by changes in crystal orientation, atomic number, and mass thickness. But new contrast mechanisms can be found by precision measurements of plasmon excitations, the lattice parameter, and charge compensating currents. New imaging techniques with nanoscale spatial resolution can detect contrast changes that relate to temperature, electrical potential, and pressure. These scalar fields have gradients that produce thermal, electrical, and mass transport. Thus, applying these new techniques to map these scalar fields allows us correlate transport to interfaces and defects in nanostructured materials. One goal is to use precision measurements to map temperature in transistors and help understand how to mitigate the enormous heat produced from electronics on the scale of server farms down to cellular phones. The ubiquitous transistor produces temperature gradients of kelvins per nanometer. The interface around the sub-10 nm wide gate and semiconductor components prevents diffusive transport in favor of ballistic transport, requiring high spatial resolution measurements of temperature change to observe this crossover.