2010.12.09

Auditorium, 1st floor, Engineering Bld #9, Hongo Campus

Prof. Klaus van Benthem
       University of California, Davis

Title：Imaging Nanofunctionality: field assisted sintering and dielectric breakdown in the TEM

Abstract：
Transmission Electron Microscopy has enabled the direct imaging of microstructural details of materials. The recent advent of aberration correction for Scanning Transmission Electron Microscopy (STEM) provides tools for the structural and chemical characterization of defect structures with sub-Ångström spatial resolution and single atom sensitivity. Novel in situ STEM techniques available in our laboratory will be discussed during the presentation that offer capabilities to characterize the evolution of atomic-scale defect structures under applied stress, such as heat and heating rates, electrical fields and currents.

We have applied electrical stress to ultrathin dielectric films to investigate atomic scale dielectric breakdown mechanisms that are relevant for the performance of field effect transistors. First results indicate the formation of areas in which dielectric breakdown induced epitaxy forms a conductive pathway across the dielectric thin film.

The application of electrical fields combined with heating rates of several hundred centigrade per minute was shown to be an effective pathway for the rapid consolidation of nanometric powder particles to obtain microstructures achieving 100% of their theoretical density. Such microstructures demonstrate exciting new properties due to grain sizes that often remain below 100nm. During my presentation I will discuss how we are currently applying in situ TEM/STEM techniques to identify the fundamental atomic scale mechanisms that lead to rapid densification while grain growth is suppressed.

Schedule：16:00-17:30 Thursday, December 9th, 2010

Place：Auditorium, 1st floor, Engineering Bld #9, Hongo Campus

Attached file： The 72nd Open Seminar.pdf