Plenary Lecture

David A. Muller
Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, USA

Electron energy loss spectroscopy (EELS) in a new generation of aberration-corrected electron microscopes provides direct images of the local physical and electronic structure inside a material at the atomic scale. The sensitivity and resolution can extend to imaging single dopant atoms or vacancies in their native environments Comparable advances in detector technology are now poised to enable a similar revolution in the measurement of structure and fields in materials. Here we describe a high speed, high dynamic range imaging hybrid pixel array detector (EMPAD - electron microscope pixel array detector) for use in electron microscope applications, especially as a universal detector for scanning transmission electron microscopy. The in-pixel circuitry provides a 1,000,000:1 dynamic range within a single frame, allowing the direct electron beam to be imaged while still maintaining single electron sensitivity. A 1.1 kHz framing rate enables rapid data collection while scanning. The scattering is recorded on an absolute scale, so that information such as local sample thickness can be directly determined. By capturing the entire unsaturated diffraction pattern in scanning mode, the detector can simultaneously capture bright field, dark field, and phase contrast information, as well as being able to analyze the full scattering distribution, allowing true center-of-mass imaging for electric and magnetic field measurements, and opening the way for new multichannel imaging modes.

Powered by Eventact EMS