MRI: Development of an ultrafast, ultrasensitive, and high resolution direct electron detector for next-generation electron back-scattered diffraction of metallic and beam-sensitiv

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Electron back-scattered diffraction (EBSD) has evolved into a widespread and powerful characterization technique for the mapping and analysis of phases in materials, providing key information about crystal orientation, morphologies, lattice strain, topology, and crystallographic texture. The advent of direct electron detection that circumvents inefficient conversion between electrons and photons has revolutionized the field of transmission electron microscopy owing to single-electron sensitivity for low-dose imaging and ultrafast detection for time-resolved studies, but its use in scanning electron microscopes (SEMs) is in its infancy. An award is made to the University of California Santa Barbara to develop an ultrafast and ultrasensitive direct electron EBSD instrument for the widely accessible SEM platform, providing a rich opportunity for materials research that are hindered by electron beam damage and temporal limitations of detectors. The development project improves on the state-of-the-art EBSD acquisition speed and enhances the sensitivity through a new sensor design, unlocking the most vexing challenges in the rapid 3D characterization of additively manufactured materials and emerging dose-sensitive energy storage and conversion materials plagued by beam damage. The award will ensure engagement with the community and early-career researchers via a yearly open house hosted by the shared user facility, as well as with REU and RET projects through partnerships with the Materials Research Laboratory and the Quantum Foundry at UC Santa Barbara. The developed instrumentation and simulation tools will also be integrated with the Center for Scientific Computing, which promotes the effective use of High Performance Computing in the research and teaching environment.The next-generation direct-detection EBSD instrument will be optimized for electron beam energies of 3kV to 30kV with single-electron sensitivity, and a small sensor form factor permitting flexible location within the microscope chamber. For materials that are damage-prone, such as organic crystalline materials, limiting the electron dose is critical and detection yield becomes paramount, especially at low energies. The developed instrument will enable the detection of rich material information encoded in electron diffraction, circumventing longstanding issues of low-damage threshold and weak scattering signals. Metallic alloys and battery materials also benefit from high detection sensitivity and low-kV operation, revealing structural features such as dislocation cells in additively manufactured materials and enabling the evolution of microstructure at rates that can keep up with in operando device observations.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.