Electron backscattered diffraction using a new monolithic direct detector: High resolution and fast acquisition

A monolithic active pixel sensor based direct detector that is optimized for the primary beam energies in scanning electron microscopes is implemented for electron back-scattered diffraction (EBSD) applications. The high detection efficiency of the detector and its large array of pixels allow sensitive and accurate detection of Kikuchi bands arising from primary electron beam excitation energies of 4 keV to 28 keV, with the optimal contrast occurring in the range of 8-16 keV. The diffraction pattern acquisition speed is substantially improved via a sparse sampling mode, resulting from the acquisition of a reduced number of pixels on the detector. Standard inpainting algorithms are implemented to effectively estimate the information in the skipped regions in the acquired diffraction pattern. For EBSD mapping, an acquisition speed as high as 5988 scan points per second is demonstrated, with a tolerable fraction of indexed points and accuracy. The collective capabilities spanning from high angular resolution EBSD patterns to high speed pattern acquisition are achieved on the same detector, facilitating simultaneous detection modalities that enable a multitude of advanced EBSD applications, including lattice strain mapping, structural refinement, low-dose characterization, 3D-EBSD and dynamic in situ EBSD.

Automated summary

A monolithic active pixel sensor based direct detector optimized for scanning electron microscope primary beam energies is used for electron back-scattered diffraction (EBSD) applications. The detector provides high detection efficiency and a large array of pixels, allowing sensitive and accurate detection of Kikuchi bands, with optimal contrast occurring in the 8-16 keV range. The diffraction pattern acquisition speed is greatly improved through sparse sampling mode and inpainting algorithms, while achieving high-speed EBSD mapping.