Energy-Resolved EBSD using a Monolithic Direct Electron Detector

TL;DR

This paper presents a novel energy-resolved EBSD technique using a monolithic direct electron detector, enabling detailed energy spectra measurement of backscattered electrons and improving pattern analysis.

Contribution

It introduces a new method for energy-resolved EBSD with single-electron energy measurement, enhancing pattern clarity and understanding of backscattering processes.

Findings

Broad BSE energy distribution observed up to 3 keV

Energy filtering improves pattern clarity and detail

High-energy BSEs dominate Kikuchi pattern formation

Abstract

Accurate quantification of the energy distribution of backscattered electrons (BSEs) contributing to electron backscatter diffraction (EBSD) patterns remains as an active challenge. This study introduces an energy-resolved EBSD methodology based on a monolithic active pixel sensor direct electron detector and an electron-counting algorithm to enable the energy quantification of individual BSEs, providing direct measurements of electron energy spectra within diffraction patterns. Following detector calibration of the detector signal as a function of primary beam energy, measurements using a 12 keV primary beam on Si(100) reveal a broad BSE energy distribution across the diffraction pattern, extending down to 3 keV. Furthermore, an angular dependence in the weighted average BSE energy is observed, closely matching predictions from Monte Carlo simulations. Pixel-resolved energy maps reveal subtle modulations at Kikuchi band edges, offering insights into the backscattering process. By applying energy filtering within spectral windows as narrow as 2 keV centered on the primary beam energy, significant enhancement in pattern clarity and high-frequency detail is observed. Notably, BSEs in the 9--10 keV range dominate Kikuchi pattern formation, while BSEs in the 2--8 keV range, despite having undergone substantial energy loss, still produce Kikuchi patterns. By enabling energy determination at the single-electron level, this approach introduces a versatile tool-set for expanding the quantitative capabilities of EBSD, thereby offering the potential to deepen the understanding of diffraction contrast mechanisms and to advance the precision of crystallographic measurements.