The performance evaluation of direct detection electron energy-loss spectroscopy at 200 kV and 80 kV accelerating voltages

Shaobo Cheng; Alexandre Pofelski; Paolo Longo; Ray D Twesten; Yimei Zhu; Gianluigi A Botton

doi:10.1016/j.ultramic.2020.112942

The performance evaluation of direct detection electron energy-loss spectroscopy at 200 kV and 80 kV accelerating voltages

Ultramicroscopy. 2020 May:212:112942. doi: 10.1016/j.ultramic.2020.112942. Epub 2020 Jan 22.

Authors

Shaobo Cheng¹, Alexandre Pofelski², Paolo Longo³, Ray D Twesten³, Yimei Zhu⁴, Gianluigi A Botton⁵

Affiliations

¹ Department of Materials Science and Engineering and Canadian Centre for Electron Microscopy, McMaster University, Hamilton, ON L8S 4M1, Canada; Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, NY 11973 USA.
² Department of Materials Science and Engineering and Canadian Centre for Electron Microscopy, McMaster University, Hamilton, ON L8S 4M1, Canada.
³ Gatan Inc., Pleasanton, CA 94588, USA.
⁴ Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, NY 11973 USA.
⁵ Department of Materials Science and Engineering and Canadian Centre for Electron Microscopy, McMaster University, Hamilton, ON L8S 4M1, Canada. Electronic address: gbotton@mcmaster.ca.

PMID: 32114314
DOI: 10.1016/j.ultramic.2020.112942

Abstract

Direct electron detectors (DeDs) have been widely used for imaging studies because of their higher beam sensitivity, lower noise, improved pixel resolution, etc. However, there have been limited studies related to the performance in spectroscopic applications for the direct electron detection. Hereby, taking the advantage of the DeD installed on a high-performance electron energy-loss spectrometer, we systematically studied the performance of a DeD (Gatan's K2 IS) fitted on an aberration-corrected transmission electron microscope (TEM) equipped with an electron monochromator. Using SrTiO₃ as the model system, the point spread function in the zero-loss region of the spectrum and the performance for core loss spectroscopy have been investigated under both 200 kV and 80 kV operating conditions. We demonstrate that the K2 detector can achieve an overall better performance at 200 kV than a charge coupled device (CCD) detector. At 80 kV, the K2 DeD is still better than a CCD, except for the relative broad tails of the zero-loss peak. The signal-to-noise ratio is very close for DeD and CCD under 80 kV. Based on our data obtained at different operating voltages, it is clear that DeD will benefit the microscopy community and boost the development of cutting-edge materials science studies by pushing the frontiers in electron energy-loss spectroscopy.

Keywords: Direct electron detector; Electron energy-loss spectroscopy; SrTiO(3); Transmission electron microscopy.