High-efficiency detector of secondary and backscattered electrons for low-dose imaging in the ESEM

0489530 - ÚPT 2019 RIV NL eng J - Journal Article
Neděla, Vilém - Tihlaříková, Eva - Runštuk, Jiří - Hudec, Jiří
High-efficiency detector of secondary and backscattered electrons for low-dose imaging in the ESEM.
Ultramicroscopy. Roč. 184A, JAN (2018), s. 1-11. ISSN 0304-3991. E-ISSN 1879-2723
R&D Projects: GA MŠMT(CZ) LO1212; GA MŠMT ED0017/01/01
Institutional support: RVO:68081731
Keywords : detectors * scintillators * low-dose imaging * energy filtration * MC simulations
OECD category: Electrical and electronic engineering
Impact factor: 2.644, year: 2018

A new Combined System for high-efficiency detection of Secondary and Backscattered Electrons (CSSBE) in the ESEM consists of three detectors: an ionisation SE detector, an improved scintillation BSE detector, and a new Ionisation Secondary Electron Detector with an electrostatic Separator (ISEDS). The ISEDS optimizes conditions for electron-gas ionisation phenomena in the ESEM to achieve a strongly amplified signal from the secondary electrons with a minimal contribution from backscattered and beam electrons. For this purpose, it is originally equipped with an electrostatic separator, which focuses signal electrons towards a detection electrode and controls the concentration of positive ions above the sample. The working principle of the ISEDS is explained by simulations of signal electron trajectories in gas using the EOD program with our Monte Carlo module. The ability to detect the signal electrons in a selected range of energies is described with Geant4 Monte Carlo simulations of electron-solid interactions and proven by experimental results. High-efficiency detection of the ISEDS is demonstrated by imaging a low atomic number sample under a reduced beam energy of 5 keV, very low beam currents of up to 0.2 pA, and gas pressure of hundreds of Pa.
Permanent Link: http://hdl.handle.net/11104/0283928