STEM modes in SEM – simulations and experiments

0481585 - ÚPT 2018 RIV HR eng C - Konferenční příspěvek (zahraniční konf.)
Konvalina, Ivo - Paták, Aleš - Mika, Filip - Müllerová, Ilona
STEM modes in SEM – simulations and experiments.
13th Multinational Congress on Microscopy: Book of Abstracts. Zagreb: Ruder Bošković Institute, Croatian Microscopy Society, 2017 - (Gajović, A.; Weber, I.; Kovačević, G.; Čadež, V.; Šegota, S.; Peharec Štefanić, P.; Vidoš, A.), s. 140-141. ISBN 978-953-7941-19-2.
[Multinational Congress on Microscopy /13./. Rovinj (HR), 24.09.2017-29.09.2017]
Grant CEP: GA TA ČR(CZ) TE01020118
Institucionální podpora: RVO:68081731
Klíčová slova: STEM detector * trajectory simulations * cathode lens * collection efficiency
Obor OECD: Electrical and electronic engineering

The semiconductor STEM detector in the Magellan 400 FEG SEM microscope (www.fei.com) is used to detect transmitted electrons (TE) and allows observing samples in four imaging modes. Two modes of objective lens, namely HR (high resolution) and UHR (ultra high resolution), differ by their resolution and by the presence or absence of a magnetic field around the sample. If the deceleration mode is chosen, cathode lens (CL) field is added, and two further microscope modes can be obtained. The aim of this work is to study the trajectories of the TEs in each mode with regard to their angular and energy distribution. The HR and HR + CL mode is without magnetic field around the sample, for that reason the electrons retain their angular information. In addition, the electrostatic field between the sample and the STEM detector collimates the electrons towards the optical axis. We can detect TEs emitted at a large polar angles with respect to the optical axis. On the other hand, for UHR and UHR + CL modes, the sample is placed in a strong magnetic field. The electrons under the influence of the magnetic field have spiral trajectories and can cross the optical axis plane several times during their path to the detector, thus angular information is not simply interpretable.
Trvalý link: http://hdl.handle.net/11104/0277129