Study of the coherence of the primary beam in the low energy scanning electron microscope

0448612 - ÚPT 2016 DE eng C - Konferenční příspěvek (zahraniční konf.)
Řiháček, Tomáš - Mika, Filip - Matějka, Milan - Krátký, Stanislav - Müllerová, Ilona
Study of the coherence of the primary beam in the low energy scanning electron microscope.
MC 2015. Microscopy Conference Proceedings. Göttingen: DGE, 2015, s. 611-612.
[Microscopy Conference 2015. Göttingen (DE), 06.09.2015-11.09.2015]
Grant CEP: GA TA ČR(CZ) TE01020118
Institucionální podpora: RVO:68081731
Klíčová slova: scanning electron microscope * coherence of the primary beam
Kód oboru RIV: JA - Elektronika a optoelektronika, elektrotechnika

Coherence of an electron beam is an important characteristic in a transmission electron microscope (TEM). It can be measured simply by analyzing the interference fringes in a diffraction pattern. On the other hand, the coherence of the beam is usually not important for standard applications of a scanning electron microscope (SEM). Nevertheless it can be of importance for some specific cases. The aim of this experiment is to find out whether the coherence of our SEM beam is high enough to enable us to perform a diffraction experiment at low energies (E = 350 - 2000 eV) which would enable us to create an electron vortex beam with of tens of keV. Some complications with the visualization of a diffraction pattern arise because SEM does not allow observing the pattern directly because of the scanning of the electron beam. Therefore the usual TEM diffraction techniques cannot be used. One way to get the resulting intensity profile is proposed in. We therefore make use of an experimental setup similar to that used in which is depicted in Figure 1. Our experiment was adapted for the SEM microscope FEI Magellan 400. The grating is carried by the retractable mechanism of a CBS detector which is placed below the pole piece of the objective lens where the diffraction of the primary beam takes place while the beam itself is focused to the specimen plane. The imaging of a diffraction pattern is achieved by scanning the beam across a specimen which consists of a contrasting vertical stripe on a dark background. For this purpose we have chosen a golden stripe on a carbon substrate. Secondary electrons are then collected with the standard side Everhart-Thornley (ET) detector.
Trvalý link: http://hdl.handle.net/11104/0250357