Scanning Ultra-Low-Energy Electron Microscopy of 2D Crystals

0481338 - ÚPT 2018 CN eng A - Abstrakt
Mikmeková, Eliška - Paták, Aleš - Frank, Luděk - Sluyterman, S.
Scanning Ultra-Low-Energy Electron Microscopy of 2D Crystals.
BIT's 5th Annual Conference of AnalytiX-2017. Conference Abstract Book. Dalian: BIT Goup Global, 2017. s. 224.
[BIT's Annual Conference of AnalytiX-2017 /5./. 22.03.2017-24.03.2017, Fukuoka]
Institucionální podpora: RVO:68081731
Klíčová slova: ultra-Low-Energy Electron Microscopy * scanning * 2D Crystals
Obor OECD: Coating and films

Low kV surface scanning electron microscopy can be a powerful technique for the characterization of atomically thick materials such as graphene. Individual layers can be well distinguished in the range of units of eV. In the reflection mode, image signals at units of eV exhibit sharp changes in contrast between different thickness areas, so the number of layers can be determined from the number of local minima in the reflected signal within this energy range. The oscillations in reflectivity originate from interlayer states that occur in multilayered 2D crystals. Moreover, imaging at tens of eV also makes it possible to distinguish between under-layer or over-layer mechanisms of growth on selected substrates.
Unfortunately, a well-known problem can detrimentally affect the quality of results, namely specimen contamination. Even a small amount of hydrocarbon contamination can have a severe impact on the properties of samples. Common cleaning methods such as solvent rinsing, heating, electron bombardment and plasma etching all have their limitations. In particular, electron-induced cleaning involves numerous operating parameters (landing electron energy, electron dose, sample biasing, etc.) and can often damage the samples. On the other hand, it is an in-situ cleaning method and the use of slow electrons can eliminate the electron irradiation damage. Removal of absorbed molecules without irradiation damage of the samples has been observed.

Trvalý link: http://hdl.handle.net/11104/0276916