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Examination of Graphene in a Scanning Low Energy Electron Microscope
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SYSNO ASEP 0450818 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Ostatní články Title Examination of Graphene in a Scanning Low Energy Electron Microscope Author(s) Müllerová, Ilona (UPT-D) RID, SAI, ORCID
Mikmeková, Eliška (UPT-D) RID
Frank, Luděk (UPT-D) RID, SAI, ORCIDNumber of authors 3 Source Title Microscopy and Microanalysis. - : Cambridge University Press - ISSN 1431-9276
Roč. 21, S3 (2015), s. 29-30Number of pages 2 s. Publication form Print - P Language eng - English Country US - United States Keywords graphene ; LEEM Subject RIV JA - Electronics ; Optoelectronics, Electrical Engineering R&D Projects LO1212 GA MŠMT - Ministry of Education, Youth and Sports (MEYS) Institutional support UPT-D - RVO:68081731 DOI 10.1017/S143192761500094X Annotation Although graphene has been available and intensively studied for a full decade, new methods are still required for its examination and diagnostics. Even checking the continuity of layers and the reliable counting of layers of graphene and other 2D crystals should be easier to perform. Scanning low energy electron microscope (SLEEM) equipped with a cathode lens offers an innovative tool enabling one to see graphene samples at nanometer lateral resolution in both transmitted and reflected electrons and to count the number of layers. This diagnostics can be performed on freestanding graphene samples as well as on graphene grown on the surfaces of bulk substrates. The freestanding graphene samples were first examined in the standard vacuum high resolution SLEEM. Fig. 1 shows micrographs taken in the reflected electron (RE) as well as transmitted electron (TE) mode at several energies. The RE signal was composed of both secondary and backscattered electron emission, accelerated in the cathode lens field toward the detector. In the RE frames the maximum contrast between the graphene layers and lacey carbon appears at 1 keV and decreases toward higher and lower energies because of extending and shortening information depth, respectively. These images identify empty holes but do not reveal thicker islands of graphene. In the TE mode we do not see multilayer graphene islands above 100 eV. This fact underlines the suitability of very low energy electron microscopy for examination of 2D crystals. Interpretation challenges are presented by some details inverting their contrast more than once, see the arrow. These probably arise from contaminations that become charged. Workplace Institute of Scientific Instruments Contact Martina Šillerová, sillerova@ISIBrno.Cz, Tel.: 541 514 178 Year of Publishing 2016
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