Berlin 2015 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 39: Posters II (Topological insulators; Graphene; Spintronics and spin physics; Quantum information science)

HL 39.13: Poster

Dienstag, 17. März 2015, 14:00–20:00, Poster F

Quantitative transmission electron microscopy of two-dimensional transition metal dichalcogenides — •Florian Winkler¹, Amir H. Tavabi¹, Emrah Yucelen², Beata E. Kardynal³, and Rafal E. Dunin-Borkowski¹ — ¹Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute 5, Research Centre Jülich, Germany — ²FEI Company, Achtseweg Noord 5, 5600 KA Eindhoven, The Netherlands — ³Peter Grünberg Institute 9, Research Centre Jülich, Germany

Layered transition metal dichalcogenides (TMDs) have been the subject of intense research for applications in nanoelectronics. Strong spin-orbit interactions combined with a direct bandgap in monolayers of MX₂ (M: Mo, W; X: S, Se) have been shown to make TMDs very attractive for spintronics and valleytronics. The layered structures of TMDs make them ideal for quantitative studies using transmission electron microscopy (TEM), which can further be compared with device performance. Here, we study WSe₂ samples with thicknesses of between 1 and 4 monolayers using several quantitative TEM techniques, including off-axis electron holography and high-angle annular dark-field scanning TEM. We show that challenges associated with sample contamination, sample stability and and electron-beam-induced charging can be minimised through experimental design and a careful choice of imaging parameters. We perform statistical analyses of phase shifts measured using medium-resolution and high-resolution off-axis holography to measure the mean inner potentials of the samples and the numbers of S or Se atoms in individual atomic columns, respectively.