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O: Fachverband Oberflächenphysik

O 63: Focus Session: Charge Transport at Surfaces and Nanostructures with Multi-probe Techniques

O 63.6: Poster

Dienstag, 21. März 2017, 18:30–20:30, P2-OG3

Electronic Transport Measurements of 2-Dimensional Systems with a 4-Probe STM — •Tim Flatten¹, Sven Borghardt², Frank Matthes¹, Beata Kardynal², Daniel E. Bürgler¹, and Claus M. Schneider¹ — ¹Peter Grünberg Institut, Electronic Properties (PGI-6), Forschungszentrum Jülich — ²Peter Grünberg Institut, Semiconductor Nanoelectronics (PGI-9), Forschungszentrum Jülich

The recent emergence of 2-dimensional materials such as the transition metal dichalcogenides (TMD) requires new measurement techniques for exploring their physical properties. TMDs are interesting due to their large variety of electric properties ranging from insulating and semiconducting with direct or indirect band gap to metallic behavior depending on their composition and thickness. We employ a 4-probe scanning tunneling microscope (4-probe STM) operating in ultra-high vacuum (UHV) and at temperatures down to 5 K to combine STM with lateral 4-probe transport measurements. A top-mounted scanning electron microscope (SEM) enables positioning of the 4 independently driven STM tips on a sub-micrometer scale. We investigate the influence of ex-situ sample preparation and in-situ treatment on the surface morphology and cleanness by STM imaging and measure their effect on the electronic transport properties of single TMD flakes. In first steps, we perform scanning tunneling spectroscopy (STS) on single monolayer MoSe₂ flakes adsorbed on various insulating substrates to measure the dependence of their electronic band gap on the substrate properties.