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L. Pirker

Publications and source records attributed to L. Pirker.

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Material transfer and contact optimization in MoS2 nanotube devices

While the promise of clean and defect-free $\textrm{MoS}_{2}$ nanotubes as quantum electronic devices is obvious, ranging from strong spin-orbit interaction to intrinsic superconductivity, device fabrication still poses considerable challenges. Deterministic transfer of transition metal dichalcogenide nanomaterials and transparent contacts to the nanomaterials are nowadays highly active topics of research, both with fundamental research and applications in mind. Contamination from transport agents as well as surface adsorbates and surface charges play a critical role for device performance. Many techniques have been proposed to address these topics for transition metal dichalcogenides in general. Here, we analyse their usage for the transfer based fabrication of $\textrm{MoS}_{2}$ nanotube devices. Further, we compare different contact materials in order to avoid the formation of a Schottky barrier.

cond-mat.mes-hall

Modulations of the Work Function and Morphology of a Single MoS2 Nanotube by Charge Injection

A current was injected into a single MoS2 nanotube using an atomic-force-microscopy probe. The trapped electrons and holes caused a partial collapse of the nanotube and its helical twisting. The topography changes can be explained by the reverse piezoelectric effect, the theory of which was proposed for chiral nanostructures. Work-function modifications were observed, which were dependent on the polarity of the injected carriers.

cond-mat.mes-hall

Non-Destructive Low-Temperature Contacts to MoS2 Nanoribbon and Nanotube Quantum Dots

Molybdenum disulfide nanoribbons and nanotubes are quasi-1D semiconductors with strong spin-orbit interaction, a nanomaterial highly promising for quantum electronic applications. Here, it is demonstrated that a bismuth semimetal layer between the contact metal and this nanomaterial strongly improves the properties of the contacts. Two-point resistances on the order of 100k$Ω$ are observed at room temperature. At cryogenic temperature, Coulomb blockade is visible. The resulting stability diagrams indicate a marked absence of trap states at the contacts and the corresponding disorder, compared to previous devices that use low-work-function metals as contacts. Single-level quantum transport is observed at temperatures below 100mK.

cond-mat.mes-hall