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DS: Fachverband Dünne Schichten

DS 11: Poster I (joint session DS/MM/O)

DS 11.5: Poster

Wednesday, March 20, 2024, 17:00–19:00, Poster B

Optimizing electrical transport and SAW propagation in molybdenum disulfide — •Noah Spitzner¹, Pai Zhao¹, Renrong Liang², Chithra Sharma¹, Lars Tiemann¹, and Robert Blick¹ — ¹Center of Hybrid Nanostructures, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg — ²School of Integrated Circuits, Tsinghua University, 100083 Beijing, China

Few-layered and monolayer MoS₂ has gained increasing significance in recent years, due to its large band gap of up to 1.9 eV at the K and K^′ valley of the hexagonal Brillouin zone. Surface acoustic waves (SAW) and transport measurements allow non destructive probing of the physics governing the material.

In this work we exfoliated MoS₂ flakes of a few layers onto a specially tailored substrate with LiNbO₃ as piezoelectric top layer. We can pass surface acoustic waves through the MoS₂ flake via an interdigitated transducer (IDT) electrode configuration and study the electrical response. To facilitate electron transport at low temperatures, liquid nitrogen physical vapor deposition (LNPVD) was utilized to deposit the contact metals. The cooled deposition reduces Fermi level pinning (FLP) in the contact interface and empowers us to measure longitudinal and transversal voltages with better contact quality.

Under acoustic excitation at 4.2 K, we observed acoustic currents and voltages in MoS₂ that depend on the power and frequency of the SAW. Hence, we were able to observe the acoustoelectric and acoustogalvanic effect. We also studied magnetotransport under perpendicular magnetic fields and the weak localization phenomenon.