Berlin 2024 – scientific programme
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O: Fachverband Oberflächenphysik
O 63: Poster DS (joint session DS/MM/O)
O 63.5: 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.
Keywords: Van der Waals Material; Molybdenum Disulfide; Surface Acoustic Wave; Magnetotransport; Contact Fabrication