Thickness dependent interlayer transport in vertical MoS2 Josephson junctions

TL;DR

This study investigates how the thickness of MoS2 layers affects Josephson coupling and Andreev reflections in vertical MoS2-MoRe junctions, revealing significant variations in critical current and quasiparticle gaps.

Contribution

It demonstrates the fabrication of high-transparency vertical MoS2 Josephson junctions with thickness-dependent transport properties using oxide-free methods.

Findings

Single and bilayer MoS2 show large critical currents and MAR features.

Thicker (3-4 layer) MoS2 devices have much lower critical currents and reduced gaps.

Device architecture can be extended to other 2D materials.

Abstract

We report on observations of thickness dependent Josephson coupling and multiple Andreev reflections (MAR) in vertically stacked molybdenum disulfide (MoS2) - molybdenum rhenium (MoRe) Josephson junctions. MoRe, a chemically inert superconductor, allows for oxide free fabrication of high transparency vertical MoS2 devices. Single and bilayer MoS2 junctions display relatively large critical currents (up to 2.5 uA) and the appearance of sub-gap structure given by MAR. In three and four layer thick devices we observe orders of magnitude lower critical currents (sub-nA) and reduced quasiparticle gaps due to proximitized MoS2 layers in contact with MoRe. We anticipate that this device architecture could be easily extended to other 2D materials.