Fig. 1: Tunnel junction architecture and tunneling spectra.
From: The transition-metal-dichalcogenide family as a superconductor tuned by charge density wave strength
a Optical microscope image of a typical tunneling device. The superconductor TaS2 is outlined in blue and the semiconductor MoS2 in red. Scale bar: 10 μm. b Simplified schematic of a tunnel junction. TaS2 is placed on a SiO2 substrate, and partly covered with a MoS2 barrier. Ti/Au electrodes are evaporated over the heterostructure (for tunneling contacts) and also on the bare TaS2 flake (for Ohmic drain contacts). The current path upon application of voltage using the electrodes is indicated by dashed arrows. c Cross-section of a 4-layer junction taken in a scanning transmission electron microscope (STEM). Ta atoms are easily distinguishable as bright dots. A 3-layer MoS2 barrier is visible on top. Scale bar: 2 nm. d Representative tunneling spectra at base temperature (≈25 mK) of TaS2 of different thicknesses. All devices show a hard gap, with diminishing gap width towards thicker samples. Curves are vertically offset for clarity.
