Gate‐Tunable Electrical Transport in Thin 2M‐WS2 Flakes

Abstract

AbstractElectrolyte gating has been employed as an effective way to modulate the electronic properties of transition metal dichalcogenides (TMDs) by carrier doping over a wide range. Here, the carrier density of a new metastable phase of TMD material 2M‐WS2 is controlled by electrolyte gating to achieve reversible transitions between the superconducting state, metallic state, and insulating state. Pristine 2M‐WS2 has a superconducting transition temperature (Tc) of 8.9 K with a hole‐type carrier density of 9.05 × 1021 cm−3 at 100 K. A gate voltage (Vg) is applied between the sample and a side gate, which are both immersed in a droplet of gel‐like Li‐ion electrolyte (LiClO4 dissolved in polyethylene oxide matrix). When Vg = −3.5 V, the sample is in its pristine superconducting phase. With increasing Vg, the lithium ions gradually intercalate into the layered sample and tune it from a superconductor to an insulator. By precise tuning of Vg in this device, the entire phase diagram of 2M‐WS2 over a large range of carrier density is obtained.