Superconductivity Series in Transition Metal Dichalcogenides by Ionic Gating

摘要

Functionalities of two-dimensional (2D) crystals based on semiconducting transition metal dichalcogenides (TMDs) have now stemmed from simple field effect transistors (FETs) to a variety of electronic and opto-valleytronic devices, and even to superconductivity. Among them, superconductivity is the least studied property in TMDs due to methodological difficulty accessing it in different TMD species. Here, we report the systematic study of superconductivity in MoSe₂, MoTe₂ and WS₂ by ionic gating in different regimes. Electrostatic gating using ionic liquid was able to induce superconductivity in MoSe₂ but not in MoTe₂ because of inefficient electron accumulation limited by electronic band alignment. Alternative gating using KClO₄/polyethylene glycol enabled a crossover from surface doping to bulk doping, which induced superconductivities in MoTe₂ and WS₂ electrochemically. These new varieties greatly enriched the TMD superconductor families and unveiled critical methodology to expand the capability of ionic gating to other materials.