Electrochemical-Etching Approach to Achieving Ultrathin FeSe Films

Abstract

Electric double layer transistor (EDLT) has attracted attentions over the decade as a useful tool to induce and control fascinating many physical properties at two dimensional (2D) materials surface based on its giant capacitance. This paper highlights another aspect of EDLT : electrochemical reaction as a method to achieve ultrathin films. Precise tuning of reactivity of electrochemical etching between ionic liquid and solid surface makes it possible to peel off 2D materials layer-by-layer. This technique was applied to an iron-based superconductor FeSe in EDLT towards the observation of high temperature superconductivity in ultra-thin film form.