Bandgap Extraction and Device Analysis of Ionic Liquid Gated WSe₂ Schottky Barrier Transistors

Through the careful study of ionic liquid gated WSe 2 Schottky barrier field-effect transistors as a function of flake thickness—referred to in the following as body thickness, t body —critical insights into the electrical properties of WSe 2 are gained. One finding is that the inverse subthreshold slope shows a clear dependence on body thickness, i . e ., an approximate square root dependent increase with t body, that provides evidence that injection into the WSe 2 channel is mediated by thermally assisted tunneling through the gate-controlled Schottky barriers at the source and drain. By employing our Schottky barrier model, a detailed experimental plot of the WSe 2 bandgap as a function of body thickness is obtained. We will discuss why the analysis employed here is critically dependent on the use of the above-mentioned ionic liquid gate and how device characteristics are analyzed in detail.