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

Through the careful study of ionic liquid gated WSe₂ 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 WSe₂ 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 WSe₂ 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 WSe₂ 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.