Ionic gated WSe2 FETs: Towards transparent Schottky barriers

Abstract

In this article, we experimentally demonstrate for the first time high performance ionic liquid gated Schottky barrier WSe2 FETs with large current drive capabilities for both the electron and the hole branch. We also show that through proper scaling of the flake thickness, the Schottky barrier can be made transparent to the carrier injection and thus transforming the metal contacts into pseudo-Ohmic ones. We also analyzed the tunneling current through the Schottky barrier and compared it with numerical simulations in order to evaluate the potential of WSe2 for low power applications. WSe2 belongs to the family of two-dimensional layered semiconducting transition metal dichalcogenides (TMDs) which have received substantial attention in the device community as alternative channel materials to Si. [1] WSe2 is especially interesting since it shows ambipolar conduction due to the pinning of metal Fermi level close to the middle of the bandgap. [2] In addition, the relatively small carrier effective mass [3] of WSe2 in comparison to other TMDs makes this material appealing for low power tunneling devices.