Ohmic MXene Contacts for Symmetric <i>p</i>- and <i>n</i>-type Monolayer WSe₂ Schottky Barrier Field-Effect Transistors

Abstract

Achieving Ohmic-contact electrodes for two-dimensional (2D) Schottky barrier field-effect transistors (SBFETs) and symmetric p- and n-type performances are two pivotal aspects of 2D-based integrated circuits. As 2D WSe2 possesses both high electron and hole mobilities, we choose monolayer (ML) WSe2 as the channel and functionalized Nb2C with a similar lattice and a broad scope work function as the electrode. The contact properties and device performances are studied theoretically at the ab initio level. P- and n-type Ohmic contacts are achieved with high- and low-WF metals, i.e., Nb2CO2 and Nb2C(OH)2, respectively, and the interfaces are both clean without metal-induced gap states. The optimal ML WSe2 SBFETs with Nb2CO2 and Nb2C(OH)2 electrodes possess symmetric p- and n-type Ion values of 1542/1823 and 1688/2173 μA/μm, respectively, for low-power/high-performance (LP/HP) applications with a gate length of 3 nm and a supply voltage of 0.5 V, surpassing the International Roadmap for Device and Systems LP/HP target. This study suggested potential Ohmic-contact electrodes for symmetric p- and n-type ML WSe2 SBFETs in the post-Si era.