Improved Charge Transfer and Barrier Lowering across a Au–MoS<sub>2</sub> Interface through Insertion of a Layered Ca<sub>2</sub>N Electride
Fouad Kaadou, Jesse Maassen, Erin R. Johnson
Abstract
Despite immense promise, use of transition-metal dichalcogenides (TMDCs), such as MoS2, in electronics applications is hindered by the difficulties in forming effective metal contacts with low resistance. In this work, we propose insertion of a two-dimensional (2D) electride [Ca2N]+(e–) at a metal–TMDC interface to establish proper electrical contact. As a proof of concept, we consider the Au–MoS2 interface due to the presence of a van der Waals gap, which leads to a high tunneling barrier and strong Fermi-level pinning. Density-functional theory calculations predict nearly complete charge transfer from the electride surface states, resulting in a cationic [Ca2N]+ monolayer at the interface and metalization of the negatively doped MoS2. Thus, formation of the Au–Ca2N–MoS2 heterostructure eliminates both the tunneling and Schottky barriers, indicating that inserting a single 2D electride layer at metal–TMDC interfaces is a viable strategy to achieve proper Ohmic contacts in device manufacture.