Improved Charge Transfer and Barrier Lowering across a Au–MoS₂ Interface through Insertion of a Layered Ca₂N Electride
2021
Kaadou, Fouad | Maassen, Jesse | Johnson, Erin R.
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.
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