Ohmic contacts of the two-dimensional Ca 2 N/MoS 2 donor-acceptor heterostructure.

In the current stage, conventional silicon-based devices are suffering from the scaling limits and the Fermi level pinning effect. Therefore, looking for low-resistance metal contacts for semiconductors has become one of the most important topics, and two-dimensional (2D) metal/semiconductor contacts turn out to be highly interesting. Alternatively, the Schottky barrier and the tunneling barrier impede their practical applications. In this work, we propose a new strategy for reducing the contact potential barrier by constructing a donor-acceptor heterostructure, that is, Ca 2 N/MoS 2 with Ca 2 N being a 2D electrene material with a significantly small work function and a rather high carrier concentration. The quasi-bond interaction of the heterostructure avoids the formation of a Fermi level pinning effect and gives rise to high tunneling probability. An excellent n-type Ohmic contact form between Ca 2 N and MoS 2 monolayers, with a 100% tunneling probability and a perfect linear I - V curve, and large lateral band bending also demonstrates the good performance of the contact. We verify a fascinating phenomenon that Ca 2 N can trigger the phase transition of MoS 2 from 2H to 1T'. In addition, we also identify that Ohmic contacts can be formed between Ca 2 N and other 2D transition metal dichalcogenides (TMDCs), including WS 2 , MoSe 2 , WSe 2 , and MoTe 2 .