Reinterpreting Low Resistance in Sb–MoS₂ Ohmic Contacts by Means of Ab Initio Transport Simulations

Abstract

By using an in-house nonequilibrium Green's function (NEGF)-based ab initio simulator, we investigate the physical mechanisms driving the Sb(0112)-MoS 2 system to exhibit the lowest reported contact resistance, R C = 42 • µm, to the 2-D semiconductor MoS 2 . We can find that the transport from the hybridized bands in the Sb-MoS 2 heterojunction is quite ineffective and that the back-gateinduced doping of MoS 2 in the contact region is crucial to explain the experiments. In fact, by accounting in our ab initio simulations for the presence of a back gate according to the experiments, it is possible to match the band structure of the MoS 2 in the Sb-MoS 2 heterojunction with that of the external MoS 2 layer, which drastically increases the electronic transmission throughout the contact, and ultimately pushes R C close to the quantum limit. Furthermore, we extend the applicability of our previously demonstrated simulation methodology and thus investigate a field-effect transistors (FETs)-like device including an ab initio description of the carrier injection at the Sb-MoS 2 contact.