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

By using an in-house nonequilibrium Green’s function (NEGF)-based ab initio simulator, we investigate the physical mechanisms driving the Sb( ${01}\overline {{1}}{2}$ )–MoS2 system to exhibit the lowest reported contact resistance, ${R}_{C}={42} \Omega \cdot \mu \text{m}$ , to the 2-D semiconductor MoS2. We can find that the transport from the hybridized bands in the Sb–MoS2 heterojunction is quite ineffective and that the back-gate-induced doping of MoS2 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 MoS2 in the Sb–MoS2 heterojunction with that of the external MoS2 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–MoS2 contact.