Intrinsic limit of contact resistance in the lateral heterostructure of metallic and semiconducting PtSe2

High contact resistance (Rc) limits the ultimate potential of two-dimensional (2-D) materials for future devices. To resolve the Rc problem, forming metallic 1T phase MoS2 locally in the semiconducting 2H phase MoS2 has been successfully demonstrated to use the 1T phase as source/drain electrodes in field effect transistors (FETs). However, the long-term stability of the 1T phase MoS2 still remains as an issue. Recently, an unusual thickness-modulated phase transition from semiconducting to metallic has been experimentally observed in 2-D material PtSe2. Metallic multilayer PtSe2 and semiconducting monolayer PtSe2 can be used as source/drain electrodes and channel, respectively, in FETs. Here, we present a theoretical study on the intrinsic lower limit of Rc in the metallic-semiconducting PtSe2 heterostructure through density functional theory (DFT) combined with non-equilibrium Green's function (NEGF). Compared with Rc in the 1T-2H MoS2 heterostructure, the multilayer-monolayer PtSe2 heterostructure can offer much lower Rc due to the better capability of providing more transmission modes.