Intrinsic limit of contact resistance in the lateral heterostructure of metallic and semiconducting PtSe ₂

High contact resistance (R_c) limits the ultimate potential of two-dimensional (2-D) materials for future devices. To resolve the R_c 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 R_c in the metallic-semiconducting PtSe₂ heterostructure through density functional theory (DFT) combined with non-equilibrium Green's function (NEGF). Compared with R_c in the 1T-2H MoS₂ heterostructure, the multilayer-monolayer PtSe₂ heterostructure can offer much lower R_c due to the better capability of providing more transmission modes.