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

High contact resistance (R) limits the ultimate potential of two-dimensional (2-D) materials for future devices. To resolve the R problem, forming metallic 1T phase MoS locally in the semiconducting 2H phase MoS 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 MoS still remains as an issue. Recently, an unusual thickness-modulated phase transition from semiconducting to metallic has been experimentally observed in 2-D material PtSe. Metallic multilayer PtSe and semiconducting monolayer PtSe 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 in the metallic-semiconducting PtSe heterostructure through density functional theory (DFT) combined with non-equilibrium Green's function (NEGF). Compared with R in the 1T-2H MoS heterostructure, the multilayer-monolayer PtSe heterostructure can offer much lower R due to the better capability of providing more transmission modes.