2D/2D Electrical Contacts in the Monolayer WSe₂ Transistors: A First-Principles Study

Seeking a proper electrode contact for two-dimensional materials such as monolayer (ML) WSe₂ is of vital importance for ultrathin electronic devices. Here, we investigate a series of novel 2D/2D electrical contacts in sub-10 nm ML WSe₂ transistors by first-principles calculations. We find that the NbSe₂, borophene, Mo₂CF₂, and Mo₂CO₂ electrodes form p-type Ohmic contact with ML WSe₂, while the Ti₂C(OH)₂ forms n-type Ohmic contact and Ti₂C forms n-type Schottky contact. Particularly, the on-current, delay time, and power dissipation for the NbSe₂ and Ti₂C(OH)₂ electrodes in the transistors approach the international technology roadmap for semiconductors (ITRS) 2013 requirements for high-performance (low-power) applications at the gate length of 5 nm (7 nm). A formalism is proposed to analyze the 2D/2D electrical contacts from the device application viewpoint, thereby providing guidelines for the design of future 2D semiconductor-based devices.