Device Transport Characteristics of Monolayer SnS₂ and HfS₂ Field-Effect Transistors with Semimetal Contacts

Atomically thin two-dimensional (2D) semiconductors with moderate band gaps have shown great potential as semiconducting materials for constructing high-performance transistors and integrated circuits. However, the untunable Schottky barrier height (SBH) and strong Fermi level pinning (FLP) at the metal/semiconductor interface result in significant contact resistance in 2D transistors, hindering device scaling and performance improvements. In this study, we present a comprehensive analysis of the interface contact and device transport properties between semimetallic bismuth (Bi), antimony (Sb), arsenic (As), and semiconducting monolayer SnS2, HfS2, and ZrS2. Our first-principles results demonstrate that ideal n-type Ohmic contacts and small interlayer tunnel barriers can be formed at the electrode/channel interfaces. Moreover, 5.1 nm SnS2 FETs with direct Bi, Sb, and As electrode contacts exhibit ultralow resistance values of 26.83–57.91 Ω μm and a high on-state current of 970.74–1640.74 nA/nm, satisfying the application requirements of the International Roadmap for Devices and Systems (IRDS) for high-performance transistors in 2028. These findings suggest that semimetals Bi, Sb, and As are potential electrode materials for ultrashort 2D transition metal dichalcogenide (TMDC) channels and could benefit the design of high-performance transistors in the post-Moore era.