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.