Sub-5 nm p-Type 1T/2H ZrCl2 Edge-Contact Field-Effect Transistor: A Phase-Engineered High-Performance Device

Phase engineering provides a doping-free strategy for constructing metal/semiconductor homojunctions in two-dimensional (2D) field-effect transistors (FETs), thereby mitigating contact resistance and Fermi-level pinning. The quantum transport properties of p-type 1 T/2H ZrCl2 edge-contact FETs with different channel lengths were systematically investigated using density functional theory combined with the nonequilibrium Green's function method. The results demonstrate that channel length plays a decisive role in suppressing off-state leakage current. When the channel length is reduced below 4.019 nm, the tunneling transmission increases substantially, resulting in excessive off-state leakage that no longer satisfies the International Technology Roadmap for Semiconductors (ITRS) high-performance (HP) specification. At a channel length of 4.019 nm, the device achieves an on-state current of 1227 μA/μm, an off-state current of 0.056 μA/μm, an on/off current ratio of 2.19 × 104, and a subthreshold swing of 84 mV/dec, meeting all HP performance targets. These results establish 4.019 nm as the physical scaling limit of the channel length for the proposed ideal 1T/2H ZrCl2 p-type edge-contact FET and provide theoretical reference for the design of phase-engineered 2D transistors at the sub-5 nm technology node.