High-Mobility MoS2 Transistors Enabled by In2P3S9 Functional Dielectric Engineering and Interfacial Dipole Modulation

Abstract Interfacial disorder, threshold-voltage instability, and mobility degradation present critical roadblocks for two-dimensional (2D) electronics. Conventional deposited high-κ oxides often introduce damage and defect states, whereas standard van der Waals (vdW) dielectrics function primarily as passive encapsulation layers. Here, we demonstrate a functional vdW dielectric interface strategy using layered In2P3S9, a wide-bandgap (∼2.9 eV) material with a high dielectric constant (about 24), which unifies charge-transfer modulation, dielectric screening, and gate coupling within a single vdW transistor architecture. Driven by spontaneous charge redistribution and dipole formation at the MoS2/In2P3S9 interface, the threshold voltage shifts positively from −28 V to −2 V, achieving near-zero-gate operation. Concurrently, strong dielectric screening mitigates Coulomb scattering from substrate charged impurities, optimizing the subthreshold swing and enhancing the field-effect mobility from 18 to 130 cm2·V–1·s–1. Demonstrated across MoS2, SnS2, and ReS2 devices, this functional dielectric integration strategy offers a compact materials-design principle for next-generation 2D nanoelectronics.