Conformal Encapsulation of Wafer-Scale Molybdenum Disulfide Field-Effect Transistors by Plasma-Induced Molecular Polymerization

Molecular engineering of 2D transition-metal dichalcogenides (TMDs) is an effective strategy for tuning their electronic properties, enhancing metal-semiconductor contacts, and modulating charge carrier dynamics. However, scalable molecular engineering for fabricating wafer-scale 2D TMDs field-effect transistors (FETs) has been scarcely reported. Here, improved electrical performance in monolayer (1L)-MoS₂ FETs via allylamine polymer encapsulation, achieved by a plasma-induced molecule polymerization (PIMP) process with a low power of 5 W, is reported. Electrical measurement results confirm a weak n-doping effect in 1L-MoS₂, with which the doping concentrations could be adjusted from 1.12 × 10¹² to 5.17 × 10¹² cm^-2. A high-resolution transmission electron microscopy (HRTEM) image reveals an ultra-thin and dense allylamine polymer layer with a thickness of 3.7 nm, uniformly coated on the surface of the 1L-MoS₂ under the PIMP process for 20 s. The conformal polymerized layer not only reduces the hysteresis loops of the 1L-MoS₂ FETs but also enhances environmental stability while preserving the transistor characteristics for ≈9 months. Additionally, 1L-MoS₂ FET arrays with over 5000 devices on a large scale, revealing high uniformity and reproducibility using the PIMP process, which offers a practical and scalable strategy for wafer-scale optimization of 2D FETs, are demonstrated.