Scalable Integration of Single-Crystalline Ag Nanosheets for Threshold Voltage Engineering in Oxide Thin-Film Transistors

Amorphous oxide semiconductor-based thin-film transistors (TFTs), particularly those utilizing indium gallium zinc oxide (IGZO), have garnered significant attention for next-generation display backplanes and flexible electronics. However, the precise and reliable modulation of threshold voltage (V_th) remains a persistent challenge, often requiring doping or vacancy engineering approaches that compromise process uniformity and device reliability. In this study, we introduce a scalable and low-temperature strategy for V_thtuning via the incorporation of two-dimensional (2D), single-crystalline silver nanosheets (Ag NSs) within the IGZO channel. These quasi-two-dimensional nanostructures have nanometer-scale thickness and lateral single crystallinity and are assembled using an ultrasonic-driven solution process that allows tunable coverage over large-area substrates. By varying Ag NS coverage up to 6.8%, we achieve a systematic and reproducible positive shift in V_th, with minimal degradation in mobility, on/off ratio, and subthreshold swing. Mechanistic studies using X-ray photoelectron spectroscopy and electrical bias stress testing reveal that the modulation arises from Schottky barrier formation and electrostatic screening at the Ag–IGZO interface rather than from modulation of oxygen vacancy concentrations. Devices incorporating Ag NSs exhibit excellent stability, with minimal hysteresis (ΔV_th≈ 1 V), negligible parameter drift under a ±20 V gate bias stress for 60 min, and long-term retention after 390 days of ambient storage. To validate the circuit-level applicability of this method, we fabricated depletion-load NMOS inverters combining pristine and Ag NS-modified IGZO TFTs, wherein the switching threshold could be finely tuned via the Ag NS coverage. This work demonstrates a wafer-compatible and solution-processable route to deterministic V_thengineering in oxide TFTs, offering a promising platform for future high-performance, flexible, and large-area electronic systems.