Breaking the SS- I on trade-off in 2D TFETs through an isolated conduction band in monolayer AgSe

Tunneling field-effect transistors (TFETs), operating through the band-to-band tunneling (BTBT) mechanism, are widely regarded as strong contenders for future low-power (LP) electronic applications on account of the potential to achieve subthreshold swings (SS) below 60 mV∙dec −1 . Nevertheless, the inherently limited on-state current ( I on ) has consistently posed a significant challenge. Here, we demonstrate that a two-dimensional monolayer AgSe TFET can obtain a sub-60 mV∙dec −1 SS and a high on-current at the same time without complex source engineering strategies. The unique isolated conduction band of monolayer AgSe produces a sharp band edge, significantly enhancing the BTBT efficiency and facilitates steep switching characteristics. For a 10 nm p -type AgSe TFET, an SS as low as 31 mV∙dec −1 is obtained, with on-currents reaching 1617 and 716 μ A∙ μ m −1 for high-performance and LP applications, satisfying the requirements defined by the International Technology Roadmap for Semiconductors. Even if the supply voltage ( V dd ) drops to 0.5 V, the 5 nm device maintains an SS min = 43 mV∙dec −1 , demonstrating excellent voltage scalability. Benchmark comparisons with other widely studied 2D materials further confirm the superior performance of AgSe TFETs. These results identify monolayer AgSe as a highly promising channel material and suggest that isolated-band engineering provides an effective design paradigm for next-generation LP nanoelectronic devices.