Self‐Aligned Spacer Doping in MoS ₂ High‐κ Top‐Gate Transistors

ABSTRACT Because 2D materials are atomically thin and free of dangling bonds, integrating high‐κ dielectrics and achieving spacer doping remain challenging using traditional atomic layer deposition (ALD) techniques and ion implantation method. Here, a “high‐κ top‐gate lift‐off” strategy enabling the precise fabrication of underlap MoS 2 field‐effect transistors (FETs) with well‐defined spacer regions is presented. A high‐κ Erbium oxide (ErO x ) dielectric, deposited by reactive thermal evaporation, provides a dielectric constant of 14.4 and smooth coverage on transition‐metal dichalcogenides (TMDs). The process further incorporates a self‐aligned covalently functionalized n ‐doping method to ensure effective contact and spacer doping, achieving uniform carrier concentration and reduced contact resistance. The resulting spacer‐doped top‐gate MoS 2 device exhibits an on‐current enhancement of 180‐fold while maintaining an on/off ratio of nearly 10 8 under single top‐gate operation. Remarkably, the single‐gate configuration outperforms undoped dual‐gate devices in both current level and switching characteristics. This study establishes a scalable and reliable platform for integrating high‐κ dielectrics with self‐aligned doping, paving the way for next‐generation high‐performance 2D electronics.