Barrier‐Assisted Plasma Doping for Spatially Selective Resistance Engineering in MoS ₂ Transistors

ABSTRACT

Atomically thin transition‐metal dichalcogenides (TMDs) are promising channel materials for low‐power logic. However, the absence of scalable and region‐selective doping techniques leads to excessive local resistances that hinder the technological readiness of 2D transistors. Here, a barrier‐assisted NH ₃ plasma process is demonstrated that enables degenerate n‐type doping of monolayer MoS ₂ while preserving its crystallinity. The ultrathin pV3D3/Al ₂ O ₃ dielectric stack not only blocks plasma‐induced damage but also functions as a chemical filter that permits NH _x radicals to diffuse through. Through this doping process, an electron density of 4.3 × 10 ¹³ cm ⁻² is achieved, yielding a contact resistance of 1.45 kΩ·µm. Density functional calculations show that NH ₂ radicals adsorbed on the pristine MoS ₂ surface are the main source of n‐type doping while NH radicals can heal S‐vacancy defects. Leveraging the spatial selectivity of this approach, mobility and on‐current are enhanced by 5.8‐fold with negligible threshold‐voltage shift. Extension‐region activation further suppresses series resistance, increasing the on‐current by 260‐fold ( V _DS = 0.05 V) while maintaining enhancement‐mode operation. These findings establish barrier‐assisted NH ₃ plasma doping as a promising approach for enabling high‐performance n‐type 2D transistors and advancing future energy‐efficient 2D CMOS technology.