Partially Oxidized TaS<sub>2</sub> as a High-Quality Gate Stack for Two-Dimensional Transistors.

Guan, Kejie; Dai, Hao; Sun, Fuqin; Gou, Xiaoshuang; Liu, Lin; Wang, Yingyi; Zhou, Weifan; Xia, Yang et al. · Nano Lett · 2025

basic_science · Level V

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Abstract

Two-dimensional (2D) semiconductors are promising channel materials for next-generation transistors, but the integration of gate stacks with clean interfaces remains challenging. Here, we demonstrate that a high-quality gate stack, composed of a van der Waals gate metal and high-κ dielectric, could be prepared via partial oxidation of layered tantalum disulfide (TaS<sub>2</sub>), and integrated with 2D semiconductors through van der Waals assembly. This nondestructive and contamination-free process ensured atomically abrupt and impurity-free interfaces of the gate-electrode/dielectric and dielectric/semiconductor. The chemically converted TaO<sub><i>x</i></sub> displayed dielectric properties with a high dielectric constant of 28.6 and a breakdown field of 5 MV/cm. Top-gated 2D MoS<sub>2</sub> FETs fabricated using the obtained TaO<sub><i>x</i></sub>/TaS<sub>2</sub> heterostructure as gate stack exhibited an on/off current ratio over 10<sup>7</sup>, a subthreshold swing down to 61.7 mV/decade and a gate leakage current below 50 fA. We also show that the TaO<sub><i>x</i></sub>/TaS<sub>2</sub> gate stack could be used to construct high-gain (>90) 2D complementary inverters.