In Situ Engineering of Vertical Indium Gradients via Sputtering Kinetics for High-Performance IGZO Channel-All-Around Transistors.

Sun, Jiabao; Yu, Wei; Zhang, Jing; Jin, Meichen; Liu, Chang; Sun, Xianglie; Yang, Fuwang; Wei, Tiantian et al. · Nano Lett · 2026

basic_science · Level V

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Abstract

Vertical channel-all-around (VCAA) transistors based on indium-gallium-zinc oxide (IGZO) are promising candidates for monolithic 3D integration. However, they inherently suffer from contact resistance asymmetry and trade-offs between the drive-current and leakage due to uniform channel doping limitations. This study demonstrates a high-performance VCAA FET featuring a vertical indium-gradient channel, engineered via in situ resputtering kinetics during deposition. The modulated band structure reduces the Schottky barrier height (ϕ<sub>BN</sub>) at the bottom electrode, achieving a record high on-current of 82.8 μA/μm and an ultralow contact resistivity of 8 × 10<sup>-7</sup> Ω·cm<sup>2</sup>. We propose an analytical framework to decouple top and bottom contact resistances, revealing that transport behavior is driven by asymmetric ϕ<sub>BN</sub> and drain-induced barrier thinning (DIBT). This work provides fundamental insights into vertical transport in oxide semiconductors and offers a scalable pathway for engineering contact symmetry in vertical logic devices.