Chip-Scale Graphene/IGZO Cold Source FET Array Enabling Sub-60 mV dec<sup>-1</sup> Super-Steep Subthreshold Swing.

Oh, Seyoung; Kwon, Ojun; Yoon, Jongwon; Cho, Eunjeong; Kim, Min Jeong; Seo, Wondeok; Kim, Minhee; Kim, Shinhoi et al. · Adv Mater · 2026

basic_science · Level V

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Abstract

In this study, the first sub-60 mV dec<sup>-1</sup> super-steep subthreshold swing (SS) of graphene/InGaZnO (IGZO) cold-source field-effect transistor (CSFET) arrays is demonstrated. The linear density of states of the Dirac-cone-type graphene suppresses the Boltzmann thermal tail near the graphene/IGZO interface which in turn causes super-exponentially decaying electron density with increasing energy, leading to an extremely low off current and SS value. In particular, by introducing an HfO<sub>2</sub> high-k dielectric with a low body factor, the surface potential is effectively modulated, further reducing SS by ≈46.4 mV dec<sup>-1</sup>. Furthermore, highly uniform sub-60 mV dec<sup>-1</sup> SS with a yield of ≈89.1% is achieved in the IGZO CSFET 8 × 8 array devices, with a record SS value of 23.66 mV dec<sup>-1</sup> compared to previously reported oxide-semiconductor transistors. The proposed IGZO CSFET device is expected to drive significant advancements in high-speed and ultralow-power electronic circuits.