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<p>In this article, we present a first-principles field-effect transistors (FETs) contact study based on density functional theory and the non-equilibrium Green’s function method. We estimate device performance for three transition-metal-dichalcogenide (TMD) channel materials (WSe<sub>2</sub>, WS<sub>2</sub>, and MoS<sub>2</sub>), including metal contacts (Ni) at source and drain for the first time. The results show that the variation in <i>R</i><sub><i>c</i></sub> has less impact on <i>I</i><sub><i>ON</i></sub> and <i>I</i><sub><i>OFF</i></sub> at a given V<sub>DD</sub> than the variation in subthreshold swing (<i>SS</i>; with differences exceeding 30 mV/dec), suggesting <i>SS</i> may be more sensitive to the contacting material choice than previously realized at gate lengths below 15 nm. Among the channel and contact material combinations studied, Ni/WSe<sub>2</sub> FET leads to the best short-channel device performance. The quantum transport calculation shows the highest density of charge accumulation at the Ni/WSe<sub>2</sub> contact edge. Inspired by this first-principles study, we performed X-ray photoelectron spectroscopy and verified the bonding strength at the Ni/WSe<sub>2</sub> contact to be stronger than Ni/WS<sub>2</sub> and Ni/MoS<sub>2</sub> contacts. This supports the theoretical finding that the contact/channel materials need to be chosen to optimize <i>SS</i> and <i>I</i><sub><i>ON</i></sub> in short-channel TMD FETs.</p>

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Investigating contact-limited scaling in sub-15-nm TMD FETs from first-principles

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年1月10日

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  • Kuan-Bo Lin,
  • Hui-Ting Liu,
  • Shin-Yuan Wang,
  • Shu-Jui Chang,
  • Chao-Cheng Kaun,
  • Chenming Hu

摘要

In this article, we present a first-principles field-effect transistors (FETs) contact study based on density functional theory and the non-equilibrium Green’s function method. We estimate device performance for three transition-metal-dichalcogenide (TMD) channel materials (WSe2, WS2, and MoS2), including metal contacts (Ni) at source and drain for the first time. The results show that the variation in Rc has less impact on ION and IOFF at a given VDD than the variation in subthreshold swing (SS; with differences exceeding 30 mV/dec), suggesting SS may be more sensitive to the contacting material choice than previously realized at gate lengths below 15 nm. Among the channel and contact material combinations studied, Ni/WSe2 FET leads to the best short-channel device performance. The quantum transport calculation shows the highest density of charge accumulation at the Ni/WSe2 contact edge. Inspired by this first-principles study, we performed X-ray photoelectron spectroscopy and verified the bonding strength at the Ni/WSe2 contact to be stronger than Ni/WS2 and Ni/MoS2 contacts. This supports the theoretical finding that the contact/channel materials need to be chosen to optimize SS and ION in short-channel TMD FETs.