Dramatic Reduction of Contact Resistance via Ultrathin LiF in Two-Dimensional MoS<sub>2</sub> Field Effect Transistors.

Cho, Hyunmin; Kang, Donghee; Lee, Yangjin; Bae, Heesun; Hong, Sungjae; Cho, Yongjae; Kim, Kwanpyo; Yi, Yeonjin et al. · Nano Lett · 2021

basic_science · Level V

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Abstract

Molybdenum disulfide (MoS<sub>2</sub>) has been regarded as one of the most important n-type two-dimensional (2D) transition metal dichalcogenide semiconductors for nanoscale electron devices. Relatively high contact resistance (<i>R</i><sub>C</sub>) remains as an issue in the 2D-devices yet to be resolved. Reliable technique is very compelling to practically produce low <i>R</i><sub>C</sub> values in device electronics, although scientific approaches have been made to obtain a record-low <i>R</i><sub>C</sub>. To resolve this practical issue, we here use thermal-evaporated ultrathin LiF between channel and source/drain metal to fabricate 2D-like MoS<sub>2</sub> field effect transistors (FETs) with minimum <i>R</i><sub>C</sub>. Under 4-bar FET method, <i>R</i><sub>C</sub> less than ∼600 Ω·μm is achieved from the LiF/Au contact MoS<sub>2</sub> FET. Our normal 2-bar FET with LiF thus shows the same mobility as that of 4-bar FET that should have no <i>R</i><sub>C</sub> in principle. On the basis of these results, ultrathin LiF is also applied for transparent conducting oxide contact, successfully enabling transparent MoS<sub>2</sub> FETs.