Effective threshold voltage modulation technique for steep-slope 2D atomic threshold switching field-effect transistor

Abstract

Two-dimensional (2D) atomic threshold switching field-effect transistors (ATS-FETs), which integrate 2D FET with threshold switching (TS) devices, have garnered attention as part of the subthreshold swing (SS) improvement for next-generation low-power devices. For industrial applications of 2D ATS-FET, it is important to secure the threshold voltage (V-th) modulation technique. Here, V-th engineering is performed by altering the counter electrode (CE) of a TS device, and the electrical performance of the ATSFET is systematically investigated. The work function difference between the active electrode and CE alters the internal electric field (E-field) formed between these two electrodes. This severely affects the metal ion migration of the active electrode and induces the V-th shift of the ATS-FET. Because the proposed V-th adjusting technique does not affect the channel material, the MoS2 ATS-FET with the proposed technique can shift V-th while maintaining a high on-off ratio of >10(5) A on average and achieves an ultralow average SS of similar to 10.929 mV/dec. Moreover, the SS variation due to the random interface traps between the channel and gate dielectric is sufficiently suppressed. This study is expected to be a cornerstone for ATS-FET research by offering a compact platform to adjust Vth without deteriorating steep-slope characteristics. (c) 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).