Static and Dynamic Water Motion-Induced Instability in Oxide Thin-Film Transistors and Its Suppression by Using Low-k Fluoropolymer Passivation

Seungbeom Choi; Jeong-Wan Jo; Jaeyoung Kim; Seungho Song; Jaekyun Kim; Sung Kyu Park; Yong-Hoon Kim

doi:10.1021/acsami.7b05948

Static and Dynamic Water Motion-Induced Instability in Oxide Thin-Film Transistors and Its Suppression by Using Low-k Fluoropolymer Passivation

ACS Appl Mater Interfaces. 2017 Aug 9;9(31):26161-26168. doi: 10.1021/acsami.7b05948. Epub 2017 Jul 31.

Authors

Seungbeom Choi, Jeong-Wan Jo¹, Jaeyoung Kim, Seungho Song, Jaekyun Kim², Sung Kyu Park¹, Yong-Hoon Kim

Affiliations

¹ School of Electrical and Electronic Engineering, Chung-Ang University , Seoul 06980, Korea.
² Department of Photonics and Nanoelectronics, Hanyang University , Ansan 15588, Korea.

PMID: 28730810
DOI: 10.1021/acsami.7b05948

Abstract

Here, we report static and dynamic water motion-induced instability in indium-gallium-zinc-oxide (IGZO) thin-film transistors (TFTs) and its effective suppression with the use of a simple, solution-processed low-k (ε ∼ 1.9) fluoroplastic resin (FPR) passivation layer. The liquid-contact electrification effect, in which an undesirable drain current modulation is induced by a dynamic motion of a charged liquid such as water, can cause a significant instability in IGZO TFTs. It was found that by adopting a thin (∼44 nm) FPR passivation layer for IGZO TFTs, the current modulation induced by the water-contact electrification was greatly reduced in both off- and on-states of the device. In addition, the FPR-passivated IGZO TFTs exhibited an excellent stability to static water exposure (a threshold voltage shift of +0.8 V upon 3600 s of water soaking), which is attributed to the hydrophobicity of the FPR passivation layer. Here, we discuss the origin of the current instability caused by the liquid-contact electrification as well as various static and dynamic stability tests for IGZO TFTs. On the basis of our findings, we believe that the use of a thin, solution-processed FPR passivation layer is effective in suppressing the static and dynamic water motion-induced instabilities, which may enable the realization of high-performance and environment-stable oxide TFTs for emerging wearable and skin-like electronics.

Keywords: fluoropolymer passivation; indium−gallium−zinc oxide; liquid-contact-electrification; solution process; thin-film transistors; water stability.