Low-temperature fabrication of an HfO2 passivation layer for amorphous indium-gallium-zinc oxide thin film transistors using a solution process

Seonghwan Hong; Sung Pyo Park; Yeong-Gyu Kim; Byung Ha Kang; Jae Won Na; Hyun Jae Kim

doi:10.1038/s41598-017-16585-x

Low-temperature fabrication of an HfO₂ passivation layer for amorphous indium-gallium-zinc oxide thin film transistors using a solution process

Sci Rep. 2017 Nov 24;7(1):16265. doi: 10.1038/s41598-017-16585-x.

Authors

Seonghwan Hong¹, Sung Pyo Park¹, Yeong-Gyu Kim¹, Byung Ha Kang¹, Jae Won Na¹, Hyun Jae Kim²

Affiliations

¹ School of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea.
² School of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea. hjk3@yonsei.ac.kr.

Abstract

We report low-temperature solution processing of hafnium oxide (HfO₂) passivation layers for amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs). At 150 °C, the hafnium chloride (HfCl₄) precursor readily hydrolyzed in deionized (DI) water and transformed into an HfO₂ film. The fabricated HfO₂ passivation layer prevented any interaction between the back surface of an a-IGZO TFT and ambient gas. Moreover, diffused Hf⁴⁺ in the back-channel layer of the a-IGZO TFT reduced the oxygen vacancy, which is the origin of the electrical instability in a-IGZO TFTs. Consequently, the a-IGZO TFT with the HfO₂ passivation layer exhibited improved stability, showing a decrease in the threshold voltage shift from 4.83 to 1.68 V under a positive bias stress test conducted over 10,000 s.

Publication types

Research Support, Non-U.S. Gov't