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

• Published in: Scientific reports Vol. 7; no. 1; pp. 1 - 9
• Main Authors: Hong, Seonghwan, Park, Sung Pyo, Kim, Yeong-gyu, Kang, Byung Ha, Kim, Hyun Jae
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group 24.11.2017; Nature Publishing Group UK
• Subjects: Gallium; Transistors; Zinc oxide; Zinc oxides
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-017-16585-x

Abstract We report low-temperature solution processing of hafnium oxide (HfO 2 ) passivation layers for amorphous indium–gallium–zinc oxide (a-IGZO) thin-film transistors (TFTs). At 150 °C, the hafnium chloride (HfCl 4 ) precursor readily hydrolyzed in deionized (DI) water and transformed into an HfO 2 film. The fabricated HfO 2 passivation layer prevented any interaction between the back surface of an a-IGZO TFT and ambient gas. Moreover, diffused Hf 4+ 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 HfO 2 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.