Effect of Hydrogen Migration in SiO2/Al2O3 Stacked Gate Insulator of InGaZnO Thin-Film Transistors

• Published in: Crystals (Basel) Vol. 12; no. 5; p. 594
• Main Authors: Park, Shinyoung, Youn, Sangwook, Jang, Jun Tae, Kim, Hyungjin, Kim, Dae Hwan
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 23.04.2022
• Subjects: Aluminum oxide; Bias; Deposition; Hydrogen; Indium gallium zinc oxide; InGaZnO thin-film transistor; Insulators; low-temperature atomic layer deposition; Optimization; Polyethylene terephthalate; Semiconductor devices; Silicon dioxide; synaptic device; Thin film transistors; Threshold voltage; Transistors; X ray photoelectron spectroscopy; XPS
• ISSN: 2073-4352; 2073-4352
• DOI: 10.3390/cryst12050594

In this work, the correlation between SiO2 deposition thickness and hydrogen content is discussed and the effect of the SiO2 layer on the properties of synaptic InGaZnO (IGZO) TFTs is analyzed. Three types of IGZO synaptic thin-film transistors (TFTs) were fabricated with different gate insulators, and the effect of SiO2 as a gate insulator was investigated. XPS analysis confirmed that the hydrogen content in the Al2O3 and SiO2 layers increased during SiO2 deposition step for all depth regions. Hydrogen injected by the SiO2 layer deposition step was confirmed to improve the memory window through more threshold voltage shift under positive bias stress (PBS) and negative bias stress (NBS) conditions. In addition, the retention characteristics were improved due to the low hydrogen movement velocity in the SiO2 layer. These results contribute to the optimization of the amount of hydrogen, and the proposed device has potential as a synaptic device capable of neuromorphic computing.