Surface passivation engineering approach to fluoroacrylate-incorporated polytetrafluoroethylene for highly reliable a-IGZO TFTs

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2022-06, Vol.1 (23), p.9114-9123
• Main Authors: Shan, Fei, Zhao, Han-Lin, Wang, Xiao-Lin, Lee, Jae-Yun, Kim, Sung-Jin
• Format: Article
• Language: English
• Subjects: Electronics; Gallium; Hydrophobicity; Indium gallium zinc oxide; Inorganic materials; Leakage current; Low level; Organic materials; Passivity; Polytetrafluoroethylene; Semiconductor devices; Stability tests; Surface energy; Thin film transistors; Wearable technology; Zinc oxide
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/d2tc01053d

Amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs) have attracted considerable attention for cutting-edge and next-generation electronics applications because of their high field-effect mobility, low leakage current, superior uniformity, and high transparency. On the other hand, maintaining stable electrical performance under the influence of various ambient and complex operating environments is a serious application problem. Hence, a fluoroacrylate-incorporated polytetrafluoroethylene (F-P) is proposed as a new material for passivation layers (PVLs) of a-IGZO TFTs. Solution process-based F-P PVLs were introduced to overcome the intrinsically brittle nature of inorganic materials and enhance the long-term stability of organic materials because of their excellent flexibility, hydrophobicity, and chemical stability. This also provides a simple and cheaper alternative for practical applications. The F-P PVLs with different concentrations exhibited appropriate improvements in stability and electrical performance. Of these, the 1.0 wt% F-P passivated IGZO TFTs showed improved performance in saturation mobility ( μ sat ) from 6.23 ± 0.21 to 7.02 ± 0.38 cm −2 V −1 s −1 , an on-off current ratio ( I on / I off ) from (4.05 ± 0.84) × 10 5 to (3.75 ± 2.32) × 10 8 , and a subthreshold swing (SS) from 1.79 ± 0.30 to 0.41 ± 0.04 V per decade compared to the pristine device without the F-P PVL. After the 15 day stability test under ambient conditions, μ sat increased from 7.02 ± 0.38 to ∼8 cm 2 V −1 s −1 ; I on / I off increased from (3.75 ± 2.32) × 10 8 to ∼10 10 and the SS values were maintained at a low level (≤0.6 V dec −1 ). The improvement was induced by lower surface energy and better hydrophobicity from F-P PVLs, which can effectively reduce the adsorption behavior of H 2 O and O 2 . With a lower oxygen-related interface trap density, the electrical performances were improved by a suitable concentration-based F-P PVL. In addition, the F-P PVL can provide a long-term guarantee of stability and reliability for a-IGZO TFTs, which will have potential applications for wearable devices and multi-environment electronics devices. A fluoroacrylate-incorporated polytetrafluoroethylene as a new material for passivation layers of a-IGZO TFTs is a potential technology to enhance stability by reducing the adsorption behavior of H 2 O and O 2 .