Correlation between active layer thickness and ambient gas stability in IGZO thin-film transistors

Xu Gao, Meng Fang Lin, Bao Hua Mao, Maki Shimizu, Nobuhiko Mitoma, Takio Kizu, Wei Ou-Yang, Toshihide Nabatame, Zhi Liu, Kazuhito Tsukagoshi, Sui Dong Wang

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

Decreasing the active layer thickness has been recently reported as an alternative way to achieve fully depleted oxide thin-film transistors for the realization of low-voltage operations. However, the correlation between the active layer thickness and device resistivity to environmental changes is still unclear, which is important for the optimized design of oxide thin-film transistors. In this work, the ambient gas stability of IGZO thin-film transistors is found to be strongly correlated to the IGZO thickness. The TFT with the thinnest IGZO layer shows the highest intrinsic electron mobility in a vacuum, which is greatly reduced after exposure to O2/air. The device with a thick IGZO layer shows similar electron mobility in O2/air, whereas the mobility variation measured in the vacuum is absent. The thickness dependent ambient gas stability is attributed to a high-mobility region in the IGZO surface vicinity with less sputtering-induced damage, which will become electron depleted in O2/air due to the electron transfer to adsorbed gas molecules. The O2 adsorption and deduced IGZO surface band bending is demonstrated by the ambient-pressure x-ray photoemission spectroscopy results.

Original languageEnglish
Article number025102
JournalJournal of Physics D: Applied Physics
Volume50
Issue number2
DOIs
Publication statusPublished - 2017 Jan 18
Externally publishedYes

Keywords

  • APXPS
  • IGZO
  • ambient gas stability
  • thin-film transistors

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Acoustics and Ultrasonics
  • Surfaces, Coatings and Films

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