Charge compensation by excess oxygen in amorphous In-Ga-Zn-O films deposited by pulsed laser deposition

Takatoshi Orui, Johannes Herms, Yuichiro Hanyu, Shigenori Ueda, Ken Watanabe, Isao Sakaguchi, Naoki Ohashi, Hidenori Hiramatsu, Hideya Kumomi, Hideo Hosono, Toshio Kamiya

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)

Abstract

We investigated effects of base pressure (Pbase) of the deposition chamber on electrical properties and defect states of amorphous In-Ga-Zn-O (a-IGZO) thin films deposited by pulsed laser deposition. The impurity hydrogen concentration was increased by an order of magnitude when Pbase was deteriorated from <10-5 to 10-3Pa. The optimum oxygen partial pressures (PO2) were 2-4 Pa for an optimized deposition condition with the good Pbase; on the other hand, off-optimized and/or poor Pbase require much higher PO2. This result provides an experimental evidence for a charge compensation model by excess oxygen for H-containing a-IGZO. Thermal desorption spectra indicated that the impurity hydrogens originate mainly from water molecules in the residual gas and exist as -OH chemical bonding states in the a-IGZO films. Hard X-ray photoemission spectroscopy revealed that these -OH states form deep defects above the valence band maximum.

Original languageEnglish
Article number6898819
Pages (from-to)518-522
Number of pages5
JournalIEEE/OSA Journal of Display Technology
Volume11
Issue number6
DOIs
Publication statusPublished - Jun 1 2015
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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