Amorphous gallium oxide as an improved host for inorganic light-emitting thin film semiconductor fabricated at room temperature on glass

Naoto Watanabe, Junghwan Kim, Keisuke Ide, Hidenori Hiramatsu, Hiroshi Kumigashira, Shigenori Ueda, Hideo Hosono, Toshio Kamiya

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

We report new amorphous oxide semiconductor (AOS)-based thin film phosphor, Eu-doped α-Ga2Ox (α-GO:Eu), to solve the issues of previously reported α-In-Ga-Zn-O:Eu (α-IGZO:Eu). The internal quantum efficiencies (IQE) of α-GO:Eu (2.3% for unannealed, 8.3% for annealed films) are improved from those of α-IGZO:Eu (0.9% and 1.6%, respectively) because of the much wider bandgap (4.26 eV), subsequent low residual electron density, and higher available annealing temperature. We found that the annealing temperature to improve IQE is limited by crystallization temperature. Another issue of α-IGZO:Eu is that the initial state of Eu3+ 4f is deeper than the valence band maximum (VBM), which is not suitable for light-emitting diode. We expected that Eu3+ 4f would locate above the VBM in α-GO:Eu because the VBM of α-Ga2Ox is ∼0.8 eV deeper than that of α-IGZO. However, resonant photoemission spectroscopy revealed that the Eu 4f states are bound more to the O 2p valence band than to the vacuum level, and the Eu3+ 4f states in α-GO:Eu are still buried in the valence band.

Original languageEnglish
Pages (from-to)P410-P414
JournalECS Journal of Solid State Science and Technology
Volume6
Issue number7
DOIs
Publication statusPublished - 2017 Jan 1
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials

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