Optoelectronic properties of valence-state-controlled amorphous niobium oxide

Takaki Onozato, Takayoshi Katase, Akira Yamamoto, Shota Katayama, Koichi Matsushima, Naho Itagaki, Hisao Yoshida, Hiromichi Ohta

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


In order to understand the optoelectronic properties of amorphous niobium oxide (a-NbOx), we have investigated the valence states, local structures, electrical resistivity, and optical absorption of a-NbOx thin films with various oxygen contents. It was found that the valence states of Nb ion in a-NbOx films can be controlled from 5+ to 4+ by reducing oxygen pressure during film deposition at room temperature, together with changing the oxide-ion arrangement around Nb ion from Nb2O5-like to NbO2-like local structure. As a result, a four orders of magnitude reduction in the electrical resistivity of a-NbOx films was observed with decreasing oxygen content, due to the carrier generation caused by the appearance and increase of an oxygen-vacancy-related subgap state working as an electron donor. The tunable optoelectronic properties of a-NbOx films by valence-state-control with oxygen-vacancy formation will be useful for potential flexible optoelectronic device applications.

Original languageEnglish
Article number255001
JournalJournal of Physics Condensed Matter
Issue number25
Publication statusPublished - May 10 2016

All Science Journal Classification (ASJC) codes

  • General Materials Science
  • Condensed Matter Physics


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