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Updated: Mar 21, 2026

Niobium Oxide Films Deposited by Reactive Sputtering: Effect of Oxygen Flow Rate
Published on: September 28, 2019
Optoelectronic properties of valence-state-controlled amorphous niobium oxide
Takaki Onozato1, Takayoshi Katase2, Akira Yamamoto3,4
1Graduate School of Information Science and Technology, Hokkaido University, N14W19, Kita, Sapporo 060-0814, Japan.
None:
In order to understand the optoelectronic properties of amorphous niobium oxide (a-NbO x ), we have investigated the valence states, local structures, electrical resistivity, and optical absorption of a-NbO x thin films with various oxygen contents. It was found that the valence states of Nb ion in a-NbO x 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-NbO x 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-NbO x films by valence-state-control with oxygen-vacancy formation will be useful for potential flexible optoelectronic device applications.
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