TY - JOUR
T1 - Optoelectronic properties of valence-state-controlled amorphous niobium oxide
AU - Onozato, Takaki
AU - Katase, Takayoshi
AU - Yamamoto, Akira
AU - Katayama, Shota
AU - Matsushima, Koichi
AU - Itagaki, Naho
AU - Yoshida, Hisao
AU - Ohta, Hiromichi
N1 - Funding Information:
The authors would like to thank Profs H Hosono, H Hiramatsu, and K Ide for optical measurements, and N Kawai for experimental help on TEM/STEM analyses. The optical measurements were supported by the Collaborative Research Project of the Materials and Structures Laboratory, Tokyo Institute of Technology. The TEM/STEM analyses, conducted at Hokkaido University, were supported by the Nanotechnology Platform Program from MEXT. The Nb-K edge XAFS experiments were performed under the approval of the Photon Factory Program Advisory Committee (Proposal No. 2014G547). This work was supported by Grant-in-Aid for Scientific Research on Innovative Areas (25106007), Grant-in-Aid for Scientific Research A (25246023) from JSPS and the Network Joint Research Center for Materials and Devices. TK was supported by Grant-in-Aid for Young Scientists A (15H05543) and Grant-in-Aid for Challenging Exploratory Research (16K14377) from JSPS.
Publisher Copyright:
© 2016 IOP Publishing Ltd.
PY - 2016/5/10
Y1 - 2016/5/10
N2 - 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.
AB - 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.
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U2 - 10.1088/0953-8984/28/25/255001
DO - 10.1088/0953-8984/28/25/255001
M3 - Article
AN - SCOPUS:84969667354
SN - 0953-8984
VL - 28
JO - Journal of Physics Condensed Matter
JF - Journal of Physics Condensed Matter
IS - 25
M1 - 255001
ER -