Large and constant absorption coefficient in Nb                         x                         Ti                         1−                                                                              x                         O                         2                          thin films throughout the visible range

Adam E. Shimabukuro; Akihiro Ishii; Itaru Oikawa; Yusuke Yamazaki; Masaaki Imura; Toshimasa Kanai; Fumio S. Ohuchi; Hitoshi Takamura

doi:10.1016/j.apsusc.2018.09.036

Large and constant absorption coefficient in Nb _x Ti ₁₋ _x O ₂ thin films throughout the visible range

Adam E. Shimabukuro, Akihiro Ishii, Itaru Oikawa, Yusuke Yamazaki, Masaaki Imura, Toshimasa Kanai, Fumio S. Ohuchi, Hitoshi Takamura

Research output: Contribution to journal › Article › peer-review

5 Citations (Scopus)

Abstract

We investigated the optical absorption properties of Nb _x Ti _1−x O ₂ thin films, a solid solution combining the reduced titanium and niobium oxide phases TiO ₂ and NbO _2. The optical absorption properties of Nb _x Ti _1−x O ₂ thin films prepared by pulsed laser deposition at 600 °C were shown to be large in magnitude at an almost constant value of ≈17 µm ⁻¹ . Because this large absorption coefficient is nearly independent of incident photon energy in the visible range (400–700 nm), the Nb _x Ti _1−x O ₂ thin films appear optically black. Flat and homogenous, optically black coatings like these are desirable for color isolation in flat panel displays. The origin of flat wavelength dispersion in Nb _x Ti _1−x O ₂ is the coexistence of semiconducting absorption and metallic light absorption mechanisms. Localized Nb-Nb dimers in the metallic Nb _x Ti _1−x O ₂ phase open an optical band gap which gives rise to semiconducting behavior. We show here that reduction results in strong visible light sensitization in normally transparent Nb-Ti oxides.

Original language	English
Pages (from-to)	61-67
Number of pages	7
Journal	Applied Surface Science
Volume	464
DOIs	https://doi.org/10.1016/j.apsusc.2018.09.036
Publication status	Published - 2019 Jan 15

Keywords

Absorption coefficient
NbO
Non-dispersive media
Pulsed laser deposition
Ti O

ASJC Scopus subject areas

Chemistry(all)
Condensed Matter Physics
Physics and Astronomy(all)
Surfaces and Interfaces
Surfaces, Coatings and Films

Access to Document

10.1016/j.apsusc.2018.09.036

Cite this

Shimabukuro, A. E., Ishii, A., Oikawa, I., Yamazaki, Y., Imura, M., Kanai, T., Ohuchi, F. S., & Takamura, H. (2019). Large and constant absorption coefficient in Nb _x Ti ₁₋ _x O ₂ thin films throughout the visible range Applied Surface Science, 464, 61-67. https://doi.org/10.1016/j.apsusc.2018.09.036

Large and constant absorption coefficient in Nb _x Ti ₁₋ _x O ₂ thin films throughout the visible range . / Shimabukuro, Adam E.; Ishii, Akihiro ; Oikawa, Itaru; Yamazaki, Yusuke; Imura, Masaaki; Kanai, Toshimasa; Ohuchi, Fumio S.; Takamura, Hitoshi.

In: Applied Surface Science, Vol. 464, 15.01.2019, p. 61-67.

Research output: Contribution to journal › Article › peer-review

Shimabukuro, AE, Ishii, A , Oikawa, I, Yamazaki, Y, Imura, M, Kanai, T, Ohuchi, FS & Takamura, H 2019, ' Large and constant absorption coefficient in Nb _x Ti ₁₋ _x O ₂ thin films throughout the visible range ', Applied Surface Science, vol. 464, pp. 61-67. https://doi.org/10.1016/j.apsusc.2018.09.036

Shimabukuro AE, Ishii A , Oikawa I, Yamazaki Y, Imura M, Kanai T et al. Large and constant absorption coefficient in Nb _x Ti ₁₋ _x O ₂ thin films throughout the visible range Applied Surface Science. 2019 Jan 15;464:61-67. https://doi.org/10.1016/j.apsusc.2018.09.036

Shimabukuro, Adam E. ; Ishii, Akihiro ; Oikawa, Itaru ; Yamazaki, Yusuke ; Imura, Masaaki ; Kanai, Toshimasa ; Ohuchi, Fumio S. ; Takamura, Hitoshi. / Large and constant absorption coefficient in Nb _x Ti ₁₋ _x O ₂ thin films throughout the visible range In: Applied Surface Science. 2019 ; Vol. 464. pp. 61-67.

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title = " Large and constant absorption coefficient in Nb x Ti 1− x O 2 thin films throughout the visible range ",

abstract = " We investigated the optical absorption properties of Nb x Ti 1−x O 2 thin films, a solid solution combining the reduced titanium and niobium oxide phases TiO 2 and NbO 2. The optical absorption properties of Nb x Ti 1−x O 2 thin films prepared by pulsed laser deposition at 600 °C were shown to be large in magnitude at an almost constant value of ≈17 µm −1 . Because this large absorption coefficient is nearly independent of incident photon energy in the visible range (400–700 nm), the Nb x Ti 1−x O 2 thin films appear optically black. Flat and homogenous, optically black coatings like these are desirable for color isolation in flat panel displays. The origin of flat wavelength dispersion in Nb x Ti 1−x O 2 is the coexistence of semiconducting absorption and metallic light absorption mechanisms. Localized Nb-Nb dimers in the metallic Nb x Ti 1−x O 2 phase open an optical band gap which gives rise to semiconducting behavior. We show here that reduction results in strong visible light sensitization in normally transparent Nb-Ti oxides. ",

keywords = "Absorption coefficient, NbO, Non-dispersive media, Pulsed laser deposition, Ti O",

author = "Shimabukuro, {Adam E.} and Akihiro Ishii and Itaru Oikawa and Yusuke Yamazaki and Masaaki Imura and Toshimasa Kanai and Ohuchi, {Fumio S.} and Hitoshi Takamura",

note = "Funding Information: This work has been financially supported in part by JSPS KAKENHI grant number 18H03832 . AS would like to thank the research placement done by Junior Year Programs in English (JYPE) at Tohoku University. AI would like to express his appreciation for the financial from the Grant-in-Aid for JSPS Research Fellows and the Interdepartmental Doctoral Degree Program for Multi-dimensional Materials Science Leaders in Tohoku University. The authors would like to acknowledge the vitally important encouragement and support made through the University of Washington-Tohoku University: Academic Open Space (UW-TU:AOS). They also would like to thank Ms. Y. Ohira and Mr. N. Akao for technical support in taking XPS measurements. Publisher Copyright: {\textcopyright} 2018 Elsevier B.V.",

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AU - Shimabukuro, Adam E.

AU - Ishii, Akihiro

AU - Oikawa, Itaru

AU - Yamazaki, Yusuke

AU - Imura, Masaaki

AU - Kanai, Toshimasa

AU - Ohuchi, Fumio S.

AU - Takamura, Hitoshi

N1 - Funding Information: This work has been financially supported in part by JSPS KAKENHI grant number 18H03832 . AS would like to thank the research placement done by Junior Year Programs in English (JYPE) at Tohoku University. AI would like to express his appreciation for the financial from the Grant-in-Aid for JSPS Research Fellows and the Interdepartmental Doctoral Degree Program for Multi-dimensional Materials Science Leaders in Tohoku University. The authors would like to acknowledge the vitally important encouragement and support made through the University of Washington-Tohoku University: Academic Open Space (UW-TU:AOS). They also would like to thank Ms. Y. Ohira and Mr. N. Akao for technical support in taking XPS measurements. Publisher Copyright: © 2018 Elsevier B.V.

PY - 2019/1/15

Y1 - 2019/1/15

N2 - We investigated the optical absorption properties of Nb x Ti 1−x O 2 thin films, a solid solution combining the reduced titanium and niobium oxide phases TiO 2 and NbO 2. The optical absorption properties of Nb x Ti 1−x O 2 thin films prepared by pulsed laser deposition at 600 °C were shown to be large in magnitude at an almost constant value of ≈17 µm −1 . Because this large absorption coefficient is nearly independent of incident photon energy in the visible range (400–700 nm), the Nb x Ti 1−x O 2 thin films appear optically black. Flat and homogenous, optically black coatings like these are desirable for color isolation in flat panel displays. The origin of flat wavelength dispersion in Nb x Ti 1−x O 2 is the coexistence of semiconducting absorption and metallic light absorption mechanisms. Localized Nb-Nb dimers in the metallic Nb x Ti 1−x O 2 phase open an optical band gap which gives rise to semiconducting behavior. We show here that reduction results in strong visible light sensitization in normally transparent Nb-Ti oxides.

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