Photoluminescence spectroscopic and computational investigation of the origin of the visible light response of (Ga1-xZnx)(N 1-xOx) photocatalyst for overall water splitting

Masaaki Yoshida, Takeshi Hirai, Kazuhiko Maeda, Nobuo Saito, Jun Kubota, Hisayoshi Kobayashi, Yasunobu Inoue, Kazunari Domen

Research output: Contribution to journalArticle

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Abstract

The electronic structure of a solid solution between GaN and ZnO, GaN-rich (Ga1-xZnx)(N1-xOx), was investigated by photoluminescence spectroscopy and a plane wave based density functional method. Photoluminescence excitation spectra (PLE) of (Ga1-xZn x)(N1-xOx) photocatalysts (x = 0.05-0.11) at 20 K had PLE edges in the UV region in addition to those of undoped GaN and Zn-doped GaN. However, the absorption edges appeared in the visible region, indicating that the intrinsic band gap of GaN-rich (Ga1-xZn x)(N1-xOx) solid solutions is derived from that of the GaN component. Photoluminescence (PL) bands of (Ga1-xZn x)(N1-xOx) photocatalysts were observed at 480 and 650 nm, suggesting that the luminescence originated from electron transitions from the conduction band to Ga vacancies as native defects, or to Zn acceptor levels as impurity levels. GaN-rich (Ga1-xZn x)(N1-xOx) material containing a large amount of oxygen is likely to produce an O donor level slightly below the conduction band minimum (CBM). The Zn acceptor level is likely to be filled with electrons derived from O donor levels or thermal excitation, suggesting that the absorption in the visible light region of this material occurs via electron transitions from the Zn acceptor level to the conduction band. The electronic structure and band gap narrowing are discussed in terms of density functional theory calculations using local nonstoichiometric defect structures modeled by Zn atom replacement, O atom replacement, or Ga atom vacancies.

Original languageEnglish
Pages (from-to)15510-15515
Number of pages6
JournalJournal of Physical Chemistry C
Volume114
Issue number36
DOIs
Publication statusPublished - 2010 Sep 16
Externally publishedYes

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water splitting
Photocatalysts
Conduction bands
Photoluminescence
Electron transitions
photoluminescence
Atoms
Vacancies
Electronic structure
Water
Solid solutions
Energy gap
conduction bands
Photoluminescence spectroscopy
Defect structures
electron transitions
Density functional theory
Luminescence
solid solutions
Impurities

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Electronic, Optical and Magnetic Materials
  • Surfaces, Coatings and Films
  • Energy(all)

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Photoluminescence spectroscopic and computational investigation of the origin of the visible light response of (Ga1-xZnx)(N 1-xOx) photocatalyst for overall water splitting. / Yoshida, Masaaki; Hirai, Takeshi; Maeda, Kazuhiko; Saito, Nobuo; Kubota, Jun; Kobayashi, Hisayoshi; Inoue, Yasunobu; Domen, Kazunari.

In: Journal of Physical Chemistry C, Vol. 114, No. 36, 16.09.2010, p. 15510-15515.

Research output: Contribution to journalArticle

Yoshida, Masaaki ; Hirai, Takeshi ; Maeda, Kazuhiko ; Saito, Nobuo ; Kubota, Jun ; Kobayashi, Hisayoshi ; Inoue, Yasunobu ; Domen, Kazunari. / Photoluminescence spectroscopic and computational investigation of the origin of the visible light response of (Ga1-xZnx)(N 1-xOx) photocatalyst for overall water splitting. In: Journal of Physical Chemistry C. 2010 ; Vol. 114, No. 36. pp. 15510-15515.
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AU - Maeda, Kazuhiko

AU - Saito, Nobuo

AU - Kubota, Jun

AU - Kobayashi, Hisayoshi

AU - Inoue, Yasunobu

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AB - The electronic structure of a solid solution between GaN and ZnO, GaN-rich (Ga1-xZnx)(N1-xOx), was investigated by photoluminescence spectroscopy and a plane wave based density functional method. Photoluminescence excitation spectra (PLE) of (Ga1-xZn x)(N1-xOx) photocatalysts (x = 0.05-0.11) at 20 K had PLE edges in the UV region in addition to those of undoped GaN and Zn-doped GaN. However, the absorption edges appeared in the visible region, indicating that the intrinsic band gap of GaN-rich (Ga1-xZn x)(N1-xOx) solid solutions is derived from that of the GaN component. Photoluminescence (PL) bands of (Ga1-xZn x)(N1-xOx) photocatalysts were observed at 480 and 650 nm, suggesting that the luminescence originated from electron transitions from the conduction band to Ga vacancies as native defects, or to Zn acceptor levels as impurity levels. GaN-rich (Ga1-xZn x)(N1-xOx) material containing a large amount of oxygen is likely to produce an O donor level slightly below the conduction band minimum (CBM). The Zn acceptor level is likely to be filled with electrons derived from O donor levels or thermal excitation, suggesting that the absorption in the visible light region of this material occurs via electron transitions from the Zn acceptor level to the conduction band. The electronic structure and band gap narrowing are discussed in terms of density functional theory calculations using local nonstoichiometric defect structures modeled by Zn atom replacement, O atom replacement, or Ga atom vacancies.

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