Shallow electron traps formed by Gd2+ ions adjacent to oxygen vacancies in cerium-doped Gd3Al2Ga3O12 crystals

Mamoru Kitaura; Shinta Watanabe; Kei Kamada; Kyoung Jin Kim; Masao Yoshino; Shunsuke Kurosawa; Toru Yagihashi; Akimasa Ohnishi; Kazuhiko Hara

doi:10.1063/1.5043218

Shallow electron traps formed by Gd²⁺ ions adjacent to oxygen vacancies in cerium-doped Gd₃Al₂Ga₃O₁₂ crystals

Mamoru Kitaura, Shinta Watanabe, Kei Kamada, Kyoung Jin Kim, Masao Yoshino, Shunsuke Kurosawa, Toru Yagihashi, Akimasa Ohnishi, Kazuhiko Hara

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Abstract

To clarify the origin of shallow electron traps in cerium-doped Gd₃Al₂Ga₃O₁₂ (Ce:GAGG), the optical properties of cerium-doped Lu_3- _xGd_xAl₂Ga₃O₁₂ crystals were investigated. Absorption spectra for x = 3 exhibited a prominent band at 12 000 cm^-1 when excited by 3.31-eV ultraviolet light. This band has been previously attributed to shallow electron traps at defect complexes associated with oxygen vacancies. When Gd³⁺ ions were replaced with Lu³⁺ ions, the 12 000 cm^-1 band weakened and disappeared completely for Ce:Lu₃Al₂Ga₃O₁₂. In addition, thermally stimulated luminescence glow curves were observed. Optically stimulated luminescence indicated that the energy of the conduction band minimum did not change by the presence of Lu³⁺ ions. Thus, the Gd³⁺ ions were important for the formation of shallow electron traps in Ce:GAGG. First-principles calculations implied that Gd³⁺ ions responsible for shallow electron traps formed antisite defects at GAGG octahedral sites. Hence, defect complexes of antisite Gd²⁺ ions adjacent to oxygen vacancies were the most plausible candidates for shallow electron traps in Ce:GAGG.

Original language	English
Article number	041906
Journal	Applied Physics Letters
Volume	113
Issue number	4
DOIs	https://doi.org/10.1063/1.5043218
Publication status	Published - 2018 Jul 23

ASJC Scopus subject areas

Physics and Astronomy (miscellaneous)

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@article{8c9bdfad8c704c9d993a35001d47881e,

title = "Shallow electron traps formed by Gd2+ ions adjacent to oxygen vacancies in cerium-doped Gd3Al2Ga3O12 crystals",

abstract = "To clarify the origin of shallow electron traps in cerium-doped Gd3Al2Ga3O12 (Ce:GAGG), the optical properties of cerium-doped Lu3- xGdxAl2Ga3O12 crystals were investigated. Absorption spectra for x = 3 exhibited a prominent band at 12 000 cm-1 when excited by 3.31-eV ultraviolet light. This band has been previously attributed to shallow electron traps at defect complexes associated with oxygen vacancies. When Gd3+ ions were replaced with Lu3+ ions, the 12 000 cm-1 band weakened and disappeared completely for Ce:Lu3Al2Ga3O12. In addition, thermally stimulated luminescence glow curves were observed. Optically stimulated luminescence indicated that the energy of the conduction band minimum did not change by the presence of Lu3+ ions. Thus, the Gd3+ ions were important for the formation of shallow electron traps in Ce:GAGG. First-principles calculations implied that Gd3+ ions responsible for shallow electron traps formed antisite defects at GAGG octahedral sites. Hence, defect complexes of antisite Gd2+ ions adjacent to oxygen vacancies were the most plausible candidates for shallow electron traps in Ce:GAGG.",

author = "Mamoru Kitaura and Shinta Watanabe and Kei Kamada and {Jin Kim}, Kyoung and Masao Yoshino and Shunsuke Kurosawa and Toru Yagihashi and Akimasa Ohnishi and Kazuhiko Hara",

note = "Funding Information: This work was supported by KAKNHI (Grant No. 26420673) from the Japan Society for the Promotion of Science (JSPS), the Cooperative Research Project of Research Institute of Electronics, Shizuoka University, and the Inter-University Cooperative Research Program of the Institute for Materials Research, Tohoku University. DFT calculations using CASTEP were performed by using the “Computer System for Nanostructure Design” at Nagoya University, Venture Business Laboratory. This work was partially performed at the UVSOR synchrotron radiation facility at the Institute for Molecular Science, Okazaki. Publisher Copyright: {\textcopyright} 2018 Author(s).",

year = "2018",

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doi = "10.1063/1.5043218",

language = "English",

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T1 - Shallow electron traps formed by Gd2+ ions adjacent to oxygen vacancies in cerium-doped Gd3Al2Ga3O12 crystals

AU - Kitaura, Mamoru

AU - Watanabe, Shinta

AU - Kamada, Kei

AU - Jin Kim, Kyoung

AU - Yoshino, Masao

AU - Kurosawa, Shunsuke

AU - Yagihashi, Toru

AU - Ohnishi, Akimasa

AU - Hara, Kazuhiko

N1 - Funding Information: This work was supported by KAKNHI (Grant No. 26420673) from the Japan Society for the Promotion of Science (JSPS), the Cooperative Research Project of Research Institute of Electronics, Shizuoka University, and the Inter-University Cooperative Research Program of the Institute for Materials Research, Tohoku University. DFT calculations using CASTEP were performed by using the “Computer System for Nanostructure Design” at Nagoya University, Venture Business Laboratory. This work was partially performed at the UVSOR synchrotron radiation facility at the Institute for Molecular Science, Okazaki. Publisher Copyright: © 2018 Author(s).

PY - 2018/7/23

Y1 - 2018/7/23

N2 - To clarify the origin of shallow electron traps in cerium-doped Gd3Al2Ga3O12 (Ce:GAGG), the optical properties of cerium-doped Lu3- xGdxAl2Ga3O12 crystals were investigated. Absorption spectra for x = 3 exhibited a prominent band at 12 000 cm-1 when excited by 3.31-eV ultraviolet light. This band has been previously attributed to shallow electron traps at defect complexes associated with oxygen vacancies. When Gd3+ ions were replaced with Lu3+ ions, the 12 000 cm-1 band weakened and disappeared completely for Ce:Lu3Al2Ga3O12. In addition, thermally stimulated luminescence glow curves were observed. Optically stimulated luminescence indicated that the energy of the conduction band minimum did not change by the presence of Lu3+ ions. Thus, the Gd3+ ions were important for the formation of shallow electron traps in Ce:GAGG. First-principles calculations implied that Gd3+ ions responsible for shallow electron traps formed antisite defects at GAGG octahedral sites. Hence, defect complexes of antisite Gd2+ ions adjacent to oxygen vacancies were the most plausible candidates for shallow electron traps in Ce:GAGG.

AB - To clarify the origin of shallow electron traps in cerium-doped Gd3Al2Ga3O12 (Ce:GAGG), the optical properties of cerium-doped Lu3- xGdxAl2Ga3O12 crystals were investigated. Absorption spectra for x = 3 exhibited a prominent band at 12 000 cm-1 when excited by 3.31-eV ultraviolet light. This band has been previously attributed to shallow electron traps at defect complexes associated with oxygen vacancies. When Gd3+ ions were replaced with Lu3+ ions, the 12 000 cm-1 band weakened and disappeared completely for Ce:Lu3Al2Ga3O12. In addition, thermally stimulated luminescence glow curves were observed. Optically stimulated luminescence indicated that the energy of the conduction band minimum did not change by the presence of Lu3+ ions. Thus, the Gd3+ ions were important for the formation of shallow electron traps in Ce:GAGG. First-principles calculations implied that Gd3+ ions responsible for shallow electron traps formed antisite defects at GAGG octahedral sites. Hence, defect complexes of antisite Gd2+ ions adjacent to oxygen vacancies were the most plausible candidates for shallow electron traps in Ce:GAGG.

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Shallow electron traps formed by Gd²⁺ ions adjacent to oxygen vacancies in cerium-doped Gd₃Al₂Ga₃O₁₂ crystals

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