Real-time observation of carrier dynamics at oxide semiconductor and metal interfaces

• Project/Area Number: 25870193
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Quantum beam science; Thin film/Surface and interfacial physical properties
• Research Institution: The University of Tokyo
• Principal Investigator: Yamamoto Susumu 東京大学, 物性研究所, 助教 (50554705)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Project Status: Completed (Fiscal Year 2015)
• Budget Amount: ¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000); Fiscal Year 2015: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000); Fiscal Year 2014: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000); Fiscal Year 2013: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
• Keywords: 時間分解 / 光電子分光 / 放射光 / キャリアダイナミクス / 酸化物半導体 / 光触媒 / 時間分解光電子分光

Outline of Final Research Achievements

This study aimed to investigate site-specific carrier dynamics at oxide semiconductor and metal interfaces using time-resolved soft X-ray photoelectron spectroscopy. The relaxation time of photo-excited carriers at oxide surfaces were obtained by monitoring in real time the peak shift of core-level spectra due to a surface photovoltage effect.
The relaxation time of photo-excited carriers on the clean ZnO(0001) surface was about a few 10s ns, and decreased largely to below 1 ns on the Pt-deposited ZnO(0001) surface. The origin of shorter lifetime of photo-excited carriers could be the increase of the carrier recombination centers on the oxide surface by Pt deposition.

Research Products

• [Journal Article] Capturing transiently charged states at the C60/TiO2(110) interface by time-resolved soft X-ray photoelectron spectroscopy (2016)
  • Author(s): Kenichi Ozawa, Susumu Yamamoto, Ryu Yukawa, Kazuma Akikubo, Masato Emori, Hiroshi Sakama, Iwao Matsuda
  • Journal Title: Organic Electronics Volume: 31 Pages: 98-103
  • DOI: 10.1016/j.orgel.2016.01.020
  • Peer Reviewed
• [Journal Article] Time-Resolved Soft X-ray Photoelectron Spectroscopy: Real-Time Observation of Photo-Excited Carriers at Semiconductor Surfaces (2016)
  • Author(s): 山本達、松田巌
  • Journal Title: Hyomen Kagaku Volume: 37 Issue: 1 Pages: 9-13
  • DOI: 10.1380/jsssj.37.9
  • NAID: 130005121621
  • ISSN: 0388-5321, 1881-4743
  • Peer Reviewed
• [Journal Article] Anisotropic effective mass approximation model to calculate multiple subband structures at wide-gap semiconductor surfaces: Application to accumulation layers of SrTiO3 and ZnO (2015)
  • Author(s): R. Yukawa, K. Ozawa, S. Yamamoto, R.-Y. Liu, I. Matsuda
  • Journal Title: Surface Science Volume: 641 Pages: 224-230
  • DOI: 10.1016/j.susc.2015.07.007
  • Peer Reviewed
• [Journal Article] Electron-hole recombination on ZnO(0001) single-crystal surface studied by time-resolved soft X-ray photoelectron spectroscopy (2014)
  • Author(s): R. Yukawa, S. Yamamoto, K. Ozawa, M. Emori, M. Ogawa, Sh. Yamamoto, K. Fujikawa, R. Hobara, S. Kitagawa, H. Daimon, H. Sakama, I. Matsuda,
  • Journal Title: Applied Physics Letters Volume: 105 Issue: 15 Pages: 151602-151602
  • DOI: 10.1063/1.4897934
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] 時間分解軟X線光電子分光法による表面キャリアダイナミクス研究の進展 (2014)
  • Author(s): 山本達、松田巌、
  • Journal Title: 日本放射光学会誌「放射光」 Volume: 27 Pages: 241-252
  • NAID: 40020228946
  • Peer Reviewed
• [Presentation] 酸化物半導体・金属界面における光励起キャリアのリアルタイム観察 (2016)
  • Author(s): 山本達, 竹内圭織, 松田巌
  • Organizer: 日本物理学会第71回年次大会
  • Place of Presentation: 東北学院大学（宮城県仙台市）
  • Year and Date: 2016-03-19
• [Presentation] VUV・軟X線光源を用いた表面キャリア・分子ダイナミクス研究 (2016)
  • Author(s): 山本達
  • Organizer: 東大放射光アウトステーションH27年度播磨研究報告会
  • Place of Presentation: 姫路市市民会館（兵庫県姫路市）
  • Year and Date: 2016-02-10
• [Presentation] Probing carriers and molecules on oxide surfaces by X-ray (2016)
  • Author(s): S. Yamamoto
  • Organizer: 11th SOLEIL users' meeting
  • Place of Presentation: Paris (France)
  • Year and Date: 2016-01-21
  • Int'l Joint Research / Invited
• [Presentation] 半導体表面における光励起キャリアのリアルタイム観測：時間分解軟X線光電子分光法 (2015)
  • Author(s): 山本達
  • Organizer: 物性研・物構研連携研究会
  • Place of Presentation: 高エネルギー加速器研究機構（茨城県つくば市）
  • Year and Date: 2015-08-06
• [Presentation] 時間分解放射光光電子分光 ～光触媒、太陽電池のエネルギー変換を担うキャリアをリアルタイムで追跡！～ (2015)
  • Author(s): 山本達
  • Organizer: 日本表面科学会関東支部 第1回関東支部セミナー
  • Place of Presentation: 東京大学本郷キャンパス（東京都文京区）
  • Year and Date: 2015-05-22
  • Int'l Joint Research
• [Presentation] 時間分解軟Ｘ線光電子分光法による表面キャリアダイナミクス研究の現状と今後の展望 (2015)
  • Author(s): 山本達
  • Organizer: ISSP workshop「SPring-8 BL07LSUの現状と新たな光源に向けた取り組み」
  • Place of Presentation: 東京大学物性研究所（千葉県柏市）
  • Year and Date: 2015-03-05
• [Presentation] 時間分解軟Ｘ線光電子分光法による表面キャリアダイナミクスの研究 (2014)
  • Author(s): 山本達
  • Organizer: 兵庫県立大学大学院物質理学研究科多重極限物質科学研究センター研究発表会
  • Place of Presentation: 兵庫県立大学（兵庫県赤穂郡）
  • Year and Date: 2014-12-25
  • Invited
• [Presentation] Carrier dynamics on oxide surfaces studied by time-resolved soft x-ray photoelectron spectroscopy (2014)
  • Author(s): S. Yamamoto, R. Yukawa, M. Emori, K. Ozawa, M. Ogawa, K. Fujikawa, Sh. Yamamoto, R. Hobara, S. Kitagawa, H. Daimon, I. Matsuda,
  • Organizer: The 7th International Symposium on Surface Science (ISSS-7)
  • Place of Presentation: くにびきメッセ(島根県松江市）
  • Year and Date: 2014-11-04
• [Presentation] Tracking photo-excited carriers on semiconductor surfaces by x-ray (2014)
  • Author(s): S. Yamamoto
  • Organizer: MPI-P Bonn group seminar
  • Place of Presentation: Mainz (Germany)
  • Year and Date: 2014-09-10
• [Presentation] Relaxation processes of photo-excited carriers on the atomically-controlled semiconductor surfaces studied by time-resolved soft x-ray photoelectron spectroscopy (2014)
  • Author(s): S. Yamamoto, M. Ogawa, K. Fujikawa, R. Hobara, R. Yukawa, Sh. Yamamoto, S. Kitagawa, D. Pierucci, M.G. Silly, C.-H. Lin, R.-Y. Liu, H. Daimon, F. Sirotti, S.-J. Tang, I. Matsuda,
  • Organizer: 30th European Conference on Surface Science (ECOSS-30)
  • Place of Presentation: Antalya (Turkey)
  • Year and Date: 2014-09-02
• [Presentation] 時間分解光電子分光法による半導体表面キャリアダイナミクス研究の現状と展望 (2014)
  • Author(s): 山本達
  • Organizer: 東京大学放射光アウトステーション報告会「SPring-8 BL07LSUの現状と第II期への展望」
  • Place of Presentation: 東京大学物性研究所（千葉県）
• [Presentation] Carrier dynamics on oxide surfaces studied by time-resolved soft x-ray photoelectron spectroscopy (2013)
  • Author(s): S. Yamamoto, R. Yukawa, M. Emori, K. Ozawa, M. Ogawa, K. Fujikawa, Sh. Yamamoto, R. Hobara, I. Matsuda
  • Organizer: American Vacuum Society 60th International Symposium
  • Place of Presentation: Long Beach, California, US
• [Presentation] 時間分解軟X線光電子分光法でみる半導体表面キャリアダイナミクス (2013)
  • Author(s): 山本達
  • Organizer: 放射光学会第５回若手研究会「パルス特性を用いた次世代材料研究の最前線」
  • Place of Presentation: 東京大学物性研究所（千葉県）
• [Remarks] 山本達研究用ホームページ
  • URL: http://www.issp.u-tokyo.ac.jp/labs/sor/s-yamamoto/
• [Remarks] 山本達研究用ホームページ
  • URL: http://www.issp.u-tokyo.ac.jp/labs/sor/s-yamamoto/index-j.html