• Search Research Projects
  • Search Researchers
  • How to Use
  1. Back to previous page

Phase transition of thin films of organic conductors studied by scanning tunneling spectroscopy

Research Project

Project/Area Number 04650007
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field Applied materials
Research InstitutionHIROSHIMA UNIVERSITY

Principal Investigator

YOSHIMURA Masamichi  Hiroshima Univ., Dept.Electr.Eng., Assoc.Prof., 工学部, 助教授 (40220743)

Project Period (FY) 1992 – 1993
Project Status Completed (Fiscal Year 1993)
Budget Amount *help
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1993: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1992: ¥1,000,000 (Direct Cost: ¥1,000,000)
KeywordsTunneling microscopy / Tunneling spectroscopy / TTF-TCNQ / Organic thin film / Phase transition / Charge transfer complex / Low temperature / 走査トンネル分光法 / 導電性有機錯体 / BEDT-TTF
Research Abstract

We have investigated the surface electronic structure of thin films of an organic conductor TTF-TCNQ by scanning tunneling microscopy(STM) and scanning tunneling spectroscopy(STS), in order to understand the mechanism of Peierls transition of thin films at low temperature. In addition, we clarified some problems (described below) to be overcome in the STM measurement of organic films.
1. Experimental Set-up
Because of the higher vapor pressure, thin films of organic conductors were easily sublimated in ultra-high vacuum below 3x10^<-10> torr and eventually they vanished into vacuum after a long period. Then we used rather thick films as samples and performed STM/STS measurements in a short time. In addition, at low temperatures, the film was stripped away from the substrate and was unable to contact the electrode because of the difference in expansion coefficient between them. For this, organic thin films were prepared on the conductive Au film/mica.
2. Experimental Results
We obtained STM images of a TTF-TCNQ film at a tip voltage of 200mV, where three dots from a TCNQ molecule and one dot from a TTF molecule were arranged two-dimensionally on the surface. The I-V spectra showed metallic behavior at almost all the sampling points. At 77K, which was close to the critical temperature of Peierls transition (53K), the measurement was unstable and the I-V spectra showed both metallic and non-metallic characters depending on the sampling points, indicating that the transition already occurred at this temperature in a part of the sample. At 10K, the non-metallic phase became dominant, in which the spectra had a wide band-gap. We obtained STM images both at 77K and 10K, which were different from the image obtained at room temperature. Detailed interpretation of the images in conjunction with the phase transition is underway at present.

Report

(3 results)
  • 1993 Annual Research Report   Final Research Report Summary
  • 1992 Annual Research Report
  • Research Products

    (21 results)

All Other

All Publications (21 results)

  • [Publications] M.Yoshimura: "STM Study of organic thin films of BEDT-TTF iodide" Applied Surface Science. 60/61. 317-320 (1992)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] 河津璋: "走査型プローブ顕微鏡による有機伝導体薄膜の表面観察" 応用物理. 61. 1048-1052 (1992)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] M.Yoshimura: "Electronic Structure of the Organic Superconductor K-(BEDT-TTF)_2Cu(NCS)_2 Studied by Angle-Resolved Photemission Spectroscopy" Jpn.J.Appl.Phys.31. 1341-1342 (1992)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] K.Nakajima: "Observation of thin film of one-dimensional organic conductor TTF-TCNQ by means of atomic force microscopy" Applied Physics Letters. 62. 1892-1894 (1993)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] 重川秀実: "有機材料のSTM" 日本結晶学会誌. 35. 126-134 (1993)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] 河津璋: "導電性有機材料の観察・評価" 有機分子のSTMIAFM(共立出版). 101-123 (1993)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] M.Yoshimura: "STM Study of Organic Thin Films of BEDT-TTF lodide." Appl.Surf.Sci.60/61. 317-320 (1992)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] A.Kawazu: "Observation of Surfaces of Organic Thin Films" OYO BUTURI. 62. 1048-1052 (1992)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] M.Yoshimura: "Electronic Structure of the Organic Superconductor kappa-(BEDT-TTF)2Cu(NCS)2 Studied by Angle-Resolved Photoemission Spectroscopy" Jpn.J.Appl.Phys.31. 1341-1342 (1992)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] K.Nakajima: "Observation of Thin Film of One-dimensional Organic Conductor TTF-TCNQ by means of Atomic Force Microscopy" Appl.Phys.Lett.62. 1892-1894 (1993)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] H.Shigekawa: "STM on Organic Materials" J.Crystal.Soc.Jpn.35. 126-134 (1993)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] M.Yoshimura: "STM study of Organic thin films of BEDT-TTF iodide" Applied Surface Science. 60/61. 317-320 (1992)

    • Related Report
      1993 Annual Research Report
  • [Publications] 河津 璋: "走査型プローブ顕微鏡による有機伝導体薄膜の表面観察" 応用物理. 61. 1048-1052 (1992)

    • Related Report
      1993 Annual Research Report
  • [Publications] K.Nakajima: "Observation of thin film of one-dimensional organic conductor TTF-TCNQ by means of atomic force microscopy" Applied Physics Letters. 62. 1892-1894 (1993)

    • Related Report
      1993 Annual Research Report
  • [Publications] 重川秀実: "有機材料のSTM" 日本結晶学会誌. 35. 126-134 (1993)

    • Related Report
      1993 Annual Research Report
  • [Publications] 河津 璋: "導電性有機材料の観察・評価" 有機分子のSTM/AFM(共立出版). 101-123 (1993)

    • Related Report
      1993 Annual Research Report
  • [Publications] 河津 璋: "考査型プローブ顕微鏡による有機伝導体薄膜の表面観察" 応用物理. 61. 1048-1052 (1992)

    • Related Report
      1992 Annual Research Report
  • [Publications] K.NaKajima: "Observation of Thin Films of Organic One-dimensional Conductor TTF-TCNQ with use of Atomic Force Microscopy" Appl.Phys.Lett. (1993)

    • Related Report
      1992 Annual Research Report
  • [Publications] M.Yshimura: "STM study of Organic Thin Films of BEDT-TTF iodidc" Appl.Surf.Sci.60161. 317-320 (1992)

    • Related Report
      1992 Annual Research Report
  • [Publications] 重川 秀実: "有機材料のSTM" 日本結晶学会誌. (1993)

    • Related Report
      1992 Annual Research Report
  • [Publications] 河津 璋: "導電性有機材料の観察.評価" STM/AFM 午法の有機分子・バイオへの応用-評価観察から原子・分子ピンセットしての活用まで. (1993)

    • Related Report
      1992 Annual Research Report

URL: 

Published: 1992-04-01   Modified: 2016-04-21  

Information User Guide FAQ News Terms of Use Attribution of KAKENHI

Powered by NII kakenhi