Korean Journal of Optics and Photonics (한국광학회지)

Optical Society of Korea (한국광학회)
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Optical Constant Measurements of Highly Conductive Carbon Nanotube Films by Using Time-domain Terahertz Spectroscopy

시분해 테라파 분광학을 이용한 고전도성 탄소나노튜브 박막의 광학계수 측정

  • Moon, J.Y. (Department of Physics and Division of Energy Systems Research, Ajou University) ;
  • Park, D.J. (Department of Physics and Division of Energy Systems Research, Ajou University) ;
  • Lim, J.H. (Department of Physics and Division of Energy Systems Research, Ajou University) ;
  • Rotermund, F. (Department of Physics and Division of Energy Systems Research, Ajou University) ;
  • Lee, S. (Department of Physics and Division of Energy Systems Research, Ajou University) ;
  • Ahn, Y.H. (Department of Physics and Division of Energy Systems Research, Ajou University)
  • 문진영 (아주대학교 에너지시스템학부 (물리학)) ;
  • 박두재 (아주대학교 에너지시스템학부 (물리학)) ;
  • 임종혁 (아주대학교 에너지시스템학부 (물리학)) ;
  • 이상민 (아주대학교 에너지시스템학부 (물리학)) ;
  • 이순일 (아주대학교 에너지시스템학부 (물리학)) ;
  • 안영환 (아주대학교 에너지시스템학부 (물리학))
  • Published : 2010.02.25
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Abstract

We performed time-domain terahertz (THz) spectroscopy to determine optical constants of highly conductive carbon nanotube (CNT) films. The CNT films have been fabricated on a flexible plastic substrate by using spin-coating or vacuum filtration. We found that the transmission of THz waves can be controlled by manipulating the thickness of the films and by post-treatments. From amplitude and phase information of the transmitted THz waves, we obtain optical constants such as refractive indices and dielectric constants of the CNT films. The frequency dependent dielectric constants show good metallic behaviors, relevant to the Drude free electron models with high plasma frequencies. It is also found that the dielectric constants are higher for the acid-treated films. Finally, the frequency dependent dielectric constants which are free from substrate effects have been demonstrated by using CNT films deposited on cellulose membranes.

본 연구에서는 전도성이 매우 높은 탄소나노튜브 박막을 제작하고 테라파 영역에서의 광학상수를 측정하였다. 탄소나노튜브박막은 스핀코팅법 또는 진공여과법을 이용하여 연성플라스틱 기판 위에 증착되었다. 테라파 영역의 전자파 투과율은 박막의 두께조절을 통해 가능하며, 산처리 등의 후속공정을 통해서도 조절이 가능하다. 시분해 테라파 투과파의 진폭과 위상 측정을 통해유전상수를 포함한 광학상수의 스펙트럼을 측정하였다. 이를 통해 탄소나노튜브 박막이 Drude 자유전자 모델에 잘 부합하며, 높은 플라즈마 진동수를 가지는 등, 우수한 금속의 특성을 가지고 있음이 밝혀졌다. 또한 산처리 전후 유전상수가 변화하는 것을 직접확인할 수 있었다. 마지막으로 셀룰로즈 멤브레인에 증착된 CNT 필름의 경우엔 기판의 효과가 제거된 광학계수 측정이 가능함을 보여준다.

Keywords

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