The Journal of Korean Institute of Electromagnetic Engineering and Science (한국전자파학회논문지)

The Korean Institute of Electromagnetic Engineering and Science (한국전자파학회)
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Spectroscopic Characterization of 400℃ Annealed ZnxCd1-xS Thin Films

400℃ 열처리한 삼원화합물 ZnxCd1-xS 박막의 분광학적 특성 연구

  • Kang, Kwang-Yong (Convergence of IT Devices Institute Busan, Dong-Eui University) ;
  • Lee, Seung-Hwan (Convergence of IT Devices Institute Busan, Dong-Eui University) ;
  • Lee, Nam-Kwon (Convergence of IT Devices Institute Busan, Dong-Eui University) ;
  • Lee, Jeong-Ju (Department of Physics and Research Institute of Natural Science, Gyeongsang National University) ;
  • Yu, Yun-Sik (Department of Radiological Science, Dong-Eui University)
  • 강광용 (동의대학교 부산IT융합부품연구소) ;
  • 이승환 (동의대학교 부산IT융합부품연구소) ;
  • 이남권 (동의대학교 부산IT융합부품연구소) ;
  • 이정주 (경상대학교 물리학과 및 기초과학연구소) ;
  • 유윤식 (동의대학교 방사선학과)
  • Received : 2014.10.27
  • Accepted : 2015.01.13
  • Published : 2015.01.30
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Abstract

II~VI compound semiconductors, $Zn_xCd_{1-x}S$ thin films have been synthesized onto indium-tin-oxide(ITO) coated glass substrates using thermal evaporation technique. The composition ratio x($0{\leq}x{\leq}1$) was varied to fabricate different kinds of $Zn_xCd_{1-x}S$ thin films including CdS(x=0) and ZnS(x=1) thin films. Then, the deposited thin films were thermally annealed at $400^{\circ}C$ to enhance their crystallinity. The chemical composition and electronic structure of films were investigated by using X-ray photoelectron spectroscopy(XPS). The optical energy gaps of the samples were determined by ultra violet-visible-near infrared(UV-Vis-NIR) spectroscopy and were found to vary in the range of 2.44 to 3.98 eV when x changes from 0 to 1. Finally, we measured the THz characteristics of the $Zn_xCd_{1-x}S$ thin films using THz-TDS(time domain spectroscopy) system to identify the capability for electronic and optical devices in THz region.

II~VI족 화합물 반도체 $Zn_xCd_{1-x}S$ 박막을 Indium-tin-oxide(ITO)가 도포된 유리기판 상에 열증발법을 사용하여 증착하였다. 박막의 합성비(molar ratio) x($0{\leq}x{\leq}1$)는 CdS(x=0) 박막과 ZnS(x=1) 박막을 포함하여, 삼원화합물 $Zn_xCd_{1-x}S$ 박막을 제조하기 위하여 변화시켰다. 또한, 증착한 박막의 결정성을 높이기 위하여 진공전기로에서 열처리 하였으며, 분광학적 특성조사를 위해서는 $400^{\circ}C$에서 열처리한 $Zn_xCd_{1-x}S$ 박막이 최적임을 알았다. $Zn_xCd_{1-x}S$ 박막의 합성비(x)와 전자적 구조를 조사하기 위하여 X-선 광전자 분광법(XPS)을 사용하였고, 박막시료의 광학적 에너지 띠 간격 $E_g$는 자외선-가시광-근접 적외선(UV-Vis-NIR) 분광법으로 측정하였으며, 합성비(x)값이 0에서 1까지 변화함에 따라 2.44~3.98 eV 범위의 값을 보여주었다. 끝으로, THz-TDS(Time Domain Spectroscopy) 시스템을 사용하고 $Zn_xCd_{1-x}S$ 박막의 THz파 특성을 측정하여 테라헤르츠(THz) 영역용 전자 및 광학 소자로서 응용가능성을 확인하였다.

Keywords

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