Journal of the Semiconductor & Display Technology (반도체디스플레이기술학회지)

The Korean Society Of Semiconductor & Display Technology (한국반도체디스플레이기술학회)
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Effects of Hydrogen Injection by In-Situ and Plasma Post-Treatment on Properties of a ZnO Channel Layer in Transparent Thin Film Transistors

증착시 및 플라즈마 후처리에 의한 수소 주입이 투명 박막 트랜지스터에서 산화아연 채널층의 물성에 미치는 영향

  • Bang, Jung-Hwan (Dept. of Electronic, Electrical, Control and Instrumentation Engineering, Hanyang University) ;
  • Kim, Won (Dept. of Electronic, Electrical, Control and Instrumentation Engineering, Hanyang University) ;
  • Uhm, Hyun-Seok (Dept. of Electronic, Electrical, Control and Instrumentation Engineering, Hanyang University) ;
  • Park, Jin-Seok (Dept. of Electronic, Electrical, Control and Instrumentation Engineering, Hanyang University)
  • 방정환 (한양대학교 전자전기제어계측공학과) ;
  • 김원 (한양대학교 전자전기제어계측공학과) ;
  • 엄현석 (한양대학교 전자전기제어계측공학과) ;
  • 박진석 (한양대학교 전자전기제어계측공학과)
  • Published : 2010.03.31
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Abstract

We have investigated the effects of hydrogen injection via in-situ gas addition ($O_2$, $H_2$, or $O_2$ + $H_2$ gas) and plasma post-treatment (Ar or Ar + H plasma) on material properties of ZnO that is considered to be as a channel layer in transparent thin film transistors. The variations in the electrical resistivity, optical transmittance and bandgap energy, and crystal quality of ZnO thin films were characterized in terms of the methods and conditions used in hydrogen injection. The resistivity was significantly decreased by injection of hydrogen; approximately $10^6\;{\Omega}cm$ for as-grown, $1.2\;{\times}\;10^2\;{\Omega}cm$ for in-situ with $O_2/H_2\;=\;2/3$ addition, and $0.1\;{\Omega}cm$ after Ar + H plasma treatment of 90 min. The average transmittance of ZnO films measured at a wavelength of 400-700 nm was gradually increased by increasing the post-treatment time in Ar + H plasma. The optical bandgap energy of ZnO films was almost monotonically increased by decreasing the $O_2/H_2$ ratio in in-situ gas addition or by increasing the post-treatment time in Ar + H plasma, while the post-treatment using Ar plasma hardly affected the bandgap energy. The role of hydrogen in ZnO was discussed by considering the creation and annihilation of oxygen vacancies as well as the formation of shallow donors by hydrogen.

Keywords

References

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