Korean Journal of Materials Research (한국재료학회지)

Materials Research Society of Korea (한국재료학회)
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Effect of RF Powers on the Electro·optical Properties of ZnO Thin-Films

RF 출력이 ZnO 박막의 전기·광학적 특성에 미치는 영향

  • Shin, Dongwhee (Department of Material Engineering and Research Center for Infotronic Material and Devices, Hanbat National University) ;
  • Byun, Changsob (Department of Material Engineering and Research Center for Infotronic Material and Devices, Hanbat National University) ;
  • Kim, Seontai (Department of Material Engineering and Research Center for Infotronic Material and Devices, Hanbat National University)
  • 신동휘 (한밭대학교 신소재공학부 및 정보전자부품소재연구소) ;
  • 변창섭 (한밭대학교 신소재공학부 및 정보전자부품소재연구소) ;
  • 김선태 (한밭대학교 신소재공학부 및 정보전자부품소재연구소)
  • Received : 2012.07.24
  • Accepted : 2012.09.13
  • Published : 2012.10.27
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Abstract

ZnO thin films were grown on a sapphire substrate by RF magnetron sputtering. The characteristics of the thin films were investigated by ellipsometry, X-ray diffraction (XRD), atomic force microscopy (AFM), photoluminescence (PL), and Hall effect. The substrate temperature and growth time were kept constant at $200^{\circ}C$ at 30 minutes, respectively. The RF power was varied within the range of 200 to 500 W. ZnO thin films on sapphire substrate were grown with a preferred C-axis orientation along the (0002) plan; X-ray diffraction peak shifted to low angles and PL emission peak was red-shifted with increasing RF power. In addition, the electrical characteristics of the carrier density and mobility decreased and the resistivity increased. In the electrical and optical properties of ZnO thin films under variation of RF power, the crystallinity improved and the roughness increased with increasing RF power due to decreased oxygen vacancies and the presence of excess zinc above the optimal range of RF power. Consequently, the crystallinity of the ZnO thin films grown on sapphire substrate was improved with RF sputtering power; however, excess Zn resulted because of the structural, electrical, and optical properties of the ZnO thin films. Thus, excess RF power will act as a factor that degrades the device characteristics.

Keywords

References

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