Journal of the Korea Institute of Information and Communication Engineering (한국정보통신학회논문지)

The Korea Institute of Information and Commucation Engineering (한국정보통신학회)
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Effect of Substrate temperatures and Working pressures on the properties of the AI-doped ZnO thin films

기판온도 및 공정압력이 Aldoped ZnO 박막의 특성에 미치는 영향

  • 강성준 (전남대학교 전기 및 반도체공학과) ;
  • 정양희 (전남대학교 전기 및 반도체공학과)
  • Received : 2009.09.29
  • Accepted : 2009.10.06
  • Published : 2010.03.31
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Abstract

In this study Al-doped ZnO (AZO) thin films have been fabricated on Eagle 2000 glass substrates at various substrate temperature ($100{\sim}500^{\circ}C$) and working pressure (10 ~ 40 mTorr) by RF magnetron sputtering in order to investigate the structural, electrical, and optical properties of the AZO thin films. The obtained films were polycrystalline with a hexagonal wurtzite structure and preferentially oriented in the (002) crystallographic direction. The AZO thin films, which were deposited at $T=300^{\circ}C$ for 10 mTorr, shows the highest (002) orientation, and the full width at half maximum (FWHM) of the (002) diffraction peak is $0.42^{\circ}$. The lowest resistivity ($2.64{\times}10^{-3}\;{\Omega}cm$) with the highest cartier concentration ($5.29{\times}10^{20}\;cm^{-3}$) and a Hall mobility of ($6.23\;cm^2/Vs$) are obtained in the AZO thin films deposited at $T=300^{\circ}C$ for 10 mTorr. The optical transmittance in the visible region is approximately 80%, regardless of process conditions. The optical band-gap depends on the Al doping level as the substrate temperature increases and the working pressure decrease. The optical band-gap widening is proportional to cartier concentration due to the Burstein-Moss effect.

본 연구에서는 RF magnetron sputtering 법으로 AZO 세라믹 타켓 ($Al_2O_3$ : 3 wt%)을 이용하여 Eagle 2000 유리 기판위에 기판온도 ($100{\sim}500^{\circ}C$)와 공정압력 (10 ~ 40 mTorr)에 따른 AZO 박막을 제작하여, 결정화 특성과 전기적 및 광학적 특성을 조사하였다. 모든 AZO 박막은 육방정계구조를 가지는 다결정 이었고, (002)우선 배향성이 관찰되었다. 기판온도 $300^{\circ}C$, 10 mTorr에서 제작한 AZO 막에서 가장 우수한 (002) 배향성을 나타냈으며, 이때의 반가폭 값은 $0.42^{\circ}$였다. 전기적 특성은 기판온도 $300^{\circ}C$, 10 mTorr에서 가장 낮은 비저항 $2.64{\times}10^{-3}\;{\Omega}cm$과 우수한 캐리어 농도 및 이동도를 $5.29{\times}10^{20}\;cm^{-3}$, $6.23\;cm^2/Vs$를 나타내었다. 모든 AZO 박막은 가시광 영역에서 80%의 투과율을 나타내었으며, 기판온도 증가와 공정압력 감소에 따른 Al 도핑효과의 증가로 밴드 갭이 넓어지는 Burstein-Moss 효과가 관찰 되었다.

Keywords

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