Characteristics of Al-doped ZnO thin films prepared by sol-gel method

AI-doped ZnO(AZO) thin films have been fabricated on glass substrate by sol-gel method, and the effect of Al precursors and post-annealing temperature on the characteristics of AZO thin films was investigated. The sol was prepared with zinc acetate, EtOH, MEA and Al precursors. In order to dope Al in ZnO, two types of aluminum nitrate and aluminum chloride were used as Al precursor. Zinc concentration was 0.5 mol/l and the content of Al precursor was 1 at% of Zn in the sol. The sol was spin-coated on glass substrate, and the coated films were annealed at 550ue for 2 hand were post-annealed at temperature ranges of $300{\sim}500^{\circ}C$ for 2 h in reducing atmosphere ($N_2/H_2$= 9/1). Structural, electrical and optical propertis of the fabricated AZO thin films were analyzed by XRD, FE-SEM, AFM, hall effect measurement system and UV-visible spectroscopy. Optical and electrical properties of AZO thin films prepared with aluminum nitrate as Al precursor were better than those of films prepared with aluminum chloride. The electrical resistivity and the optical transmittance of films decreased with increasing post-annealing temperatures. The minimum electrical resistivity of $2{\times}10^{-3}$ and the maximum optical transmittance of 91% were obtained for the AZO thin films post-annealed at $550^{\circ}C\;and\;300^{\circ}C$, respectively.

졸-겔법으로 제조한 Al-doped ZnO 박막의 특성에 관한 연구

졸-겔 공정을 이용하여 유리기판 위에 Al-doped ZnO(AZO) 박막을 제조하였고, AZO 박막의 특성에 대하여 Al 전구체 종류 및 post-annealing 온도가 미치는 영향에 대하여 고찰하였다. AZO 박막 제조용 졸은 zinc acetate, EtOH, MEA 등을 사용하여 제조하였고, Al doping 을 위한 전구체로는 aluminum nitrate 와 aluminum chloride 를 사용하였다. Sol 내의 Zn 농도는 0.5 mol/l 로 하였고, Al doping 양은 Zn 대비 1 at%로 고정하였다. 유리기판 위에 졸을 spin-coating 한 후 $550^{\circ}C$에서 2 시간 동안 열처리한 후, $N_2$와 $H_2$의 비가 9 : 1인 환원 분위기 내에서 $300^{\circ}C,\;400^{\circ}C,\;500^{\circ}C$인 온도에서 2시간 동안 post-annealing을 진행하였다. 제조된 AZO 박막의 구조적, 전기적, 광학적 특성은 XRD, FE-SEM, AFM, Hall effect measurement system 및 UV-Visible spectroscopy를 이용하여 분석하였다. Al 전구체로서 aluminum nitrate 를 사용한 경우가 aluminum chloride 를 사용하여 제조한 AZO 박막보다 우수한 광학적, 전기적 특성을 나타내었으며, post-annealing 온도가 증가함에 따라 비저항과 투과율은 감소하였다. $500^{\circ}C$에서 post-annealing한 AZO 박막의 전기비저항 값은 $2{\times}10^{-3}{\Omega}{\cdot}cm$이었고, 투과율은 $300^{\circ}C$에서 91%로 가장 높게 나타났다.