| Summary: | 碩士 === 國立交通大學 === 工學院碩士在職專班半導體材料與製程設備組 === 96 === In this study, we have developed a novel and environment-friendly aqueous method to deposit ZnO-based thin films, including ZnO, Zn1-xMgxO, and Zn1-xInxO material systems. For the first part, a new chemical solution has been synthesized for deposition of ZnO thin films on glass substrate by the aqueous method; for the second part of Zn1-x MgxO, Mg-contained chemicals were added into ZnO solution for film deposition; for the third part, we added indium-contained chemicals into ZnO solution. The deposited thin films were characterized by atomic force microscopy and scanning electron microscopy for the film morphology, x-ray diffraction (XRD) for the crystallinity, x-ray energy dispersive spectroscopy for the composition measurement, four-point probe method for the resistivities, and UV- visible spectrum analysis for transparencies. In addition, TFT devices were fabricated and the TFT characteristics were determined.
For ZnO film deposition, Zn(CH3COO)2．2H2O was dissolved in deion -ized (DI) water, followed by addition of some nonionic surfactant into the ZnO aqueous solution. After complete mixing of the solution under stirring, a clear and homogenous solution was obtained. The solution was then spin-coated on glass substrate, followed by pre-baking at 80 �aC and annealing at a temperature from 300 to 500 �aC. Finally, a continuous ZnO transparent thin film can be obtained. UV-Visible analysis shows that the transparency of the ZnO thin film in wavelength of 400~800nm is higher than 85%.
For Zn1-xMgxO system, some Zn(CH3COO)2．2H2O and Mg(CH3COO)2．4H2O were dissolved in deionized (DI) water. With addition of some nonionic surfactant into the Zn1-xMgxO aqueous solution, a clear and homogenous solution was obtained. After spin-coating on glass substrate, followed by pre-baking and annealing a continuous Zn1-xMgxO transparent thin film was formed. XRD shows that all the films are of single phase without MgO for x up to 0.4. UV-Visible analysis shows that the transparency of the Zn1-xMgxO thin films in wavelength of400~800nm can be higher than 90%.
For ZnInO (ZIO) system, Zn(NO3)2•6H2O and In(NO3)3•xH2O were used for dissolution in deionized water. Using the same processing as shown above for ZnO and ZnMgO, an almost continuous ZIO transparent thin film was obtained. However, XRD reveals that there is In2O3 crystalline phase in addition to ZnO in the films.
TFT devices were fabricated using ZnO, Zn0.9Mg0.1O, and ZIO. The electrical characterization shows that the ZIO TFT has the highest mobility of 0.8cm2/Vs
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