| Summary: | 碩士 === 南台科技大學 === 機械工程系 === 97 === The purpose of this study is to investigate the influences of different proportion
of doping (0.5~10%) and different growth behaviors on the micro-structural, optical
and electrical properties of ZnO thin films and to find the best proportion of doping so
that high quality of transparent conductive films can be obtained.
In this experiment, the precursor was prepared by sol-gel method. First, Zinc
acetate dehydrate was added into methanol. Then, MEA was added as stabilizer.
Afterwards, adequate amount of metallic ions (Ga) were added to increase carrier
concentration so that conductivity could be enhanced, too. Next, spin-coating was
carried out on a glass substrate (corning 1737). After heat-treatments, the films were
obtained.
Both Ga doped ZnO and Al doped ZnO provide one electron (Ga3＋or Al3 to
substitute Zn2＋) to increase the carrier concentration and lower the resistance. Since
the radius of Ga ion (0.62 Å ) is similar to the radius of Zn ion (0.74 Å ), lattices are
not easily deformed during the process of doping. Besides, Ga and Zn have similar
electronegativity (Ga:1.13, Zn:0.99). Thus, as doping Ga is more suitable than Al. The
specimens were analyzed by SE, UV-Vis-NIR, Hall, XRD, XPS and SEM .
Experimental results show that the lowest resistance, 2.2×10-3Ω-cm , was obtained
with 1.0 at.% Ga. The transmittance of the GZO films was over 80% . The
crystallographic orientation of the GZO films shows the preferred direction of (002)
and (103). XPS data show that the infrared heating process can efficiently enhance the
production of oxygen vacancy when the doped films were annealed under vacuum.
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