Development of Atmospheric Pressure Plasma Jet System and the Improvement of Large Area Ga-doped ZnO Uniformity

There are several methods for coating transparent conductive oxide (TCO) thin films; Atmospheric Pressure Plasma Jet (APPJ) is one of those. The advantages for APPJ are: the deposition is done at the atmospheric environment, so we can save the cost of vacuum, which is used in the dominate sputtering system. With the assistance of plasma for enhancing chemical reaction, the substrate can be maintained at a relative low temperature. In this thesis, we developed a new APPJ system based on the system developed by Industrial Technology Research Institute (ITRI). with a goal to achieve a better uniformity of Ga-doped ZnO (GZO) film deposited on large-area substrate. Based on the findings from our previous collaboration with ITRI, we found that the air flow on the substrate plays an important role, so we redesigned the system to obtain a uniform and steady air flow by moving the exhaust fan from one side of the housing to directly beneath the table. Another key improvement is the beam fixed with plasma jet, which is designed as “box-like”, which not only enhances the stability and resonance frequency of the system, but also secures the precursor solution bottle. We also redesign the hardware and software of the scanning system. We wrote a graphic user interface by Visual Basic 6.0 which allows the users to design versatile scanning trajectories with ease. Finally we use NTU APPJ system to deposit GZO thin films and established a process baseline, which can be used as the basis for future improvement of thin film properties. Our results show significant improvement in uniformity and film properties over those obtained previously by the original ITRI system.