Wet processed ZnO films for semiconductor layers bring positive impact on fabrication of field-effect transistors (FETs) in terms of their low process temperature and manufacturing cost reduction. In our work, with the aim of fabricating organic light-emitting transistors (OLETs) using transparent ZnO FETs as the driver transistors, we have fabricated a wet processed ZnO film as a semiconductor layer, and investigated the effects of ultraviolet/ozone (UV/O 3 )-assisted thermal treatments on ZnO FET characteristics. The results on the carrier mobility and thermal treatment temperature of ZnO films showed that the carrier mobility is almost proportional to treatment temperature, and the UV/O 3 -assisted thermal treatment lowers the thermal treatment temperature. Moreover, devices subjected to UV/O 3 -assisted thermal treatments showed excellent electrical characteristics compare with devices without the treatments. These results show that the UV/O 3 -assisted thermal treatment is expected to facilitate OLET fabrication on flexible plastic films.

The usual silicon-based display back planes require fairly high process temperature and thus the development of a low temperature process is needed on flexible plastic substrates. A new type of flexible organic light emitting transistor (OLET) had been proposed and investigated in the previous work. By using ultraviolet/ozone (UV/O3) assisted thermal treatments on wet processed zinc oxide field effect transistor (ZnO-FET), through low-process temperature, ZnO-FETs were fabricated which succeeded to achieve target drain current value and mobility. In this study, physical property evaluation of ZnO was conducted in term of their crystallinity, the increase composition of ZnO formed inside the thin film and the decrease of the carbon impurities originated from aqueous solution of the ZnO itself. The X-ray diffraction (XRD) evaluation showed UV/03 assisted thermal treatment has no obvious effect towards crystallinity of ZnO in the range of low process temperature. Moreover, through X-ray photoelectron spectroscopy (XPS) evaluation and Fourier transform infrared (FT-IR) spectroscopy evaluation, more carbon impurities disappeared from the ZnO thin film and the increase of composition amount of ZnO, when the thin film was subjected to UV/O3 assisted thermal treatment. Therefore, UV/O3 assisted thermal treatment contributed in carbon impurities elimination and accelerate ZnO formation in ZnO thin film, which led to the improvement in the electrical property of ZnO-FET in the low-process temperature.

In this paper, we design magnetic levitation system that deals with the knowledge of electromagnetism and the control switching application. The concept of this design is to achieve the state of equilibrium where the magnetic attraction counterbalances the force of gravity pulling on an object. The control system in this design is formed by a PIC Microcontroller and several op-amps. Using photo sensors to provide a feedback loop, the control system employs a closed-loop control in controlling the current through the electromagnet.