| Summary: | 碩士 === 國立清華大學 === 材料科學工程學系 === 100 === Nowadays, many studies about fabricating electron devices and circuit design on paper substrate have increased. Paper is not only cheap but also recyclable that it becomes very potential which compared with polymer substrate. In our study, pentacene organic thin film transistors (OTFTs) were fabricated on art paper with silk fibroin as gate dielectric. Art paper was chosen as the substrate, which was obtained from bookshop without extra treatment before using. Surface roughness and water absorption are two primary drawbacks when art paper is utilized as the substrate for the fabrication of pentacene OTFTs with silk fibroin as the gate dielectric. The surface roughness of art paper can be compensated by depositing thick Cu gate electrodes (500 nm) onto the art paper. Moreover, the thick Cu gate electrodes can almost fill the microvoids of art paper but with nanoscale crack lines left over the surface. These would be explained by both the scanning electron microsopy (SEM) and Atomic Force Microscopy (AFM) analysis. The high casting temperature (100 oC) is required for water molecules to evaporate fast enough before being absorbed by the art paper, which results in a better device performance of OTFTs compared to 50 oC.
In many kinds of methods of casting silk fibroin film, the spray process was chosen because the highest performance of OTFTs devices were obtained in our study. The pentacene OTFTs on art paper exhibits very good device performance including a high mobility of 12.2 cm2 V-1 s-1, a threshold voltage of -0.55 V, a subthreshold swing of 365 mV/decade, and on/off ratio about 1x103.
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