All Inkjet-Printed High On/Off Ratio Two-Dimensional Materials Field Effect Transistor
Date
2018-08
Authors
Jewel, Mohi Uddin
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Abstract
This thesis introduces the development of a novel ink, design, fabrication, and characterization of an all inkjet printed high current on/off ratio field effect transistor (FET). The inks were obtained through the liquid phase exfoliation of nitrogen-doped graphene (NDG), and molybdenum disulfide (MoS<sub>2</sub>) nanosheets into appropriate solvents. A stable and efficient method of inkjet printing is developed for NDG nanosheets. The concentration of nanosheets and the presence of MoS<sub>2</sub> were determined from UV-Vis spectra of the inks. The morphology of percolation clusters using NDG was studied using the thickness profile and scanning electron microscopy (SEM) images. The solvent-induced defects in NDG nanosheets were characterized by Raman spectroscopy. There were little or no solvent-induced defects in the nanosheets recovered by curing after printing. Barium titanate (BaTiO<sub>3</sub>) was prepared and used as a high <i>k (~20.5)</i> dielectric for the printed transistors. The NDG transistors were designed, fabricated, and characterized on the glass substrate. Due to the low on/off ratio of NDG transistors, NDG thin films were electrochemically doped with MoS<sub>2</sub> by multiple printing passes. The incorporation of semiconducting MoS<sub>2</sub> into NDG was confirmed by energy dispersive spectroscopy (EDS) for further analysis. A transistor with high current on/off ratio was obtained by NDG-MoS<sub>2</sub> heterostructures channel. To our best knowledge, this is the highest on/off ratio for a fully inkjet printed transistor based on 2D materials.
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Keywords
Fully printed, Doped graphene, Molybdenum disulfide, Transistor, Current on/off ratio, Switch, Inkjet printing
Citation
Jewel, M. U. (2018). <i>All inkjet-printed high on/off ratio two-dimensional materials field effect transistor</i> (Unpublished thesis). Texas State University, San Marcos, Texas.