R.K. Sarvestani, B. Wright and K. Triyasakorn
Utah Valley University,
Keywords: inkjet printing, CNTFET
Summary:Fabrication of Differential Amplifiers Using Inkjet Printing and Single Wall Carbon Nanotubes Inkjet printing is a non-contact method in which small droplets of conductive material such as silver nanoparticle ink or functional material are deposited onto the substrate. Inkjet printing is getting higher demand in fabrication of low cost electronic circuits and transistor. A basic MOS differential-pair amplifier uses a pair of MOSFETs to amplify the difference in voltage between the gate-source voltages of both of the transistors. In this project inkjet printing was used for making FET transistors in a differential amplifier and carbon nanotube was used as semiconductor. Compared with the conventional printed circuit board (PCB) process, which uses a subtractive method of etching away metal foil, inkjet printing deposits droplets of conductive ink only where desired, eliminating extra costs and waste, and requiring fewer steps than traditional PCB manufacturing techniques. The differential amplifier was comprised of two thin-film transistors (TFT), two 100 Ω resistors, and two 10 k Ω resistors. The inkjet-printed patterns were created in Microsoft Paint as bitmap image files and imported into Dimatix Drop Manager to create printable patterns. Firstly, the gate was produced by printing a single layer of Mitsubishi Paper Mills silver-nanoparticle ink onto the paper substrate with a 10 μm drop spacing. A dielectric layer of graphene oxide water dispersion was then dropped by hand with the pico-pipette directly onto the gate with enough volume to completely cover the tip of the gate. After the graphene oxide was dry, the source and drain were printed with silver nanoparticle ink with a 10 μm drop spacing.. The source and drain were printed in the shape of two adjacent T shapes with a separation of 230 μm on top of the graphene layer CNT was diluted with distilled water at 1:9 ratio to allow for sufficient resistance. The CNT was then deposited by hand via pico-pipette on top of the source and drain with sufficient volume to cover the gap between them. The CNT was first diluted with distilled water at a ratio of 1:9 so that the CNT provided a sufficient resistance (~ 25kOhm) for use in the TFTs. After fabrication of the differential amplifier, it was tested using DC bias and it showed a good performance with drain to source voltage of +5 volts and a gate voltage in the range of -15 to +15 volts. This project covers design, theory, fabrication steps, and test of differential amplifiers using CNTFET.