Optimization and Characterization of Organic and Oxide Transistors

Abstract

The thesis work was carried out to optimize the performance of Gallium Indium Zinc Oxide (GIZO) Thin Film Transistors (TFT) on Foil, for display backchannel application. GIZO is an amorphous, optically transparent, large band gap (3.2 eV), semiconducting material. The TFT was fabricated with bottom gate – bottom contact architecture on PEN foil. Implementation of SiO2 encapsulation improved TFT stability. The best performance was obtained for GIZO TFT sputter deposited at low oxygen content; with field effect mobility of 14.31 cm2/Vs, threshold voltage of 2 V, good uniformity and relatively high stability against both positive and negative stress. The thesis work also involved optimization of organic TFT performance. The organic semiconducting material provided by a partner company called BASF was deposited using a new technique called Spray Coating, on bottom gate-bottom contact TFT architecture. The bottom gate dielectric surface was modified using alkyl SAM (Self Assembled Monolayer) before the deposition of organic active layer in order to improve the dielectric/active layer interface. It was observed that long alkyl chain SAM (with 18 carbon atoms) treated TFT showed the best performance with saturation mobility ~ 0.25 cm2/Vs and low hysteresis in transfer curve.