Inkjet-printed InGaZnO thin film transistor

We report inkjet-printed InGaZnO (IGZO) thin film transistors (TFTs). IGZO ink was prepared by dissolving indium nitrate hydrate, gallium nitrate hydrate and zinc acetate dihydrate into 2-methoxyethanol with additional stabilizers. The resulting films were inkjet-printed with a resolution of 300 dots per inch using droplets with a diameter of 40 µm, and a volume of 35 pl. The films exhibited high optical transparency in the visible range and had a polycrystalline phase of InGaO3(ZnO)2 after thermal annealing treatment. The chemical composition of this IGZO sample was also determined, and shown to have high stoichiometric characteristics of low oxygen deficiency. The TFTs with a conventional inverted staggered structure using inkjet-printed IGZO as an active channel layer had a field-effect mobility of ~ 0.03 cm2/Vs in saturation region and an on-to-off current ratio greater than ~ 104.