In2O3 thin-film transistors via inkjet printing for depletion-load nMOS inverters

Ability to digitally control the amount of a deposited material is one of the many advantages of inkjet printing. In this letter, we demonstrate the applicability of inkjet printing for the fabrication of depletion-load nMOS inverters based on metal oxide thin-film-transistors (TFTs) from printed metal oxide precursors where the threshold voltage of the TFTs is controlled by adjusting the thickness of the deposited semiconductor layer. Enhancement- and depletion-mode n-type In2O3 TFTs were fabricated from In-nitrate precursor using two printing strategies: 1) multilayer multinozzle printing and 2) single-layer single-nozzle printing in perpendicular or parallel to the TFT channel. TFTs with saturation mobility up to ~2.4 cm2/(V · s) and the ON/OFF-ratio of 107 were obtained after annealing at 300 °C. Devices connected as depletion-load nMOS inverters showed gain up to ~26 on a Si/SiO2 substrate, and an inverter on a flexible polyimide substrate with atomic layer deposited Al2O3 dielectric was demonstrated with a maximum gain of ~45