Deep-UV approaches and printing of indium zinc oxide thin-film transistors targeting their processing on thermosensitive substrates

Novel metal-oxides (MOx) semiconductors for thin-film transistors (TFTs) are being developed as they can offer superior electric performances over organic-based counterparts. MOx TFTs processed on foil could be exploited in smart labels as RFID and NFC tags, flexible wearable devices, interfaced with or like sensors for personalized healthcare, fulfilling the demand for device integration in daily life products. However, their current processing conditions do not enable large-area manufacturing on commonly used substrates in printed electronics, such as thermosensitive polyethylene-based foils, preventing their cost-effective diffusion in consumer and logistic products. This thesis addresses the solution processing at low temperature (109, comparable with state-of-the-art sputtered devices.Then, we implemented a DUV-enhanced protocol for the synthesis of spin-coated IZO semiconductor and printed AlOx/YAlOx dielectric at a low temperature of 200°C. Prolonged DUV exposure (1h) and thermal annealing (3h) yielded TFTs with u as high as ~40cm2/Vs. By studying the effects of the process parameters on IZO chemical composition and TFTs characteristics, the IZO synthesis time was shortened to ~1h while maintaining excellent performances such as u~16cm2/Vs, Ion/Ioff>108, and SS108, and SS1cm2/Vs. Finally, thermally annealed TFTs with printed MOx functional stack exhibiting u>4cm2/Vs were proven. Process tuning is still required to achieve fully printed IZO-AlOx/YAlOx TFTs on foil, but the preliminary results proved the suitability of both printing and synthesis approaches with cost-effective polymeric substrates.