Deep-UV-Enhanced Approach for Low-Temperature Solution Processing of IZO Transistors with High-k AlO_x/YAlO_x Dielectric

Solution processing is an attractive alternative to standard vacuum fabrication techniques for the large-area manufacturing of metal oxide (MOx)-based electron devices. Here, we report on thin-film transistors (TFTs) based on a solution-processed indium zinc oxide (IZO) semiconductor utilizing a deep-ultraviolet (DUV)-enhanced curing, which enables a reduction of the annealing temperature to 200 °C. The effects of the DUV light exposure and the subsequent post-annealing parameters on the chemical composition of the IZO films have been investigated using Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. The semiconductor layer has been combined with an high-k aluminum oxide/yttrium aluminum oxide (AlOx/YAlOx) dielectric stack to realize fully solution-processed MOx TFTs at low temperature. The IZO/AlOx/YAlOx TFTs treated for 20 min DUV followed by 60 min at 200 °C exhibited Ion/Ioff of >108, a subthreshold slope (SS) of <100 mV dec–1, and mobility (μsat) of 15.6 ± 4 cm2 V–1 s–1. Devices realized with a reduced semiconductor curing time of 5 min DUV and 5 min at 200 °C achieved Ion/Ioff of >108, a SS <100 mV dec–1, and μsat of 2.83 ± 1.4 cm2 V–1 s–1. The TFTs possess high operational stability under gate bias stress, exhibiting low shifts in the threshold voltage of <1 V after 1000 s. The DUV-enhanced approach reduces the thermal budget required for the curing of solution-processed IZO semiconductors films, paving the way for its further implementation on temperature-sensitive substrates in future.