Deep-UV-Enhanced Approach for Low-Temperature Solution\nProcessing of IZO Transistors with High‑<i>k</i> AlO<i>_x</i>/YAlO<i>_x</i> Dielectric

Abstract

Solution\nprocessing is an attractive alternative to standard vacuum fabrication\ntechniques for the large-area manufacturing of metal oxide (MO<i>_x</i>)-based electron devices. Here, we report on\nthin-film transistors (TFTs) based on a solution-processed indium\nzinc oxide (IZO) semiconductor utilizing a deep-ultraviolet (DUV)-enhanced\ncuring, which enables a reduction of the annealing temperature to\n200 °C. The effects of the DUV light exposure and the subsequent\npost-annealing parameters on the chemical composition of the IZO films\nhave been investigated using Fourier-transform infrared spectroscopy\nand X-ray photoelectron spectroscopy. The semiconductor layer has\nbeen combined with an high-<i>k</i> aluminum oxide/yttrium\naluminum oxide (AlO<i>_x</i>/YAlO<i>_x</i>) dielectric stack to realize fully solution-processed\nMO<i>_x</i> TFTs at low temperature. The IZO/AlO<i>_x</i>/YAlO<i>_x</i> TFTs treated\nfor 20 min DUV followed by 60 min at 200 °C exhibited <i>I</i>_on/<i>I</i>_off of >10⁸, a subthreshold slope (SS) of <100 mV dec^–1, and mobility (μ_sat) of 15.6 ± 4 cm² V^–1 s^–1. Devices realized with\na reduced semiconductor curing time of 5 min DUV and 5 min at 200\n°C achieved <i>I</i>_on/<i>I</i>_off of >10⁸, a SS <100 mV dec^–1, and μ_sat of 2.83 ± 1.4 cm² V^–1 s^–1. The TFTs possess high operational\nstability under gate bias stress, exhibiting low shifts in the threshold\nvoltage of <1 V after 1000 s. The DUV-enhanced approach reduces\nthe thermal budget required for the curing of solution-processed IZO\nsemiconductors films, paving the way for its further implementation\non temperature-sensitive substrates in future.