Post-annealing-free solution-processed ultrathin Indium-Gallium-Oxide (IGO) channel for flexible thin film transistors

ABSTRACT Solution-processed oxide semiconductors are promising for low-cost, large-area flexible electronics. However, conventional multi-step deposition and prolonged thermal annealing reduce throughput. In addition, the uncontrolled accumulation of precursors leads to nonuniform thickness, hindering ultrathin channel formation. Unlike traditional methods, spray pyrolysis not only enables post-annealing-free in situ growth but also inherently limits precursor supply through droplet-by-droplet delivery, enabling quasi-ALD-like self-limited growth for precise thickness control. Here, we demonstrate post-annealing-free ultrathin InGaO channels via spray pyrolysis at 300 °C. X-ray photoelectron spectroscopy and transmission electron microscopy confirm a chemically homogeneous ∼5 nm InGaO layer free of organic residues. The resulting thin-film transistors exhibit hysteresis-free operation, a high mobility of (54.98 ± 3.32) cm 2 ⸱V –1 ⸱s –1 , an I ON /I OFF ratio exceeding 10 8 , and a subthreshold swing of 126 mV/dec, along with excellent bias-stress stability at low gate voltages (<5 V). Therefore, Spray pyrolysis enables the scalable fabrication of ultrathin oxide channels for flexible electronics.