Achieving high-mobility and stable InGaO thin-film transistors by stacking InGaO films

Abstract Thin-film transistors (TFTs) based on indium oxide face inherent stability challenges due to oxygen vacancy accumulation, despite their high mobility. We address this trade-off by developing an atomic-layer-deposited (ALD) InGaO bilayer architecture combining an In-rich front channel with a Ga-stabilized back channel. Single-layer optimization for the back channel revealed coarse stacking exhibits better stability and appropriate ozone wait time reduced interfacial traps. The bilayer device achieves a high field-effect mobility of 77.5 cm2V−1s−1 alongside −1.10 V in negative bias thermal stability threshold voltage shift. This ALD-based structural engineering strategy provides an effective approach to decouple mobility-stability limitations in oxide TFTs.