Synergistic Approach to High-Performance Oxide Thin Film Transistors Using a Bilayer Channel Architecture

Abstract

We report here a bilayer metal oxide thin film transistor concept (bMO TFT) where the channel has the structure: dielectric/semiconducting indium oxide (In₂O₃) layer/semiconducting indium gallium oxide (IGO) layer. Both semiconducting layers are grown from solution via a low-temperature combustion process. The TFT mobilities of bottom-gate/top-contact bMO TFTs processed at <i>T</i> = 250 °C are ∼5tmex larger (∼2.6 cm²/(V s)) than those of single-layer IGO TFTs (∼0.5 cm²/(V s)), reaching values comparable to single-layer combustion-processed In₂O₃ TFTs (∼3.2 cm²/(V s)). More importantly, and unlike single-layer In₂O₃ TFTs, the threshold voltage of the bMO TFTs is ∼0.0 V, and the current on/off ratio is significantly enhanced to ∼1 × 10⁸ (vs ∼1 × 10⁴ for In₂O₃). The microstructure and morphology of the In₂O₃/IGO bilayers are analyzed by X-ray diffraction, atomic force microscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy, revealing the polycrystalline nature of the In₂O₃ layer and the amorphous nature of the IGO layer. This work demonstrates that solution-processed metal oxides can be implemented in bilayer TFT architectures with significantly enhanced performance