Metal-oxide thin-film transistors (TFTs) are promising for next-generation display backplanes and large-area electronics, while single-channel oxide TFTs often suffer from trade-offs among mobility, leakage current, and switching behavior. Here, an In₂O₃/SnO₂ dual-channel TFT was fabricated by magnetron sputtering to combine the high electron transport capability of In₂O₃ with the leakage-suppression characteristics of SnO₂. Compared with single-layer In₂O₃, single-layer SnO₂, and reverse-stacked SnO₂/In₂O₃ devices, the optimized In₂O₃/SnO₂ TFT exhibits improved overall performance, with a linear mobility of 19.15 cm²/Vs, a subthreshold swing of 0.86 V/dec, an on/off current ratio of 3.58 × 10⁶ and an optimized threshold voltage. The mobility is approximately 2.2 times higher than that of the single-layer In₂O₃ TFT, accompanied by obviously enhanced positive and negative stress stabilities. Furthermore, structural, chemical and optical analyses indicate that the enhanced performance can be attributed to the smooth heterointerface, favorable band alignment, and interfacial carrier redistribution between In₂O₃ and SnO₂. The superior performance highlights the potential of the In₂O₃/SnO₂ bilayer architecture for high-performance display-backplane switching and other large-area oxide-electronics applications.

SnO₂ exhibits low cost, high electron mobility and good optical transparency, making it a promising candidate for the active layer of indium-free oxide thin-film transistors (TFTs). However, its film qualities are highly sensitive to deposition conditions. In this work, SnO₂ thin films and TFTs were fabricated by radio-frequency magnetron sputtering under different substrate biases (0 V, −70 V and −110 V) to investigate the effects of substrate bias on film structure, defect state, interface quality and device performance. With increasing substrate bias magnitude, the film crystallinity improved, the relative area fraction of the defect-related O 1s component decreased from 31% to 19%, while the surface roughness increased, continuously. At a substrate bias of −70 V, the device exhibited relatively optimal overall performance, with a linear mobility (μ_lin) of 3.7 cm²/Vs, a subthreshold swing (SS) of 0.61 V/dec, and a threshold-voltage shift (ΔV_th) of 6.0 V after 3600 s of positive bias stress. These results indicate that an appropriate substrate bias can achieve a balance between crystalline quality and interface condition, thereby improving the performance of SnO₂ TFTs.