One-Shadow-Mask Self-Assembled Ultralow-Voltage Coplanar Homojunction Thin-Film Transistors

A self-assembling diffraction method is developed for low-voltage coplanar homojunction thin-film transistor (TFT) fabrication. In this one-shadow-mask process, a channel layer can be simultaneously self-assembled between indium-tin-oxide (ITO) source/drain electrodes during magnetron sputtering deposition. When a microporous SiO₂-based solid electrolyte is used as the gate dielectric, full-depletion-mode ITO TFTs show an ultralow operation voltage of 1.5 V due to the large specific capacitance (4.44 μF/cm²). A small subthreshold swing of 0.12 V/decade and a large on/off ratio of 10⁶ are obtained. Our results demonstrate that such a simple one-mask self-assembling method is promising for low-cost TFT fabrication.