Solution-Processed SrO x -Gated Oxide Thin-Film Transistors and Inverters

In this paper, high-k strontium oxide (SrOx) dielectric thin films were fabricated using simple and low-cost solution process. The formation and properties of SrOxthin films annealed at various temperatures (400°C, 500°C, 600°C, and 700°C) were investigated using numbers of characterization techniques. The electrical analysis indicates that the insulating properties of SrOx thin films were improved with increasing annealing temperature. The post-annealing at temperatures higher than 400°C enables the SrOxthin film, exhibiting low-leakage current density of ~10-8A cm-2at 3 V and the areal capacitance larger than 350 nF cm-2at 20 Hz. To further explore the possible applications of solution-processed high-k SrOx thin films for thin-film transistors (TFTs), the indium oxide (In2O3) TFTs based on SrOx thin films were integrated for testing. The optimized In2O3/SrOxTFT exhibits high performance with an average field-effect mobility of 5.61 cm2V-1s-1, a small subthreshold swing of 110 mV dec-1, and a large on/off current ratio of 107. To demonstrate the potential of In2O3/SrOxTFT toward more complex logic applications, the unipolar inverter was further constructed and exhibited a high gain of 9.7. Importantly, all these device parameters were obtained at an ultralow operating voltage of 3 V, which represents a step toward portable, battery-driven, and low-power consumption electronics and circuits.