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

In this paper, high-k strontium oxide (SrO x ) dielectric thin films were fabricated using simple and low-cost solution process. The formation and properties of SrO x thin 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 SrO x thin films were improved with increasing annealing temperature. The post-annealing at temperatures higher than 400 °C enables the SrO x thin film, exhibiting low-leakage current density of ~10 −8 A cm −2 at 3 V and the areal capacitance larger than 350 nF cm −2 at 20 Hz. To further explore the possible applications of solution-processed high-k SrO x thin films for thin-film transistors (TFTs), the indium oxide (In 2 O 3 ) TFTs based on SrO x thin films were integrated for testing. The optimized In 2 O 3 /SrO x TFT exhibits high performance with an average field-effect mobility of 5.61 cm 2 V −1 s −1 , a small subthreshold swing of 110 mV dec −1 , and a large on/off current ratio of 10 7 . To demonstrate the potential of In 2 O 3 /SrO x TFT 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.