Solution-Processed SrOx-Gated Oxide Thin-Film Transistors and Inverters

Abstract

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 SrOx 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 SrOx thin films were improved with increasing annealing temperature. The post-annealing at temperatures higher than 400 °C enables the SrOx 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 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/SrOx TFT exhibits high performance with an average field-effect mobility of 5.61 cm2 V−1 s−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/SrOx 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.