Solution-processed high-k magnesium oxide dielectrics for low-voltage oxide thin-film transistors

Solution-processed metal-oxide thin films with high dielectric constants (k) have been extensively studied for low-cost and high-performance thin-film transistors (TFTs). In this report, MgO dielectric films were fabricated using the spin-coating method. The MgO dielectric films annealed at various temperatures (300, 400, 500, and 600 °C) were characterized by using thermogravimetric analysis, optical spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and atomic-force microscopy. The electrical measurements indicate that the insulating properties of MgO thin films are improved with an increase in annealing temperature. In order to clarify the potential application of MgO thin films as gate dielectrics in TFTs, solution-derived In₂O₃ channel layers were separately fabricated on various MgO dielectric layers. The optimized In₂O₃/MgO TFT exhibited an electron mobility of 5.48 cm²/V s, an on/off current ratio of 10⁷, and a subthreshold swing of 0.33 V/dec at a low operation voltage of 6 V. This work represents a great step toward the development of portable and low-power consumption electronics.