Low-temperature, nontoxic water-induced high-k zirconium oxide dielectrics for low-voltage, high-performance oxide thin-film transistors

Abstract

The fabrication of water-induced amorphous high-k zirconium oxide (ZrO_x) dielectrics has been proposed with the objective of achieving high performance and reducing costs for next generation displays. In this study, the as-prepared ZrO_x thin films were fabricated by a sequential process, including a UV-assisted photochemical treatment and a thermal annealing process at temperatures lower than 300 °C. It is observed that the leakage current density of ZrO_x thin films decreases, and the capacitance increases with increasing annealing temperatures. To verify the application possibilities of ZrO_x thin films as gate dielectrics in complementary metal-oxide semiconductor (CMOS) electronics, both n-type In₂O₃ and p-type NiO_x channel layers were integrated with ZrO_x dielectrics and their corresponding electrical performances were examined. The In₂O₃/ZrO_x thin film transistor (TFT) annealed at 250 °C exhibited a high electron mobility of 10.78 cm² V⁻¹ s⁻¹, a small subthreshold swing of 75 mV dec⁻¹, and a large on–off current ratio (I_on/I_off) of around 10⁶, respectively. Moreover, the p-type NiO_x/ZrO_x TFT exhibited an I_on/I_off of 10⁵ and a hole mobility of 4.8 cm² V⁻¹ s⁻¹. It is noted that both n- and p-channel oxide TFTs on ZrO_x could be operated at voltages lower than 4 V. The low-temperature fabrication process marks a great step towards the further development of low-cost, all-oxide CMOS electronics on flexible substrates.