The role of solution-processed high-κ gate dielectrics in electrical performance of oxide thin-film transistors

Abstract

We developed a simple and environmentally friendly spin-coating method for high-κ dielectrics (AlO_x, ZrO_x, YO_x and TiO_x). These materials were used as gate dielectrics for solution-processed nanocrystalline In₂O₃ or amorphous InZnO TFTs with a maximum processing temperature of 300 °C. The role of high-κ dielectrics in device performance was systematically studied. Among the high-κ dielectrics, the AlO_x-based devices showed the best performance with mobilities of 21.7 cm² V⁻¹ s⁻¹ in an In₂O₃ TFT and 11.6 cm² V⁻¹ s⁻¹ in an InZnO TFT with the on/off current ratio exceeding 10⁶. Furthermore, the devices exhibited ultra-low operating voltages (<3 V) and negligible hysteresis. A comprehensive study suggests that the high performance of the AlO_x-based devices could be attributed to the smooth dielectric/semiconductor interface and the low interface trap density besides its good insulating properties. Therefore, the solution-processed AlO_x can be used as a promising high-κ dielectric for low cost, low voltage, high-performance oxide electronic devices.