UV-Cured Hafnium Oxide-Based Gate Dielectrics for Low-Voltage Organic and Amorphous Oxide Thin-Film Transistors

In this study, we have fabricated hafnium oxide dielectrics for low-voltage organic and amorphous oxide thin-film transistors (TFTs) via a facile low-temperature solution method and investigated the electrical properties of these dielectrics. Hafnium oxide dielectric films can be easily fabricated by a sol-gel solution method and ultraviolet (UV) curing at room temperature. In addition, the surface energy of hafnium oxide films can be easily modified by using phosphonic-acid-based self-assembled monolayers. This modification makes these films compatible with organic semiconductors fabrication methods. These novel dielectrics exhibit excellent insulating properties (leakage current densities of <10^-6 A/cm² at 2 V), high capacitances (up to 690 nF/cm²), and smooth surfaces (root-mean-square roughness <0.5 nm). Consequently, hafnium oxide-based dielectrics can be integrated into both pentacene-based and indium oxide-based TFTs, functioning at relatively low voltages (<±3 V) to achieve good performance (hole mobility: 0.31 cm²/V · s, electron mobility: 1.54 cm²/V · s, and on/off current ratios: >10⁵).