Solution-processed hafnium oxide dielectric thin films for thin-film transistors applications

Abstract Hafnium oxide (HfO x ) dielectric thin films were fabricated on heavily-doped silicon (100) substrates by a solution process. The precursor solution was prepared by dissolving HfCl 4 in ethanol. The annealing effects on the microstructural and electrical properties of HfO x thin films were studied. The HfO x thin film annealed at 500 °C exhibited the best insulating performance with a current density of 1×10 −9 A/cm 2 at an electric field of 4.5 MV/cm. In order to demonstrate the possible application of HfO x thin films in thin-film transistors (TFTs), the indium-zinc oxide (IZO) channel layer was fabricated by magnetron sputtering at room temperature. The IZO TFT based on 500 °C-annealed HfO x can be operated under an operation voltage of 5 V, with a high field-effect mobility of 36.9 cm 2 /V s, a threshold voltage of 1.8 V, a subthreshold swing of 0.38 V/dec, and an on/off current ratio of 10 9 . The results demonstrate that HfO x thin film prepared by the solution process is a promising gate dielectric for high-performance oxide electronic devices.