Dielectric Properties of Solution-Processed ZrO2 for Thin-Film Transistors

Abstract

We have proposed an optimized ZrO2 dielectric layer via solution processing for use in amorphous oxide semiconductor (AOS) thin-film transistors (TFTs). The optimized conditions were 5 applied spin-coatings and an annealing temperature of 350 degrees C. These conditions were based on capacitance-voltage (C-V) characteristic measurements. When a gate bias stress of -10 V was applied to the ZrO2 films coated 5 times for 10 minutes, the flat-band voltage (V-FB) shifted by +1.553 V. The leakage current density was 5.18x10 (6) A/cm(2) at a gate voltage of -10 V. Furthermore, when the ZrO2 films deposited from a 0.2 M solution of ZrO2 were annealed at 350 degrees C for 2 h, a small difference in the C-V hysteresis curve of 20 mV was observed. The optimized ZrO2 film had a thickness of 139 nm, a capacitance in the accumulation region of 138.23 nF/cm(2) and a dielectric constant of 21.70. Based on these results, the fabricated IGZO/ZrO2 TFT showed a saturation mobility of 0.604 cm(2)/Vs, which is higher than that of IGZO/SiO2 TFTs.