Spray-Pyrolyzed High-k Zirconium-Aluminum-Oxide Dielectric for High Performance Metal-Oxide Thin-Film Transistors for Low Power Displays

A high-k, zirconium-aluminum-oxide (ZAO) gate insulator (GI) using low-cost spray pyrolysis technique for large area and low power electronics is demonstrated. The high-quality spray-pyrolyzed ZAO GI is obtained with subsequent oxidation by eco-friendly Ar/O-2 plasma treatment. Analyses reveal that only one cycle Ar/O-2 plasma treatment significantly enhances the thin-film and dielectric properties of ZAO, exhibiting improved mass density (4.16 g cm(-3)), smooth surface roughness (0.32 nm), low leakage current density (2.26 x 10(-6) A cm(-2)), high breakdown electric field (5.15 MV cm(-1)), and negligible frequency-dependent capacitance. Hysteresis free, amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) with ZAO GI exhibit a field-effect mobility of 15.04 cm(2) V-1 s(-1), threshold voltage of 1.46 V, subthreshold swing of 115 mV dec(-1), I-ON/I-OFF ratio of 7.54 x 10(8), and negligible positive bias stress. The highly reliable a-IGZO TFTs performances are achieved due to the significant reduction of oxygen-related defects at the dielectric/semiconductor interface. The TFT inverter and an eleven-stage ring oscillator have been demonstrated with ZAO/a-IGZO TFTs, exhibiting a high voltage gain of 58, oscillation frequency of 2.43 MHz, and signal propagation delay of 18.7 ns at a supply voltage of 6 V, confirming the benefit of spray-pyrolyzed high-k ZAO dielectric for low power displays.

Automated summary

A high-k ZAO gate insulator prepared by spray pyrolysis technique with subsequent Ar/O-2 plasma treatment shows significantly improved thin-film and dielectric properties, leading to enhanced performance of a-IGZO thin-film transistors. The ZAO/a-IGZO TFTs exhibit high reliability and performance, making them suitable for low power displays.