Water-Derived All-Oxide Thin-Film Transistors With ZrAlO x Gate Dielectrics and Exploration in Digital Circuits

Abstract

In this article, novel ZrAlO x gate dielectric films were fabricated by a simple, low-cost, and environmentally, eco-friendly, fully water-induced (WI) method for the first time. The microstructure, optical transmittance, surface topography, chemical compositions, and electrical properties of WI ZrAlO x films annealed at 300 °C–600 °C were characterized. Experimental results demonstrated that the 500 °C-annealed WI ZrAlO x film has a good amorphous state, high transmittance, very smooth surface morphology, large area capacitance, and low leakage current density. In order to verify the feasibility of the 500 °C-annealed ZrAlO x film as a dielectric in thin-film transistor (TFT) devices, In2O3/ZrAlO x TFTs were successfully fabricated. The optimized 270 °C-annealed TFT devices have shown excellent electrical characteristics at an extremely low operating voltage of 3 V, including a high $\mu _{{\text {FE}}}$ of 10.14 cm2V−1S−1, a high ${I}_{{\text {on}}}/{I}_{{\text {off}}}$ of ~ 106, a small subthreshold slope (SS) (100 mV dec−1), a low ${V}_{{\text {TH}}}$ (0.36 V), and a small ${N}_{S}^{{\text {max}}}$ ( $2.15\times {10}^{{12}}$ cm−2), respectively. To further explore the potential application of In2O3/ZrAlO x TFTs in digital circuits, a resistor-loaded inverter has been constructed and presented good voltage transfer characteristics and high voltage gain. In addition, the dynamic behavior with full swing characteristics has been obtained at a low ${V}_{{\text {DD}}}$ of 2 V. These excellent parameters show their great potential for application in low cost, highly transparent, portable, and low-power consumption electronics.