Enhanced Electrical Performance and Bias Stability of a-IGZO Thin-Film Transistor by Ultrasonicated Pre-annealing

Abstract

Vacuum-processed oxide semiconductors have enabled incredible recent advances in the scientific research of metal oxide thin-film transistors (TFTs) and their introduction in commercial displays. Developing metal oxide transistors with low processing temperatures, on the other hand, remains a challenge. Metal oxide transistors are commonly produced at high processing temperatures (over 500°C) and have a high working voltage (30~50 V). Here, we introduce amorphous indium-gallium-zinc-oxide (a-IGZO) TFTs that show enhanced electrical characteristics, environmental stability, and switching behavior, prepared using ultrasonicated pre-annealing. Before post-annealing, the ultrasonication treatment was given at 40 kHz for 20 minutes. The improved electrical characteristics of this ultrasonicated a-IGZO TFTs were: 10.78 cm²/Vs; 1.2×10⁷ on/off current ratio. The a-IGZO TFTs with ultrasonicated pre-annealing were also extremely stable under a variety of stresses. For an ultrasonicated a-IGZO TFT, the threshold voltage (<i>Vth</i>) shifted by +0.82 V in a positive bias stress test and -0.30 V in a negative bias stress test. This means that the sonication treatment improves both electrical and surface morphological qualities, while also lowering faults by eliminating contaminants from the a-IGZO channel layer's surface and preventing atomic rearrangement. Furthermore, the dynamic response characteristics were measured according to frequency. A dynamic inverter test was carried out at 1 kHz frequency, with the load resistance of the circuit set to 10 MW and the drain supply voltage set to 5 V (<i>VDD</i>).