Circuits using uniform TFTs based on amorphous In-Ga-Zn-O

High-performance and excellent-uniformity thin-film transistors (TFTs) having bottom-gate structures are fabricated using an amorphous indium-gallium-zinc-oxide (IGZO) film and an amorphous-silicon dioxide film as the channel layer and the gate insulator layer, respectively. All of the 94 TFTs fabricated with an area 1 cm(2) show almost identical transfer characteristics: the average saturation mobility is 14.6 cm(2)/(V-sec) with a small standard deviation of 0.11 cm(2)/(V-sec). A five-stage ring-oscillator composed of these TFTs operates at 410 kHz at an input voltage of 18 V. Pixel-driving circuits based on these TFTs are also fabricated with organic light-emitting diodes (OLED) which are monolithically integrated on the same substrate. It is demonstrated that light emission from the OLED cells can be switched and modulated by a 120-Hz ac signal input. Amorphous-IGZO-based TFTs are prominent candidates for building blocks of large-area OLED-display electronics.