Normally-off top-gate self-aligned field-effect transistor using crystal InOx with field-effect mobility of around 100 cm2/vs

In this study, we designed and fabricated a crystal InO_x (crystal IO)-based field-effect transistor (FET) on a 3.5th generation glass (600 mm × 720 mm) substrate line. The FET exhibits high field-effect mobility exceeding 90 cm²/Vs, an on-state current higher than that of a low-temperature polysilicon (LTPS)-based FET, normally-off characteristics, an extremely low off-state current, a high breakdown voltage, and high reliability. The synthesized crystal IO is less susceptible to grain boundary scattering and exhibits a small variation in grain size on the substrate plane. The crystal IO-based FET exhibits a small variation in electrical characteristics. Combining our organic light-emitting diode (OLED) patterning technology with a display backplane based on crystal IO, we obtained an 8.3-in. 8K4K OLED display with high luminance and low power consumption. These results demonstrate that crystal IO can replace LTPS and low-temperature polycrystalline oxide, which have been mainly used in the backplanes of small- and medium-sized displays, and that backplanes of displays of all sizes can be completely oxide based.