ABSTRACT
This chapter reviews fundamental properties, Thin-film-transistor (TFT) technology, and device applications of amorphous oxide semiconductors (AOSs) in particular for amorphous In-Ga-Zn-O. Amorphous semiconductors have outstanding advantages in device fabrication processes over crystalline semiconductors. Ionic AOSs have several common properties, which are not seen in conventional amorphous semiconductors. TFTs are fundamental building blocks for large-area microelectronics such as flat-panel displays (FPDs) and system-on-glass/panel. AOS TFTs have a large process allowance due to their unique annealing behaviors. A key technical issue for commercialization is long-term instability. In conventional color AM e-papers and displays, a color filter array is formed on a front plane and a TFT array on a back plane. Another interesting application is a transparent electronic device. For mass production of FPDs, large-area fabrication techniques are necessary to be developed. Another technical challenge in oxide TFTs is to realize complementary circuits only by oxide TFTs because CMOS circuits can produce very low-power consumption devices.
