ABSTRACT
References ..................................................................................................................................... 525
Amorphous oxide semiconductor (AOS) is an alternative of crystalline oxide semiconductor and now expected to be most promising for channel materials of thin-Œlm transistors (TFTs) in next-generation ·at-panel displays (FPDs) such as active-matrix (AM) fast/ jumbo-size/ultrahigh-resolution liquid-crystal displays (LCDs), organic light-emitting diode displays (OLEDs), electronic papers (e-papers), and ·exible large-area electronic devices. Since the Œrst demonstration of an AOS TFT using an amorphous In-Ga-Zn-O (a-IGZO) channel [1], many chemical compositions have been proposed to date; however, a-IGZO has been studied most intensively and its mass production started in March, 2012 [2,3]. As will be explained later on, AOSs have superior properties to crystalline semiconductors such as ZnO for large-area microelectronics devices (giant microelectronics) because they exhibit large carrier mobilities >10 cm2 (V s)−1 even if these are fabricated at room temperature (RT); therefore, AOS TFTs and their devices are applicable to ·exible devices fabricated on organic plastic substrates and these devices have much better performances than those fabricated using conventional semiconductors such as hydrogenated amorphous silicon (a-Si:H) and organic semiconductors (Figure 13.1). Further, AOS TFTs are oxides of metal cations with closed-shell electronic conŒgurations and have large bandgaps >3.0 eV, which enable to develop completely transparent electronic circuits. In this chapter, we review brief history, fundamental properties, TFT technology, and device
applications of AOSs in particular for a-IGZO. Here, we recommend some reference papers and books for helping know more details [4-13].
