Amorphous Oxide Semiconductors for High-Performance Flexible Thin-Film Transistors

概要

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Recently, we have demonstrated the potential of amorphous oxide semiconductors (AOSs) for developing flexible thin-film transistors (TFTs). A material exploration of AOSs desired as the channel layer in TFTs is most important for developing high-performance devices. Here, we report our concept of material exploration for AOSs in high-performance flexible and transparent TFTs from the viewpoints of chemical bonding and electronic structure in oxide semiconductors. We find that amorphous In–Ga–Zn–O (a-IGZO) exhibits good carrier transport properties such as reasonably high Hall mobilities (${>}10$ cm2$\cdot$V-1$\cdot$s-1) and a good controllability of carrier concentration from ${<}10^{15}$ to $10^{20}$ cm-3. In addition, a-IGZO films have better chemical stabilities in ambient atmosphere and at temperatures up to 500 °C. The flexible and transparent TFT fabricated using a-IGZO channel layer at room temperature operated with excellent performances, such as normally-off characteristics, on/off current ratios (${\sim}10^{6}$) and field-effect mobilities (${\sim}10$ cm2$\cdot$V-1$\cdot$s-1), which are higher by an order of magnitude than those of amorphous Si:H and organics TFTs.
2006-05-30