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

TLDR

The study aims to explore amorphous oxide semiconductors as channel layers for high‑performance, flexible, and transparent thin‑film transistors, guided by chemical bonding and electronic structure considerations. The authors investigate the material properties of amorphous oxide semiconductors, focusing on their chemical bonding and electronic structure, to inform the design of flexible, transparent TFTs. Amorphous In–Ga–Zn–O films exhibit high Hall mobilities (>10 cm² V⁻¹ s⁻¹), tunable carrier concentrations, excellent chemical stability up to 500 °C, and enable flexible, transparent TFTs with normally‑off operation, on/off ratios ~10⁶, and field‑effect mobilities ~10 cm² V⁻¹ s⁻¹—outperforming amorphous Si:H and organic TFTs by an order of magnitude.

Abstract

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·V-1·s-1) and a good controllability of carrier concentration from <1015 to 1020 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 (∼106) and field-effect mobilities (∼10 cm2·V-1·s-1), which are higher by an order of magnitude than those of amorphous Si:H and organics TFTs.