金並みの導電性と赤外透明性を有する高耐久酸化物薄膜

7.　むすび

本稿では，PdCoO₂やPtCoO₂に代表される金属性デラフォサイトについて，金並みの導電性，高い近赤外域の光透過率，巨大仕事関数，高耐久性という観点から紹介した。これらの物質は，酸化物でありながらAuに匹敵する高い面内電気伝導度を示す。また，極薄膜化によって近赤外透明電極として機能する可能性があり，近赤外領域の光デバイスに新しい選択肢を与える。

さらに，表面分極を利用することで，従来の単体金属電極では難しかった高仕事関数電極として機能しうる。金属性デラフォサイト薄膜はまだ研究の初期段階にあるが，スパッタ法による2インチウエハ成膜も実証され，光学やエレクトロニクス応用に向けた材料評価を進められる段階に入りつつある。本材料は，既存のITOや金属薄膜を単純に置き換えるものではなく，近赤外透過性，耐熱性，界面機能が同時に求められる領域で特に価値を発揮すると考えられる。

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■Highly Durable Oxide Thin Films with Gold-Like Conductivity and a Work Function Above 7eV
■Takayuki Harada
■National Institute for Materials Science Research Center for Materials Nanoarchitectonics, Principal Researcher