The compositional dependence of sputter-deposited Zn - In - O (ZIO) film properties and the TFT performance were studied by means of a combinatorial technique. Both the characteristics of ZIO-TFTs and the ZIO film properdes are very sensitive to the Zn : In ratio. The best TFT performances are obtained at Zn:In ∼60:40 at%, where the saturation mobility (μ sat), subthreshold swing (S.S.), on-off current ratio (I on/I off), and threshold voltage (V th) are 26.5 cm 2/V s, 0.24 V/dec., 10 10, and +2 V, respectively. The TFT characteristics peak at this compositional ratio. Specifically, μ sat, I on/I off and V th reach maximum, while S.S. reaches minimum at this ratio. The air stability of ZIQ-TFTs was also examined for active channel layers with different Zn:In ratios, which clarified that the TFTs with high stability are obtained around the same composition ratio where the best characteristics are obtained. It was confirmed by X-ray diffraction and transmission electron microscopy that the ZIO films with this composition ratio have amorphous structure.
|ジャーナル||Physica Status Solidi (A) Applications and Materials Science|
|出版ステータス||出版済み - 8 1 2008|
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