Thin-film transistors (TFTs) were fabricated using amorphous indium gallium zinc oxide (a-IGZO) channels by rf-magnetron sputtering at room temperature. The conductivity of the a-IGZO films was controlled from ∼10−3to10−6Scm−1 by varying the mixing ratio of sputtering gases, O2∕(O2+Ar), from ∼3.1% to 3.7%. The top-gate-type TFTs operated in n-type enhancement mode with a field-effect mobility of 12cm2V−1s−1, an on-off current ratio of ∼108, and a subthreshold gate voltage swing of 0.2Vdecade−1. It is demonstrated that a-IGZO is an appropriate semiconductor material to produce high-mobility TFTs at low temperatures applicable to flexible substrates by a production-compatible means.
A combinatorial approach was applied to thin-film transistors (TFTs) using amorphous In–Ga–Zn–O semiconductor channels. A large number of TFTs, having n-type channels with different chemical compositions, were fabricated simultaneously on a substrate. A systematic relation was clarified among the compositional ratio of In:Ga:Zn, oxygen partial pressure in film deposition atmosphere, and TFT characteristics. The results provide an experimental basis to understand the roles of each metallic element in the In–Ga–Zn–O system. This information leads to a guideline to tune the metallic compositions for required TFT specifications.
Anodic alumina films are known to have perpendicular holes normal to the film surface. This character is favorable to perpendicular magnetic recording and patterned media. L10-ordered CoPt columns are filled into anodic alumina nanoholes by an electrodeposition method and a subsequent thermal annealing process. Two kinds of metal (W and Pt) were used as underlayers at the bottom of nanoholes, which acts as electrode layer for electrodeposition. We show that while the embedded L10-ordered CoPt columns have random c-axis orientations for W underlayer samples, the c-axis orientation can be controlled by using the underlayer with Pt(001) surface. This orientation controlled sample has a perpendicular anisotropy with Hc=7.4 kOe, and Mr/Ms=0.96. This approach has the potential to become one of the important methods for the fabrication of recording media with ultrahigh areal density.
We demonstrate a single shot two-dimensional grating-based X-ray phase-contrast imaging using a synchrotron radiation source. A checkerboard designed phase grating for π phase modulation at 17 keV and 35 keV, and a lattice-shaped amplitude grating with a high aspect ratio to shield X-rays up to 35 keV were fabricated. A Fourier analysis of Moiré fringe generated by the gratings was introduced to obtain the two-dimensional differential phase-contrast image with a single exposure. The results show that soft tissues and cartilages of a chicken wing sample are clearly seen with differential phase variation in two-dimensional directions. Using this method not only the whole of an object but also only an inner part of the object can be imaged.
Carbon nanotubes (CNTs), standing perpendicularly to a substrate with an electrode, were fabricated by thermal catalytic decomposition of ethylene from Co particles electrochemically embedded at the bottom of anodic alumina nanoholes. The thermal durability of the alumina nanoholes for the CNTs growth process was achieved by using Nb as an underlying electrode. The CNTs were electrically connected to the electrode through the conductive paths, which were formed at the bottom of alumina nanoholes by Nb ion migration from the underlying electrode during anodization.
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