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.

turn changes the effective contrast between the alternating polymer and LC rich layers in the structure. This is a simple and flexible system by which photoresponsive photonic crystals can be fabricated in a single-step process. In addition to the one-dimensionally periodic systems such as those presented here, complex two-and three-dimensionally periodic HPDLC photonic materials could be fabricated [13] with the Azo-LC materials to make dynamic photonic crystals of any structure in a one-step process. Future studies will include fabricating novel photo-optic photonic structures, in addition to probing the ultimate response time of the system, as well as the effects of excitation intensity, wavelength, and azobenzene concentration. ExperimentalHolographic-polymer-dispersed liquid crystal structures containing azobenzene-derived liquid crystals were prepared from a standard prepolymer syrup containing 35 % E7, to which was added an additional 3.5 % BMAB. The preparation of a standard syrup can be found in [10] and [11], for example. The BMAB was synthesized according to [14], and can be commercially obtained from BEAMCo Inc, Winter Park, FL. Sample cells were prepared by placing a small amount of syrup to which a small amount of 8 lm glass spherical spacers were added on indium tin oxide (ITO) coated glass. The resulting cell contains approximately an 8±10 lm layer of photo sensitive syrup between two glass plates. Bragg reflection gratings were prepared using two counter propagating beams incident on the sample cell. This produced a one dimensionally periodic holographic structure with a grating vector perpendicular to the surface of the cell. The initial diffraction efficiency of these gratings was probed at normal incidence and ranged from 45 to 55 %. Control gratings prepared from an identical syrup without BMAB showed diffraction efficiencies of 50 to 55 %. Current studies in bulk have shown that 10 % BMAB in E7 is sufficient to induce an isothermal N±I transition at room temperature [15]. In order to minimize the attenuation of the triggering UV light through the thickness of the sample, it is desirable to use as low a concentration of Azo-LC as is sufficient to observe a complete, isothermal N±I transition. Thus approximately 3.5 % of the weight of the syrup in BMAB was added to the syrup, which constitutes roughly 10 % of the liquid crystal content. A convenient wavelength, 540 nm, was selected for holographic recording such that it did not overlap the cis absorption substantially, which provided for an accurate measurement of the diffraction efficiency.Once recorded, the reflection gratings are characterized in an apparatus which allowed for the introduction of both a UV laser beam (up to 80 mW cm ±2 of 365 nm from and Ar+ laser) and a doubled Nd:YVO 4 CW beam of 532 nm (up to 100 mW cm ±2 ) while the visible transmission spectrum and absorbance at 365 nm are simultaneously recorded. The UV beam was near the peak absorption of the trans conformer of the Azo-LC and produced a discernable change in color ...

We demonstrated micrometer-scale resolution X-ray imaging by using phase-separated scintillator fibers. Hexagonally well-aligned 680-nm-diameter GdAlO3(GAP):Ce3+ scintillator fibers surrounded with α-Al2O3 were fabricated from directionally solidified eutectics. The GAP:Ce3+ fibers convert X-rays to lights and emitted lights are confined and transported along the fiber direction by a total reflection mode. High-resolution X-ray image of a gold grating phantom with a 4 μm aperture, corresponding to a bundle of 12 fibers, was achieved even with a 150 -μm-thick scintillator. These scintillator fibers overcome resolution reduction caused by light scattering and almost reach the resolution limit of the material nature itself.

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 properties are very sensitive to the Zn:In ratio. The best TFT performances are obtained at Zn:In ∼60:40 at%, where the saturation mobility (μsat), subthreshold swing (S.S.), on–off current ratio (Ion/Ioff), and threshold voltage (Vth) are 26.5 cm2/V s, 0.24 V/dec., 1010, and +2 V, respectively. The TFT characteristics peak at this compositional ratio. Specifically, μsat, Ion/Ioff and Vth reach maximum, while S.S. reaches minimum at this ratio. The air stability of ZIO‐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. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)