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The BiFeO 3 (BFO) thin film was deposited by pulsed-laser deposition on SrRuO 3 (SRO)-buffered (111) SrTiO 3 (STO) substrate. X-ray diffraction pattern reveals a well-grown epitaxial BFO thin film. Atomic force microscopy study indicates that the BFO film is rather dense with a smooth surface. The ellipsometric spectra of the STO substrate, the SRO buffer layer, and the BFO thin film were measured, respectively, in the photon energy range 1.55 to 5.40 eV. Following the dielectric functions of STO and SRO, the ones of BFO described by the Lorentz model are received by fitting the spectra data to a five-medium optical model consisting of a semi-infinite STO substrate/SRO layer/BFO film/surface roughness/air ambient structure. The thickness and the optical constants of the BFO film are obtained. Then a direct bandgap is calculated at 2.68 eV, which is believed to be influenced by near-bandgap transitions. Compared to BFO films on other substrates, the dependence of the bandgap for the BFO thin film on in-plane compressive strain from epitaxial structure is received. Moreover, the bandgap and the transition revealed by the Lorentz model also provide a ground for the assessment of the bandgap for BFO single crystals.

Crystallographic and microstructural studies of BaTiO3 thin films grown on SrTiO3 by laser molecular beam epitaxy J. Vac. Sci. Technol. A 15, 275 (1997); 10.1116/1.580524 BaTiO3 thin films grown on SrTiO3 substrates by a molecular-beam-epitaxy method using oxygen radicals Epitaxial ultrathin films of BaTiO 3 were prepared using molecular beam epitaxy. For the substrate, ͑001͒-oriented SrTiO 3 single crystals were used. Controlling the growth conditions of these films as well as the semiconductor thin films, led to the successful growth of the BaTiO 3 films as single crystals, characterized by x-ray diffraction even in the ultrathin range. The ultrathin BaTiO 3 films are highly c-axis-oriented tetragonal phaselike bulk BaTiO 3 crystals. The tetragonality of the thin film crystals is much larger than bulk crystal's. We also measured the saturated polarization ( Ps͒ of the BaTiO 3 films at temperatures ranging from room temperature to 600°C. The results confirmed again that the films are ferroelectric tetragonal phase crystals. Moreover, they showed that the transition temperature for the ferroelectric-paraelectric phase transition of the films is higher than bulk crystal's.

There have been only a limited number of reports on solution-processed n-channel organic thin-film transistor (OTFT) devices with high levels of electrical performance, because the material design process for the n-type organic semiconductors are relatively difficult compared to p-type semiconductors, and further chemical modification of the functional groups are required. As a result, the development of soluble n-type organic semiconductors with high carrier mobilities has remained a challenge. Our work addresses this by introducing a novel molecular design to realize soluble n-type organic semiconductors with high electron mobilities, through the simple substitution of trifluoromethyl or trifluoromethoxy groups at meta-positions support sufficient solubility, creating suitable LUMO energy levels and high crystallinity. These newly designed benzobisthiadiazole (BBT)-based molecules showed electron mobilities as high as 0.61cm 2 V −1 s −1 in solution-processed OTFT devices. As a practical application in printed electronics, we demonstrated an organic complementary inverter circuit with OTFT devices using the developed soluble organic semiconductors. Due to their high solubility level and superior electrical properties compared to common para-derivatives, the utilization of meta-substituents is a new strategy for the design of soluble organic semiconductors in the field of OTFT device fabrication.

An x-ray absorption fine-structure (XAFS) spectroscopy beamline, BL01B1, was installed at a bending magnet source at SPring-8 and has been open to users since October 1997. It was designed for XAFS experiments covering a wide energy range. Position tables and automatical control programs were established to adjust the x-ray optics and achieve the designed performance of the beamline under each experimental condition. This has enabled conventional XAFS measurements to be made with a good data quality from 4.5 to 110 keV. Keywords: XAFS; high-energy; beamlines.143 radiation light will be reported elsewhere. The results show that the target specifications for the measured beam have almost been completely achieved except for sagittal focusing: a photon flux of 109-10 ~ phs/s with AE/E of <2x 104, a vertical beam size focused by a mirror of < 0.2 mm, and a ratio of the higher harmonics contaminant of < 10 .5 with mirrors.To achieve the designed performance of the beamline in a wide energy range, the beamline optics should be adjusted to the optimal position for each experiment. Because rearranging the monochromator and/or mirrors involves the realignment of many components, such rearranging can be done a few times per day. To achieve quick and easy adjustment, we prepared tables at the positions of the optical components and developed automatic control programs. This report gives an overview of the beamline status and some representative results highlighting the performance of BL01B 1.