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L10-ordered CoPt with a large coercivity (H c) of 13 kOe was demonstrated on Si/SiO2 substrates by hydrogen annealing. Equiatomic 11.2 nm thick (Co/Pt)4 multilayer thin films were fabricated by electron-beam evaporation and were annealed at 500 °C–900 °C for 10–90 min under an Ar/H2 mixed gas atmosphere. The annealing temperature and time dependences of the crystal structures, magnetic properties, and surface morphologies of the films were systematically analyzed based on the experimental results obtained from grazing incidence X-ray diffraction (GI-XRD), vibrating sample magnetometer, and scanning electron microscope, respectively. Hydrogen annealing effectively promoted the out-of-plane c-axis orientation of L10-ordered CoPt compared to the vacuum annealing according to the GI-XRD patterns. A maximum H c of 13.3 kOe was obtained in L10-ordered CoPt with angular-outlined isolated grains by hydrogen annealing at 800 °C for 60 min, where the c-axis of L10-ordered CoPt was randomly distributed.

We evaluated an estimation ability of shifts of therapeutic carbon-ion beams owing to cavities in a polyethylene target by measuring prompt X-rays emitted from beam trajectories. Carbon-12 beams having the energy of 241.5 MeV/u were irradiated on a polyethylene target. The target had a square-prism-shaped cavity in it. The thickness of the cavity was changed from 3.0 to 0.0 cm with 0.3-cm steps. For each setup of the cavity, 7.5 × 10^10 carbon ions were irradiated. A pinhole-type X-ray camera was placed beside the target and utilized to acquire the beam images. The beam trajectory and a gap on the trajectory clearly appeared in the acquired images. The actual beam shifts well coincided with the estimated beam shifts from the acquired images. The maximum fluctuation of the estimated shifts was approximately 0.2 cm. It was confirmed that the internal cavity can be imaged and the range can be accurately evaluated.

Non-destructive monitoring of radioactivities derived from radioactive tracers at multiple points in plant stems can be used to evaluate the velocity of element transport in living plants. In this study, we calculated absorption-efficiency distributions for several detector geometries to determine appropriate shapes for non-destructive monitoring of radioactivities in the stem. The efficiency distributions were calculated by Monte Carlo simulations, and the flatnesses and spatial resolutions were evaluated. It was found that the placement of four detectors around the stem could limit the percentage of standard deviation to the mean of the pixel values to less than 5%. We could determine a compact detector geometry with a spatial resolution of 1.35 cm using four small detectors. The detection efficiencies were 0.014, 0.0030 and 0.000 63 cm at the initial gamma-ray energies of 0.5, 1 and 2 MeV, which is sufficiently applicable to detect 10 kBq cm−1 of radioactivity.

Non-destructive monitoring of radioactivities derived from radioactive tracers at multiple points in plant stems can be used to evaluate the velocity of element transport in living plants. In this study, we calculated absorption-efficiency distributions for several detector geometries to determine appropriate shapes for non-destructive monitoring of radioactivities in the stem. The efficiency distributions were calculated by Monte Carlo simulations, and the flatnesses and spatial resolutions were evaluated. It was found that the placement of four detectors around the stem could limit the percentage of standard deviation to the mean of the pixel values to less than 5%. We could determine a compact detector geometry with the spatial resolution of 1.35 cm using four small detectors. The detection efficiencies were 0.014, 0.0030 and 0.00063 cm at the initial gamma-ray energies of 0.5, 1 and 2 MeV, which is sufficiently applicable to detect 10 kBq/cm of radioactivity.

Radioisotope tracer imaging is useful for studying plant physiological phenomena. In this study, we developed an autoradiography system with phosphor powder (ZnS:Ag),‘ Live-autoradiography ’, for imaging radioisotope dynamics in a living plant. This system visualizes the element migration and accumulation in intact plants contin- uously under a light environment. An imaging test was performed on point sources of 137Cs, with a radioactivity of 10–100 kBq of being observed; this indicates satisfactory system linearity between the image intensity and the radioactivity of 137Cs. Moreover, dynamics imaging of 137Cs was performed on an intact soybean plant for four days. The serial images indicated 137Cs accumulation in the node, vein, and growing point of the plant. The developed system can be used for studying plant physiological phenomena and can be employed for quantitative measurement of radionuclides.

We evaluated an estimation ability of shifts of therapeutic carbon-ion beams owing to cavities in a polyethylene target by measuring prompt X-rays emitted from beam trajectories. Carbon-12 beams having the energy of 241.5 MeV u−1 were irradiated on a polyethylene target. The target had a square-prism-shaped cavity in it. The thickness of the cavity was changed from 3.0 to 0.0 cm with 0.3 cm steps. For each setup of the cavity, 7.5 × 1010 carbon ions were irradiated. A pinhole-type X-ray camera was placed beside the target and utilized to acquire the beam images. The beam trajectory and a gap on the trajectory clearly appeared in the acquired images. The actual beam shifts well coincided with the estimated beam shifts from the acquired images. The maximum fluctuation of the estimated shifts was approximately 0.2 cm. It was confirmed that the internal cavity can be imaged and the range can be accurately evaluated.

L12-ordered CoPt3 and L10-ordered CoPt are formed in electron-beam-deposited (Co/Pt)4 multilayer thin films with and without a Ti underlayer, respectively, on Si/SiO2 substrates by rapid thermal annealing. The crystal structures, magnetic properties, and surface morphologies of the films are investigated by grazing incidence X-ray diffraction (GI-XRD), vibrating sample magnetometer (VSM), and scanning electron microscope (SEM), respectively. In the film without a Ti underlayer, L10-ordered CoPt with an isolated round grain structure is confirmed, showing an in-plane coercivity of 2.7 kOe. In contrast, in the film with a Ti underlayer, L12-ordered CoPt3 is confirmed together with Co-rich A1-disordered CoPt, showing an in-plane coercivity of 500 Oe, which exhibits an angular-outlined continuous film structure. The three sets of experimental results from GI-XRD, VSM, and SEM coincide well with each other.

A simulation study on reduction of a background (BG) component for an imaging method of therapeutic proton beams by measuring secondary electron bremsstrahlung (SEB) component was performed using the Monte Carlo method. We simulated the images obtained by measuring the SEB and the BG component using a parallel-hole-type X-ray camera placed close to an irradiation target. We found that reduction of the BG component was possible by utilizing veto counters placed close to the imaging detector of the X-ray camera. The ratio of the BG component to the sum of the SEB and BG components was able to be reduced from 73% to approximately 20%.

It is expected that the off-state leakage current of MOSFETs can be reduced by employing vertical body channel MOSFETs (V-MOSFETs). However, in fabricating these devices, the structure of the Si pillars sometimes cannot be maintained during oxidation, since Si atoms sometimes disappear from the Si/oxide interface (Si missing). Thus, in this study, we used first-principles calculations based on the density functional theory, and investigated the Si emission behavior at the various interfaces on the basis of the Si emission model including its atomistic structure and dependence on Si crystal orientation. The results show that the order in which Si atoms are more likely to be emitted during thermal oxidation is (111) > (110) > (310) > (100). Moreover, the emission of Si atoms is enhanced as the compressive strain increases. Therefore, the emission of Si atoms occurs more easily in V-MOSFETs than in planar MOSFETs. To reduce Si missing in V-MOSFETs, oxidation processes that induce less strain, such as wet or pyrogenic oxidation, are necessary.

Thin-film transistors (TFTs) were fabricated on polycrystalline silicon (poly-Si) films formed by position-controlled large-grain growth technology using an excimer laser. The field-effect mobility, on-off transition slope, and threshold voltage were 914 cm2 V-1 s-1, 93 mV/decade, and 0.58 V for the n-channel device, and 254 cm2 V-1 s-1, 122 mV/decade, and -0.43 V for the p-channel device, respectively. These values indicate that TFTs had an ultrahigh performance comparable to that of {100}-oriented crystal-silicon metal–oxide–semiconductor (MOS) transistors. Furthermore, their effective mobilities had the same effective field and temperature dependences as those of MOS transistors, indicating that electrons and holes were predominantly scattered not by random grain boundaries or defects in the Si film, but by phonons at the SiO2–Si interface, similarly to those of crystal-silicon MOS transistors. These attractive results were obtained as a result of the fact that the TFT channel region was made up of nearly {100}-oriented single grains.

The dependences of field-effect mobility, threshold voltage, and subthreshold slope on temperature for low-temperature polycrystalline silicon (LTPS) thin film transistors (TFTs) with large grains were investigated. It was shown that the temperature dependences of field-effect mobility and threshold voltage are affected by the temperature dependence of negatively charged grain-boundary-related interface traps near the surface of polycrystalline silicon, which is explained by considering that the degree of band bending at the surface when gate voltage is equal to threshold voltage decreases with increasing temperature. It was also shown that the behavior of a subthreshold slope can be explained using a term of the grain-boundary-related interface traps near the surface. Moreover, the effects of grain boundaries on hot-carrier generation and hot-carrier-induced degradation were investigated separately, and both processes were experimentally found to be affected by the grain boundaries.

Polycrystalline silicon (poly-Si) complementary metal–oxide–semiconductor (CMOS) circuits have been fabricated by using an advanced excimer-laser annealing method and a plasma-oxidation method. The 1-µm-long thin-film transistors (TFTs) were fabricated on arrays of laterally grown long and narrow grains, so that the majority of carriers were free from scattering at grain boundaries during propagation through the channel. The propagation delay time measured by a 21-stage ring oscillator was 175 ps and a power-delay product of 9×10-13 J/gate was obtained at a supply voltage of 3.3 V. The obtained propagation delay time was almost the same as those of bulk Si devices having the same gate length. Furthermore, we expect that 1-µm-long CMOS TFT circuits on glass will have a performance superior to that of 1-µm-long bulk Si devices when the short channel effect and threshold voltage fluctuation are controlled well.

Excellent characteristics of polycrystalline silicon (poly-Si) thin-film transistors (TFTs) with long and narrow grains aligned one-dimension have been experimentally clarified for the first time. The field effect mobility and on-off transition slope of n-channel and p-channel devices were as high as 685 cm2 V-1 s-1 and 190 mV/decade and 145 cm2 V-1 s-1 and 104 mV/decade, respectively. Fluctuations of characteristics were considerably reduced by widening the channel, and uniform characteristics were observed when there were approximately twenty long grains within the channel. These results were obtained when the TFT channel was formed within a region free from grain boundaries formed by head-on collision of laterally growing grains and seeds used to initiate lateral grain growth. Material properties are discussed from the viewpoint of device characteristics.

In this paper, we report the first measurement of the time-integrated spatial coherence of the Ni-like Ag X-ray laser at 13.9 nm pumped by a 1.5 ps, 20 J Nd glass laser, in which the transient collisional excitation (TCE) pumping scheme is realized. The time-integrated complex coherence factor (CCF) of the X-ray laser has been determined from partially coherent diffraction patterns of a multislit array placed 1 m away from the X-ray laser source. The transverse coherence lengths in the directions horizontal and vertical to the Ag target surface are estimated respectively to be within 110 µm to 140 µm at a position 1 m from the X-ray laser source. We tried to explain the profile of the CCF with a quasi-monochromatic incoherent source model with various profiles.

We precisely measured the electrical mobilities of C60 negative ions (1.0 nm in outer diameter) using a differential mobility analyzer in helium, neon, argon, and krypton at pressures ranging from 1.07×104 to 4.40×104 Pa. The measured inverse mobilities were larger than those calculated from the hard-sphere collision model. We proposed a formula describing the relation between the electrical mobilities and the diameter of C60 ions in such noble gases, which compensates for the deviation from the hard-sphere collision model.

We have demonstrated a high gain neon-like argon ion X-ray laser using a gas puff target. The elongated X-ray laser plasma column was produced by irradiating the gas puff target with line-focused double picosecond laser pulses with a total energy of 9 J in a travelling-wave excitation scheme. Strong lasing was observed, and a high gain coefficient of 18.7 cm-1 and a narrow beam divergence of less than 3.7 mrad were measured on the transient collisionally excited 3p1S0-3s1P1 transition for neon-like argon at 46.9 nm with targets up to 0.45 cm long.

A grazing incidence reflection-type soft X-ray microscope, using a Fresnel zone plate and a soft X-ray laser with wavelength 13.9 nm and pulse width 7 ps, was developed. Submicron size groove structures made on a Pt film were clearly captured at a single shot exposure, with spatial resolution of about 360 nm. A wide field view of 100 µm square was secured under the Kohler illumination. This microscope also had a large depth of focus of more than 100 µm and was proven to have a sufficient performance for observing surface morphological changes.

To develop materials for achieving local hyperthermia, we investigate the heating of various ferrite and metal powders by applying an external AC magnetic field. In comparison with magnetite powder, which has often been used in previous experiments, Mg-ferrite powder is more applicable for achieving local hyperthermia.

We have developed a soft-X-ray laser interferometer based on a double Lloyd's mirror and obtained a single-shot interferogram using a 7-ps-duration pulse at a wavelength of 13.9 nm. Micrometer grooves with a depth of 5 nm were successfully reconstructed from the interferogram. The lateral and depth resolutions were estimated to be 1.5 µm and better than 1 nm, respectively. This interferometer will be an attractive diagnostic device for observing transiently changing nanometer-scale deviations on solid surfaces.

We demonstrate the potential of a hydrothermal method-grown ZnO as a high-spatial resolution imaging device for in-situ soft X-ray laser diagnostics by characterizing the exciton emission patterns. By plotting the emission pattern radii at each position, we estimated the evolution of the beam radius around the focal point. The beam profile of the Ni-like Ag ion plasma laser was estimated from the waist radii as 29 and 21 µm, the divergence angle as 7.2 and 11 mrad and the M 2 factor as 47 and 50 in the horizontal- and vertical-axis, respectively. Spatial resolution of the magnifier was estimated to be 6 µm and is expected to improve by optimizing the optics of the magnifier and using a telescope. Our results would enhance the use of ZnO as an imaging device that would play a crucial role in the development and application of soft X-ray light sources.

It was observed that the bias stressing of low-temperature polycrystalline silicon thin-film transistors (LTPS-TFTs) gave rise to anomalous instabilities in device characteristics, such as negative threshold voltage shifts in both n- and p-channel TFTs, and the recovery of the shift even under stress. From detailed investigations of these phenomena, it was found that the instability is caused by self-heating due to the drain current, and is related to hydrogen and/or water diffusing into the gate oxide from the interlayer dielectric. It is considered that these phenomena will become more significant in future scaled TFTs; therefore, it is important that low-temperature processes taking account of water-related components are carefully introduced.

The characteristics of thin-film transistors (TFTs) fabricated on pseudo-single-crystal (PSX)-Si thin films were examined. The variations of mobility were more than the theoretical values derived from the crystallographic orientation dependence of a bulk Si metal–oxide–semiconductor (MOS) transistor. To clarify the origin of this discrepancy, the relationships between the TFT characteristics and the crystallographic orientation of Si films in the channel region were investigated by using an electron backscattering pattern (EBSP) method. It was found that the surface orientation dependence for the PSX-Si TFT was different from that for a bulk Si MOS transistor, especially for the p-channel mode. A group of TFTs having a nearly {100}-oriented nucleus had a mobility close to those of simultaneously processed silicon-on-insulator (SOI) devices in the p-channel mode as well as in the n-channel mode. In contrast, a group of TFTs having a nearly {110}-oriented nucleus had a low and widely scattered mobility. The reason for these results is that twin boundaries with dislocations are easily generated in a grain grown from a {110}-oriented nucleus in order to compensate for the difference of the growth rates in different directions.

A tabletop ultra-bright, debris-free femtosecond-laser-driven cluster-based plasma soft X-ray source, which emits more than 1012 photons/(sr·pulse) in the spectral range 1–10 nm within a 4π sr solid angle was developed. Using such source in combination with a high dynamic range LiF crystal soft X-ray detector allows obtaining contact and propagation-based phase-contrast images of nanostructures with 700 nm spatial resolutions in a wide field of view. It was demonstrated that the high precision of used techniques enable distinguishing inhomogeneity of measured intensities of ultrathin foils in the order of ±3%. All of this opens a new approach for PBPC imaging and metrology of full areas of free-standing or mesh-supported nano-thickness foils, or other nanostructures.

We have demonstrated a spatially coherent 13.9 nm laser with submicroJoule output energy using a double-target geometry with a new driver system. The new driver was a chirped-pulse amplification laser with zigzag slab Nd:glass power amplifiers providing two beams with an energy of 10 J and picosecond duration at a shot rate of 0.1 Hz. The obtained 13.9 nm laser pulse with 1010 coherent photons will enable us to carry out single-shot pump-probe observation of nonperiodic ultrafast phenomena.

Thin-film transistor (TFT) circuits with unprecedented high-frequency performances were fabricated. Based on sub-micron TFTs on phase-modulated-eximer-laser-annealing (PMELA) crystallized silicon films, low-voltage-differential-signaling (LVDS) receivers and low-noise-amplifiers (LNAs) were fabricated. The LVDS receivers can handle a data rate as high as 800 Mbps, and the maximum power gain of the LNAs is 19.8 dB at 1.33 GHz.