To investigate the possibility of their application to both high density dynamic and nonvolatile ferroelectric random access memories, heteroepitaxial BaxSr1-xTiO3 (BSTO) thin films with various Ba content from x=0 to 1. 0 were prepared on conductive SrRuO3 electrode films, and the crystallographic, dielectric and ferroelectric properties were investigated. The compositional phase boundary between paraelectric and ferroelectric phase at room temperature was located at about x = 0. 12 in the heteroepitaxial films, indicating a quite different composition to that of the bulk (x = 0. 70). At this composition of x = 0. 12, the dielectric constant attained the maximum value of 740 for the BSTO film with a thickness of 77 nm. The composition with a lager Ba content (x 0. 32) showed ferroelectricity at room temperature. The maximum value of remanent polarization of 2Pr = 0. 38 C/m2 was obtained at the composition of x = 0. 70 in this study.

Pb(ZrxTi1-x)O3 (PZT) thin films were prepared on various electrodes. When Ir system materials were used as electrodes, fatigue properties of PZT thin films were improved. Moreover, in the case of the PZT thin film on an Ir/IrO2 electrode, not only fatigue but imprint properties were clearly improved. We could find these improvements were caused by good barrier effect of IrO2 from secondary ion mass spectroscopy (SIMS) analysis. By applying these Ir system electrodes, we fabricated stacked capacitors on polycrystalline silicon (poly-Si) plugs. In spite of high temperature thermal processing, we found poly-Si plugs were ohmically connected with the bottom electrodes of the capacitors from hysteresis measurements and I-V characteristics, and could greatly expect them for practical use.

The crystallization process of Sr0. 7Bi2. 3Ta2O9 (SBT) ferroelectric thin films with different crystal orientations formed by chemical liquid deposition using an alkoxide precursor was investigated. One film showed strong c-axis orientation (a-type film), while another shows scarcely any c-axis orientation (b-type film). We report that the crystallization process was the same even when crystal orientation differed. Thin films first change from amorphous to fluorite fine grains; the fluorite grains then change to bismuth layer-structure grains. The different orientation of the SBT films is not caused by different crystallization process. Both SBT films with different crystal orientations consist of fine fluorite grains after 650 heat-treatment. Their leakage current density characteristics differ, however. The leakage current density of the a-type film was independent of the electric field, and showed a low value of 10-8 A/cm2. The leakage current density of the b-type film, however, was dependent on the electric field, and increased continuously with the increasing electric field. After 700 heat-treatment, both films consist of large grains with bismuth layer-structure and fine fluorite grains. The matrix of both films contains large grains with bismuth layer-structure that determines the leakage current density characteristics. Since the fluorite grain size after a 700 heat-treatment is the same as that after 650 heat-treatment, nucleation is predominant at the structural phase boundary from amorphous to fluorite. The bismuth layer-structure grains are large and single-crystal grains after both a 700 and 800 heat-treatment. Increased grain size predominates at the structural phase boundary from fluorite to bismuth layer-structure grains. Clearly, ferroelectric SBT films with bismuth layer-structure are crystallized in two steps, each having a different predominant crystal growth mechanism.

Sr0. 7Bi2. 3Ta2O9(SBT) films are drawing attention as fatigue-free materials. We prepared an SBT film containing discontinuous crystals in the Bi-layered compound using a misted deposition method. In comparison to films prepared by the spin-on method, leakage current was low and spontaneous polarization is high but saturation performance was low. The low saturation performance seems attributable to the inclusion of discontinuous crystals in the Bi-layered compound, while the low leakage current may be explained by the films smaller, denser particles, which form a film without voids, resulting in higher uniformity. The misted deposition method has advantages of finer grain size and higher uniformity.

A method has been developed for evaluating the wear durability and adhesion characteristics of ultrathin overcoat films. The relationship between the wear depth and applied load or between the wear depth and number of scanning-scratch cycles is used in AFM nanowear tests. Inherent wear durability, which is independent of adhesion or substrate hardness, can be evaluated from the relationship between wear depth and applied load at relatively low loads, and the adhesion characteristics can be evaluated from the relationship at relatively high loads. Wear durability can be evaluated with a small number of scanning-scratch cycles and adhesion with a large number of cycles.

We successfully observed curent-voltage (I-V) curves which showed the behavior of intrinsic Josephson junctions using Tl2Ba2CaCu2Ox (Tl-2212) thin films on MgO substrates by structuring mesas and measuring the electrical transport properties along the c-axis. For a 55 µm2 mesa, a hysteretic I-V curve was observed up to 80 K, which showed that series-connected SIS-type junctions are formed. Compared with the critical current density (Jc) of more than 106 A/cm2 parallel to the ab-plane, an anisotropic Jc of 1.4102 A/cm2 along the c-axis was observed at 4.9 K. By focusing on the I-V curve at lower bias current, the constant voltage jumps measured at the first seven branches were estimated to be 26 mV. The normal resistance (Rnk) of a unit SIS junction was estimated to be 580 Ω by substituting the measured voltage jump in the Ambegaokar and Baratoff relation. Using the calculation for McCumber parameter (βc), the capacitance (Ck) of the unit SIS junction was estimated to be 3.610-10 F/cm2 at 77 K. The IckRnk product was estimated to be 6.4 mV and the cut-off frequency (fc1/2πRnkCk) was calculated to be 3.1 THz at 77 K. The Jc and the hysteresis decreased with an increase in the mesa area, and finally, for a 300300µm2 mesa, a resistively shunted junction (RSI) like curve without hysteresis was observed up to 98 K. A Jc of 5.6101 A/cm2 along the c-axis was observed at 6.4 K. This may be explained by the higher content of conductive grain boundaries for a larger mesa area.

This paper describes a new reduction mechanism of the stress induced leakage current that is induced by step tunneling of electrons through the step tunneling sites. The concept of this mechanism is based on the deactivation of step tunneling sites for thin oxide. It is verified that the deactivation is electrically realized by the injected electrons int the sites. It is because the step tunneling probability of electrons though the deactivated sites is suppressed, since the electron capture cross section of the neutralized deactivation sites becomes extremely low. The deactivation scheme is as follows: (1) The deactivation of tunneling sites can be realized that the tunneling sites trapped holes change to neutralized tunneling sites due to electrons injection. (2) The injected electron can deactivate the activation tunneling sites only under energy level than the energy level of the injected electrons. It is shown that the above reduction phenomenon can be quantifiably with formulation. These results are very important for high reliable thin oxide films and for high performance ULSI.

To improve the emission properties of blue-emitting phosphor layer, SrS:Ce, we evaluated CeN instead of conventional CeCl3 as a starting material. We evaluated the composition and the crystallinity of the thin films using RBS and XRD methods. We also evaluated luminescent properties of EL devices using SrS:Ce phosphor layer. From the results of RBS and XRD measurements, we found that the concentration of the oxygen impurity in SrS:Ce thin films was decreased and the crystallinity of SrS:Ce thin films was improved when CeN is used. These results mean that the degradation of SrS:Ce thin films can be prevented by the use CeN. The evaluation of luminescent properties, shows that the luminance of SrS:Ce EL device is increased by the use of CeN.

In this paper we propose two methods, named the time smoothing and the scale smoothing respectively, to reduce the Gibbs overshoot in continuous wavelet transform. In is shown that for a large kind of wavelets the scale smoothing cannot remove the Gibbs overshoot completely as in the case of Fourier analysis, but it is possible to reduce the overshoot for any wavelets by choosing the smoothing window functions properly. The frequency behavior of scale smoothing is similar to that of the time smoothing. According to its frequency behavior we give the empirical conditions for selecting the smoothing window functions. Numerical examples are given for illustrations.

Detailed investigations of the microstructural properties of SrGa2S4:Ce3+ thin films grown by deposition from binary vapors (DBV) were carried out by X-ray diffraction analysis (XRD), energy dispersive X-ray diffraction measurements (EDX), electron probe microanalysis (EPMA), and X-ray photoelectron spectroscopy (XPS) depth profiling. The results indicate uniform distribution of the constituent elements in the nearly stoichiometric structure of the thin films. Photoluminescence (PL) data including absorption and luminescence spectra in the temperature range of 10 to 300 K and decay characteristics show that an increase in Ce concentration from 0.2 to 3 mol% is accompanied with a marked increase in both the intensity of activator absorption and decay time, while the emission and excitation bands remain fixed in position. A mechanism involving the concentration-dependent interactions between different centers in the lattice is proposed, which may explain the experimentally observed behavior.

Our compact switching converter using a thin-film microtransformer mono-lithically integrated with rectifier diodes represents the first step in developing a monolithic micro-switching converter that can be integrated with semiconductor devices and magnetic components. This converter is a single-ended forward converter with resonant reset and operates successfully at 15 MHz. The maximum output power is 0.5 W.

This paper describes what happens when the silicon layer is extremely thinned. The discussion shows that quantum mechanical short-channel effects impose limits on the down-scaling of MOSFET/SOI devices. However, thinning the silicon layer should bring new possibilities such as mobility enhancement, velocity overshoot enhancement, suppression of band-to-band tunneling, suppression of impact ionization and so on. Furthermore, the non-stationary energy transport in extremely miniaturized ultra-thin MOSFET/SOI devices is also addressed from the viewpoint of hot-carrier immunity. Related device physics are also discussed in order to consider the design methodology for contemporary MOSFET/SOI devices and new device applications for the future.

Integrating the power supply and signal processing circuit into one chip is an important step towards achieving a system-on-chip. This paper reviews and looks at the current technologies and their trends for power supply components such as DC-DC converters, intelligent power LSIs, and thin-film magnetic devices for the system-on-chip. A device structure has been proposed for the system-on-chip that is based on a quasi-SOI technique, in which the buried oxide layer is partially removed from the SOI substrate. In this structure, the CMOS devices for the digital signal-processing circuit and the bipolar transistors are formed in a conventional SOI region, and the CMOS analog devices and high-voltage devices are formed in a quasi-SOI region.

A new magnetostrictive thin-film cantilever actuator and a new thin-film walking mechanism were developed. The actuators were made of magnetostrictive amorphous Tb-Fe and Sm-Fe thin films, deposited on the opposite sides of a polyimide film substrate. These actuators need not power supply cables because they were remotely driven by external magnetic fields. The static deflection of a 3-mm-long cantilever actuator was as large as 100 µm at 300 Oe field. Moreover the application of ac resonant frequency field of the same intensity yielded deflection of above 500 µm. The walking mechanism ran as fast as in the order of cm/s. The forward and backward running were possible depending on the frequency of applied magnetic field. Such unique characteristics suggest that magnetostrictive thin-film actuators are useful in MEMS applications.

This paper deals with the scattering of a plane wave from a two-dimensional random thin film. For a Gaussian random disorder, a first order solution is derived explicitly by a probabilistic method. It is then found that ripples appear in angular distributions of the incoherent scattering. Furthermore, the incoherent scattering is enhanced in the directions of backscattering and specular reflection. Physical processes that yield such an enhanced scattering are discussed. Numerical examples of the coherent and incoherent scattering are illustrated in figures.

Unlike the time-consuming contour tracking method of snakes [5] which requires a considerable number of iterated computations before contours are successfully tracked down, we present a faster and accurate model-based landmarks" tracking method where a single iteration of the dynamic programming is sufficient to obtain a local minimum to an integral measure of the elastic and the image energy functionals. The key lies in choosing a relatively small number of salient land-marks", or features of objects, rather than their contours as a target of tracking within the image structure. The landmarks comprising singular points along the model contours are tracked down within the image structure all inside restricted search areas of 41 41 pixels whose respective locations in image structure are dictated by their locations in the model. A Manhattan distance and a template corner detection function of Singh and Shneier [7] are used as elastic energy and image energy respectively in the algorithm. A first approximation to the image contour is obtained in our method by applying the thin-plate spline transformation of Bookstein [2] using these landmarks as fixed points of the transformation which is capable of preserving a global shape information of the model including the relative configuration of landmarks and consequently surrounding contours of the model in the image structure. The actual image contours are further tracked down by applying an active edge tracker using now simplified line search segments so that individual differences persisting between the mapped model contour are substantially eliminated. We have applied our method tentatively to portraits of a class album to demonstrate the effectiveness of the method. Our experiments convincingly show that using only about 11 feature points our method provides not only a much improved computational complexity requiring only 0.94sec. in CPU time by SGI's indigo2 but also more accurate shape representations than those obtained by the snakes methods. The method is powerful in a problem domain where the model-based approach is applicable, possibly allowing real time processing because a most time consuming algorithm of corner template evaluation can be easily implemented by parallel processing firmware.

In the weakly coupled grain model which has been proposed to explain the residual surface resistance in high-Tc superconducting polycrystalline thin films, the superconducting polycrystalline thin films is described as a network of superconducting grains coupled via Josephson junctions. In order to evaluate this model we have fabricated the coplanar waveguide resonator using c-axis oriented YBa2Cu3Ox Thin Films and measured the residual surface resistance. The experimental results are in good agreement with theoretical prediction.

We report recent progress in the development of Liquid Crystal(LC) materials for the TN-TFT and ECB-TFT technologies, which require LC materials with positive and negative dielectric anisotropy, respectively. Many kinds of new LC materials have been synthesized and have been evaluated based on their fundamental physical properties. We have succeeded in identifying new LC materials, and developing new LC mixtures based on those, so that the current typical requirements of TFT-LCDs e.g. fast switching times, low power consumption, good viewing angles and wide operation temperature ranges together with high reliability can be fulfilled.

It is an important problem in fields of radar, sonar, and so on to estimate parameters of closely spaced multiple signals. The MUSIC algorithm with the forward-backward (FB) spatial smoothing is considered as the most effective technique at present for the problem with coherent signals in a variety of fields. We have applied this in Laser Microvision. Recently, Shimotahira has proposed the Kernel MUSIC algorithm, which is applicable to cases when signal vectors and noise vectors are orthogonal. It also utilizes Gaussian elimination of the covariance matrix instead of eigenvalue analysis to estimate noise vectors. Although the amount of computation by the Kernel MUSIC algorithm became lighter than that of the conventional MUSIC algorithm, the covariance matrix was formed to estimate noise vectors and also all noise vectors were used to analyze the MUSIC eigenspectrum. The heaviest amount of computation in the Kernel MUSIC algorithm exists in the transformation of the covariance matrix and the analysis of the MUSIC eigenspectrum. We propose a more straightforward algorithm to estimate noise vectors without forming a covariance matrix, easier algorithm to analyze the MUSIC eigenspectrum. The superior characteristics will be demonstrated by results of numerical simulation.

Amorphous silicon thin film transistors(a-Si TFTs) with a channel-etched structure were fabricated. The key technologies to realize these simple-process TFTs were 1) fabricating data lines and pixel electrodes of indium tin oxide(ITO); 2) carrying out tapered dry etching of plural layers of the a-Si and gate insulator silicon nitide; and 3) forming silicide layer to reduce the contact resistance between the phosphorousdoped a-Si and ITO. Excellent image quality, with a high contrast ratio of more than 100: 1, was obtained for video graphic array(VGA) mode TFT-LCDs using a dot inversion driving method. Furthermore, the transmission distribution was uniform with less than a 4.5% deviation on the whole display area although the ITO data line resistances were as large as 120 kΩ per line.