A three-dimensional analysis of Whispering-Gallery modes (W. G. modes) in a coaxial dielectric resonator is proposed and presented. The coaxial dielectric resonator is constructed from a lossy dielectric disk and ring which have diameters of several tens times as large as wavelength. Eigenvalue equations of the W. G. modes are derived rigorously from field expressions and boundary conditions. The resonant frequencies, unloaded Q values and field distributions are calculated numerically from the eigenvalue equations. These calculated results are in good agreement with experimental ones for an X band model. As a result, it is shown that a considerable quantity of modal energy can be confined in a loss-less gap between the disk and ring, and then the unloaded Q value is higher than that of a conventional dielectric disk and ring resonator.

We describe the characteristics of scattering and diffraction of plane E-waves by a lossy dielectric elliptic cylinder. The computational programs for calculating the analytic solutions for the diffraction of a lossy dielectric elliptic cylinder can be achieved. From the calculated results of the backscattering cross section (BSCS) (usually the radar cross section: RCS) and the forward-scattering cross section (FSCS) due to the cross-sectional shape and complex dielectric constant of the elliptic cylinder, the features of the BSCS and FSCS can be clarified as follows. (1) There is a cross-sectional shape of the cylinder which results in a minimum BSCS with a complex dielectric constant of the cylinder. (2) The BSCS and FSCS of the lossy dielectric scatterer approach zero as the scatterer approaches a strip. This result means that no material composing such a strip exists, and the features are very different from those in a perfectly conducting strip. (3) The influence of conductivity, σ, of the cylinder on a scattered wave is small for the relative dielectric constant of εr6. (4) The total scattering cross section of the lossy dielectric elliptic cylinder which causes the minimum BSCS is not small. Hence, it may be considered that the minimum BSCS is determined mainly by interference based on the cross-sectional shape and complex dielectric constant of cylinder, and is not caused by incident wave absorption due to the lossy dielectric.

A method using the microstrip line resonator is applied to measurements of the dielectric properties of a substrate and the surface resistance of a conducting strip line versus the frequency as well as the temperature. The variational expressions for the capacitance per unit length of several microstrip lines such as an inverted microstrip line and multi-layer microstrip lines are derived. The expression involves an integral along a semi-infinite interval, but the numerical integration is very easy. Effects of a buffer layer deposited on the substrate are investigated by using a multi-layer microstrip line model. The permittivity and the loss tangent of several dielectric materials are measured by the MSL and the IMSL or the multi-layer microstrip resonator. The measured surface resistance of copper and iron is also presented to show the validity of the present method. The surface resistance of a BSCCO thick film is also presented.

The progress of LSI technologies makes it possible to fabricate 256 MDRAM. However, it depends on the cost effectiveness of device fabrication that LSI memory can continue to be the technology driver or not. It is indispensable to make the device, process, and equipment as simple as possible for next generation LSI. For example, wavefront technologies in lithography, high energy ion implantation, and simple DRAM cell with SOI structure or high dielectric constant capacitor, are under development to satisfy both device performance improvement and process simplicity.

The dielectric resonator method is now widely accepted as a precise measurement method for determining the dielectric properties at microwave frequencies. This paper describes the measurement results of εr, tan δ and TCf determined by a round robin test of this method. The resultant measurement errors were Δεr/εr0.10%, Δtan δ0.5105 and ΔTCf0.5 ppm/K, where Δdenotes a standard deviation. The causes of measurement errors and the conditions to improve the measurement accuracy are discussed.

An image type resonator method is proposed as a method to evaluate precisely the temperature dependence of dielectric material. At first, the temperature coefficients of the resonant frequencies, TCf are measured separately using the shielded dielectric resonators of three types; that is a parallel plate type, and an image type, and a MIC type resonator. Secondly, an intrinsic temperature coefficient of the resonant frequency TCf0, which is defined as the temperature coefficient of a resonant frequency when all the stored energy is confined inside a dielectric, is estimated from these measured TCf. Actually, the TCf0 values of a sapphire and (ZrSn) TiO4 rod are estimated from the TCf values measured for the resonators of three types. As a result, for the parallel plate type, the precision of TCf0 is about 0.1 ppm/. For the image and MIC types, the errors of about 0.5 ppm/ in the TCf0 values arise from the errors in the linear expansion coefficients of the resonators, rather than from the experimental errors in TCf. Then, another image type resonator is designed to estimate TCf0 within error of 0.1 ppm/. In this design, dimensions of the shielding cavity is determined to reduce the influence of the errors in the linear expansion coefficients on precision of the TCf0 estimation. Finally, for a (ZrSn) TiO4 ceramic rod, a TCf0 value estimated from TCf measured for the image type resonator is obtained with accuracy of about0.1 ppm/.

For the study of the biological effects of ELF (Extremely Low Frequency) electric fields, the perception mechanism of ELF electric fields was analyzed. When a human body is exposed to an electric field, the hair on the body surface moves due to the electric force exerted on the hair. In theoretical analysis, it was shown that the force is approximately proportional to the dielectric constant of hair and the spatial gradient of the square of the electric field at the hair. The dielectric constant of hair was measured with different temperatures and humidities of the surrounding air. A technique was developed to estimate the electric force exerted on a hair during the field exposure. After experiments with model hair, the technique was applied to a body hair of a living human being. It was found that the force increased with field strength and relative humidity. The variations of the force agreed well with those expected from the theoretical analysis and the measurement of hair dielectric constants. These results explain the cause of the reported variation in the threshold of biological effects of an electric field. The results will help to establish a practical safety standard for the held exposure.

This paper describes a nondestructive measurement method for complex permittivity of dielectric material at pseudo microwave frequencies. The resonator used in this study has a cylindrical cavity filled with a sapphire material of a well known complex permittivity. The resonator is divided into two parts at the center. A dielectric substrate specimen is clamped with these halves. Relative permittivity εand loss tangent tan δ of the specimen are obtained at 3 GHz using the TE011 resonance mode. The accuracy of the present method is evaluated through the comparison of the measured values by the new method with those at around 10 GHz by the conventional empty cavity resonator method. The errors of measurements are smaller than 1% and 1105 for εand tan δ, respectively.

We describe a geometrical optics approach for the analysis of dielectric tapered waveguides. The method is based on the ray-optical treatment for wave-normal rays defined newly to waves of light in open structures. Geometrical optics fields are represented in terms of two kinds of wave-normal rays: leaky rays and guided rays. Since the behavior of these rays is different in the two regions separated at critical incidence, the geometrical optics fields have certain classes of discontinuity in a transition region between leaky and guided regions. Guided wave solutions are given as a superposition of guided rays that zigzag along the guides, all of which are totally reflected upon the interfaces. By including some leaky rays adjacent to the guided rays, we obtain more accurate guided wave solutions. Calculated results are in excellent agreement with wave optics solutions.

A modified beam propagation method based on the Galerkin's technique (FE-BPM) has been implemented and applied to the analysis of optical beam propagation in a tapered dielectric waveguide. It is based on a new calculation procedure using non-uniform sampling spacings along the transverse coordinate. Comparison with a conventional FE-BPM shows a definite improvement in saving computation time. The differences of a propagation field and a mean square power given by the proposed FE-BPM are discussed in comparison with the conventional FE-BPM.

This paper describes the formation of ultra-thin tantalum oxide capacitors, using rapid thermal nitridation (RTN) of the storage-node polycrystalline-silicon surface prior to low-pressure chemical vapor deposition of tantalum oxide, using penta-ethoxy-tantalum [(Ta(OC2H5)5) and oxygen gas mixture. The films are annealed at 600-900 in dry O2 atmosphere. Densification of the as-deposited film by annealing in dry O2 is indispensable to the formation of highly reliable ultra-thin tantalum oxide capacitors. The RTN treatment reduces the SiO2 equivalent thickness and leakage current of the tantalum oxide film, and improves the time dependent dielectric breakdown characteristics of the film.

The dielectric breakdown strength of thermally grown silicon dioxide films was studied for MOS capacitors fabricated on silicon wafers that were intentionally contaminated with magnesium and zinc. Most of magnesium was detected in the oxide film after oxidation. Zinc, some of which evaporated from the surface of wafers, was detected only in the oxide film. The mechanism of the dielectric degradation is dominated by formation of metal silicates, such as Mg2SiO4 (Forsterite) and Zn2SiO4 (Wilemite). The formation of metal silicates has no influence on the generation lifetime of minority carriers, however, it provides the flat-band voltage shift less than 0.3 eV, and forces to increase the density of deep surface states with the zinc contamination.

The dielectric breakdown characteristics of a thin gate oxide during high-current ion implantation with an electron shower have been investigated by controlling the energy distribution of the electrons. Degradation of the oxide has also been discussed with regard to the total charge injected into the oxide during ion implantation in comparison with that of the TDDB (time dependent dielectric breakdown). Experimental results show that the high-energy and high-density electrons which concentrated in the circumference of the ion beam due to the space charge effect cause the degradation of the thin oxide. It was confirmed that eliminating the high-energy electrons by applying magnetic and electric fields lowers the electron energy at the wafer surface, thereby effectively suppressing the negative charge-up.

This paper discusses the fully three-dimensional finite difference time domain (FDTD) method to analyze a monopole antenna mounted on a rectangular conducting box covered with a layer of dielectric. The effects of the conductivity and the permittivity of the dielectric layer are investigated. It is shown that all calculation results agree very well with the measured data.

Material research on capacitor dielectrics for DRAM applications is reviewed. The state of the art technologies to prepare Si3N4,Ta2O5, and SrTiO3 thin films for capacitors are described. The down-scaling limits for Si3N4 and Ta2O5 capacitors seem to be 3.5 and 1.5 nm SiO2 equivalent thickness, respectively. Combined with a rugged polysilicon electrode surface,Si3N4 and Ta2O5 based-capacitors are available for 256 Mbit and 1 Gbit DRAMs. At the present time, the minimum SiO2 equivalent thickness for high permittivity materials is around 1 nm with the leakage current density of 10-7 A/cm2. Among the great variety of ferroelectrics, two families of materials,i.e., Pb (Zr, Ti) O3 and (Ba, Sr) TiO3 have emerged as the most promising candidates for 1 Gbit DRAMs and beyond. If the chemical vapor deposition technology can be established for these materials, capacitor dielectrics should not be a limiting issue for Gbit DRAMs.

The finite-difference beam-propagation method is applied to the analysis of hollow slab waveguides (HSWs). The attenuation constants for the TE0 and TE1 modes are evaluated and compared with those obtained by the perturbation theory. The propagating field and differential power loss in the transition from a straight HSW to a bent HSW are revealed and discussed.

The characteristics of an open-boundary Cherenkov laser for an electromagnetic wave with a continuous frequency spectrum are numerically analyzed. A given power spectral density for the input wave is found to get concentrated around the frequency where the spatial growth rate is maximum, as it grows along the electron beam. In addition, the frequency for the maximum growth rate is found to shift gradually to higher values. Furthermore, by gradually increasing the permittivity of the dielectric waveguide along it, we can always get the maximum power spectral density at the frequency where the spatial growth rate initially becomes maximum at the input.

The effective dielectric constant εeff of discrete random medium composed of many dielectric spheres has been analyzed by EFA (Effective Field Approximation), QCA (Quasicrystalline Approximation) and QCA-CP (Quasicrystalline Approximation and Coherent Potential) in the case where the optical path length is very large in the medium. These methods lead to a reasonable K for non-large dielectric constants of spheres, while their methods yield an unphysical dependence of εeff on large dielectric constants of spheres: that is, the εeff does not become large for increasing the dielectric constant. In this paper, we remove the unphysical dependence and present new results for εeff of our method, comparing with the results for εeff of EFA, QCA and QCA-CP.

In order to explain the temperature and frequency characteristics of high-Tc superconductors, a new model is proposed, which will be called the improved three-fluid model, where the momentum relaxation time τ is assumed to depend on temperature in the superconducting and normal states, respectively, although τ has been assumed to be independent of temperature for the conventional three-fluid model. According to this model, the complex conductivity σ1jσ2 and the surface impedance ZsRsjXs, where Rs is the surface resistance and Xs is the surface reactance, are expressed as a function of temperature. The temperature dependences of Zs and for a YBCO bulk estimated using this model agree very well with ones measured by the dielectric-loaded cavity method in room to cryogenic temperature. In particular, a peak of σ1 observed just below the critical temperature Tc in experiments, appeared in the calculated results based on this model. This phenomenon has been already known in the BCS theory. Thus, it is verified that this model is useful to explain the microwave characteristics of high-Tc superconductors in room to cryogenic temperature. On the other hand, the residual normal electron density nres4.2541023 m-3 and the total electron density nt7.3081024 m-3 are obtained by calculation. The ratio nres/nt0.058 can be used as figure of merit to evaluate material quality of high-Tc superconductors; thus it means that there is 5.8% nonpairing electron in this YBCO bulk.

Scaling-down of MOSFETs (metal-oxide-semiconductor field effect transistors can be divided to semi-classical and quantum mechanical one. In the regime of semi-classical scaling-down the behavior of electrons and holes can be well described with the effective mass approximation and in the regime of quantum mechanical scaling-down the characteristics of electrons and holes as wave becomes markedly. The minimum size limit of MOSFETs scaled down in semi-classical regime is mainly determined by the subthreshold characteristics and the short channel effect on the threshold voltage and 0.1 µm will be the minimum channel length from practical viewpoints. Scaling down of MOSFETs enhances their operational speed, but the substrates with high resistivity which are often used in SOI (silicon on insulator) substrates result longer dielectric relaxation time. While the dielectric relaxation time becomes longer than the reciprocal of signal frequency, the semiconductors work as lossy dielectrics and may lead to new types of dynamic circuits. Modification of material properties utilizing the wave nature of electrons is an illustration of quantum mechanical way to improve characteristics of MOSFETs. Suppression of optical phonon scattering of two dimensional electrons by introducing two dimensional array of quantum dots into substrates is expected to improve high field characteristics of material. Brillouin zone folding is another way to control the band structure of materials, especially to make the indirect transition band structure to the direct transition band structure. Heat transfer from a chip severely limits the number of devices which can be integrated on the chip. Reduction of signal charge to electronic elementary charge, that is quantum limit, is expected to be useful for realization of nano-power electronics.