Thermal desorption spectroscopy (TDS) is applied to analyze the oxidation reactions of hydrogen-terminated Si(100) surfaces in both the heating and cooling processes after hydrogen desorption. The oxidation reaction of oxygen and water with a silicon surface after hydrogen desorption shows hysteresis in the heating and cooling processes. In the cooling process, oxidation finishes when the silicon surface is adequately oxidized to about a 10 thickness. Oxidation continues to occur at lower temperatures when the total volume of oxygen and water is too small to saturate the bare silicon surface. The reaction of water with silicon releases hydrogen at more than 500. Hydrogen does not adsorb on the silicon oxide surface. A trace amount of oxygen, less than 110-6 Torr, roughens the surface.

This paper proposes three configurations of slow-wave transmission lines for MMICs, i.e., double crosstie slow-wave transmission line (DCT-SLW), meander-like DCT-SLW and lumped DCT-SLW. The DCT-SLW is based on periodic structures and triplate structures. The meander-like DCT-SLW realizes a drastic size reduction in the DCT-SLW using a meander configuration of inductive and capacitive transmission lines. The multilayer spiral inductors are introduced to obtain high impedance characteristics of the meander section. The lumped DCT-SLW achieves a large slow-wave factor of 30. These proposed structures are analytically and experimentally investigated, and excellent performance is obtained. It is also shown that the proposed DCT-SLWs are superior to thin film microstrip (TFMS) lines with the same insertion phase, as regards size.

An application of wavelength conversion laser diodes (WCLDs) to a photonic cross-connect system using wavelength-division (WD) technology is presented. We propose a novel WD photonic cross-connect node architecture with multiwavelength selective filters. By using the filters, we can construct a nonblocking cross-connect switch by 2-stage connection. Next we describe the requirements to the optical devices in our switch, especially to the wavelength conversion devices in configuring a multistage connection of our switch. Finally, we have conducted the wavelength switching experiments using our wavelength conversion laser diode at a bit rate of 125Mb/s and shown its applicability to a WD photonic cross-connect system with over 3,000 channels.

According to the development of optical communication technologies, it is getting easier to handle new devices, such as optical fibers, semiconductor light sources, guided wave devices, and optical integrated circuits. These devices have recently given considerable impact on the optical sensing field. The optical sensing shares the optical devices and the concepts of signal processing or system configuration with the optical communication. In this paper, the advanced lightwave sensing technology is discussed, considering the relation to the advanced optical communication technology. Distributed fiber sensors and the application of coherence characteristics of semiconductor light sources are the topics to be mainly discussed. In the distributed fiber sensors, the fiber plays both a role of low-loss transmission line and a role of lengthwise deployed sensing element. According to the change of characteristics of light propagating in the fiber, distribution of various physical parameters can be measured, such as the fiber loss, temperature, and strain. Optical Time Domain Reflectometry is employed to determine the location. Another tendency in the lightwave sensing field is the use of coherence characteristics of various semiconductor light sources. Low coherent source provide a highly sensitive inertial rotation sensor, that is, interferometric fiber optic gyroscope. Another type of optical gyroscope, optical passive ring-resonator gyro, has been studied as an application of a high coherence source. Frequency tunability of the semiconductor laser, especially that of tunable DFB or DBR lasers, can provide new ways in signal processing in the sensors. Optical coherence function can be synthesized also by utilizing the tunability. In conjunction with the progress in optical communication, lightwave sensing fields are steadily increasing.

A layout system for mixed analog/digital standard cell LSI's is described. The system includes interactive floorplan and placement features and automatic global and channel router. In mixed analog/digital circuits, crosstalk noise causes chip performance degradation. Thus, the proposed global routing algorithm routes analog nets in areas that are free of digital nets as much as possible. The number of line crossovers, especially for analog nets, is minimized by both global and detailed routers, because these crossovers are the dominant factors in the crosstalk noise. Double width lines can be used to avoid unexpected voltage drops caused by parasitic resistances. A postprocess automatically puts up shield lines for very noise sensitive wirings to improve the S/N ratio. Experimental results show that the proposed algorithms are effective in reducing the number of crossovers and redundant vias.

Splice Loss of LP modes in multimode graded-index optical fibers is investigated. It becomes clear that splice loss of particular mode and the excitation rate of the other modes by mode conversion is predicted from the factor, e.g. fiber axis misalignment, fiber and face gap, end fiber end face inclination.

In speech output expected as an ideal man-machine interface, there exists an important issue on emotion production in order to not only improve its naturalness but also achieve more sophisticated speech interaction between man and machine. Speech has two aspects, which are prosodic information and phonetic feature. For the purpose of application to natural and high quality speech synthesis, the role of prosody in speech perception has been studied. In this paper, prosodic components, which contribute to the expression of emotions and their intensity, are clarified by analyzing emotional speech and by conducting listening tests of synthetic speech. The analysis is performed by substituting the components of neutral speech (i.e., one with no particular emotion) with those of emotional speech preserving the temporal correspondence by means of DTW. It has been confirmed that prosodic components, which are composed of pitch structure, temporal structure and amplitude structure, contribute to the expression of emotions more than the spectral structure of speech. The results of listening tests using prosodic substituted speech show that temporal structure is the most important for the expression of anger, while all of three components are much more important for the intensity of anger. Pitch structure also plays a significant role in the expression of joy and sadness and their intensity. These results make it possible to convert neutral utterances into utterances expressing various emotions. The results can also be applied to controlling the emotional characteristics of speech in synthesis by rule.

We have developed a new model to analyze the thermal failure mechanism due to electrical-over-stress (EOS) for two-dimensional planar pn-junction structures where the failure power is proportional to about 1/5 power of the failure time. We adopted a pseudo two-dimensional numerical simulation method where a pn-junction diode is divided into small elements and represented by a circuit network composed of many minute resistors and diodes. The failure mechanism studied by Wunsch and Bell, that is one of many studies for one-dimensional pn-diodes, is not valid for the case of two-dimensional pn-junction, such as a planar type junction. On the contrary, the failure mechanism was found to be much correlative with the junction structure, especially the impurity concentration in the substrate in the two-dimensional case. When the impurity concentration in the substrate is high enough (e.g. Nsub1017[cm-3]), the breakdown occurs at the whole junction. The heat transfer is one-dimensional and the failure power is proportional to about 1/2 power of the failure time, which is well known results reported by many researchers: e.g. Wunsch &Bell. On the other hand, when the impurity concentration in the substrate is low enough (e.g. Nsub1016[cm-3]), the breakdown occurs locally at the junction edge. The heat transfer is two-dimensional and the failure power is in proportion to about 1/5 power of the failure time.