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Electrochemical quartz crystal microbalance (EQCM) measurements were carried out during electrochemical deposition/dissolution of Li on the Ti and Pt substrate electrodes of AT-cut quartz crystals in a 1 M LiPF 6 in propylene carbonate (PC) and dimethoxyethane (DME) (1:1 in volume) and a 1 M LiPF 6 in ethylene carbonate (EC) and DME (1:1 in volume). The mass change during Li deposition on the Pt substrate was about half that on the Ti substrate because the alloy formation of Li–Pt suppressed passivation reactions of deposited Li. Furthermore, it was also suggested that the amount of organic compounds in passivation films formed in the PC-based electrolyte was larger than that in the EC-based electrolyte due to PC reacting more easily with Li than EC. The EQCM measurement of the passivation film formations during alloying Li with Pb electrodeposited on the Ti substrate was also conducted successfully. The Li–Pb alloy formation occurred under 0.5 V, in which the potential profile was divided into two regions associated with the phase diagram of Li–Pb alloy. The mass change due to passivation film formations increased in accordance with the changes of Li–Pb alloy compositions into Li rich phases, which were thought either to enhance the reactiveness of Li or decrease the diffusiveness of Li in Li–Pb alloy.

5週間の短期間で長期のコンクリートの乾燥収縮ひずみを判定する乾燥収縮迅速評価システムを開発し，多くの実工事に関連するレディーミクストコンクリートに適用した。本システムの開発にあたり，省力化の実現が可能な乾燥収縮の試験方法として省力化乾燥収縮試験法を提案するとともに，長期の乾燥収縮ひずみを短期データから予測する予測手法として外挿法を提案した。本システムを，実工事に関連する280調合のレディーミクストコンクリートに適用するとともに，長期の乾燥収縮ひずみを短期間の測定デ―タから高い精度で判定できることを確認した。

We calculated intravalley and intervalley phonon scattering rates of accelerated electrons under intense midinfrared laser fields. We extended the Keldysh theory, which assumes oscillatory motion of Bloch electrons driven by intense laser fields, to phonon scattering of electrons in semiconductors. We find that phonon emission is possible even if the initial electron energy is less than the phonon energy due to multi-photon absorption processes. We also find that the scattering rates increase with electric field strength and wavelength. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We have measured optical transmittance through germanium in the mid-infrared region at room temperature using the Osaka free-electron laser (FEL). In spite of the fact that germanium is transparent in the mid-infrared region, we observed strong suppression of optical transmission under high-intensity FEL excitation. We found that the observed suppression is due to optical absorption in germanium. To analyze the experimental results, we have calculated optical transmittance of germanium within Keldysh theory

In order to investigate formation process of electronic quantum states in a confined system, we simulate motion of a wavepacket state and show how an eigenstate is formed due to coherence of electronic wave from the viewpoint that an eigenstate arises as a result of self-interference of a moving electron. Numerical results for a Henon–Heiles potential in which chaotic motion can occur in the classical mechanics indicate that electronic eigenstates can arise even when motion of an electron is non-periodic. The results show that, in the quantum mechanics, periodicity is unnecessary for the formation of eigenstates.

We fabricated side-gated quantum-dot structures on a GaAs/AlGaAs single heterostructure and measured their magnetoresistance at low temperature. We observed that oscillations appear almost periodic in B for a lower magnetic field region. We find that the oscillation period is fairly independent of the structure width. The experimental magnetoconductance are compared with numerical results.

Various temperature measurements of cyclotron resonance (CR) under pulsed ultra-high magnetic field up to 160 T were carried out in InGaAs/GaAs superlattice (SL) and InGaAs/AlAs SL samples grown by molecular beam epitaxy on GaAs substrates. Clear free-electron CR and impurity CR signals were observed in transmission of CO2 laser with wavelength of 10.6 μm. A binding energy of impurities in these SLs was roughly estimated based on the experiment as result, and we found it was smaller than the previous experimental result of GaAs/AlAs SLs and theoretical calculation with a simple model.

The CLIO project including a 100 m baseline cryogenic gravitational wave laser interferometer and a 100 m baseline geophysical strain meter was conducted in the Kamioka mine in Japan to investigate the technical feasibility of the large-scale cryogenic gravitational wave telescope (LCGT), which is planned to be constructed in the same Kamioka mine with 30 times longer baseline than CLIO, and to demonstrate the collaborative operation between these instruments about long-term continuous operation and gravitational wave signal veto analysis. About the cryogenic gravitational wave interferometer, the whole vacuum system and four cryostats, which house and cool sapphire mirrors, were constructed, and the required vacuum level of 10 −6 mbar and the temperature of 8 K at the inner radiation shield in the cryostat were achieved. About the geophysical strain meter, the obtained geophysical strain in the Kamioka mine was successfully simulated with a finite element model with a good agreement with less than 5% error. The strain meter also verified a permanent ground step change of micrometre order due to some earthquakes. We present the recent progress about the CLIO project.

A 100 m laser strainmeter system was installed in a deep tunnel about 1000 m below the ground surface in Kamioka, Gifu, Japan in 2003. The system consists of three types of independent interferometers: (1) an EW linear strainmeter of the Michelson type with unequal arms, (2) an NS–EW differential strainmeter of the Michelson type with equal arms and (3) an NS absolute strainmeter of the Fabry–Perot type. These are configured in L-shaped vacuum pipes, each of which has a length of 100 m. (1) and (2) are highly sensitive (order of 10−13 strain) and have wide dynamical range (10−13 to 10−6). Based on data obtained from these strainmeters (1) and (2) during the period of about 4 months in 2003, we analyzed tidal strains by employing the tidal analysis program BAYTAP-G. Observed tidal strain amplitudes of eight major constituents were compared with theoretically expected ones that were obtained from the GOTIC2 program. As a result, it was revealed that the “observed” amplitudes are about 10–20% smaller than the “expected” amplitudes. In order to explain these discrepancies, we examined the topographic effect using three-dimensional finite element model (3D FEM), and succeeded in reducing the discrepancies within several percent. This result shows that our laser strainmeter system in Kamioka has sufficient reliability to detect small strain changes of the order of 10−10 in the tidal frequency band.

We have installed a laser strainmeter system in a deep tunnel about 1,000 m below the ground surface at Kamioka, Gifu, Japan. The system consists of three types of independent interferometers: (1) an EW linear strainmeter of the Michelson type with unequal arms, (2) an NS-EW differential strainmeter of the Michelson type with equal arms and (3) a NS absolute strainmeter of the Fabry–Perot type. These are configured in L-shaped vacuum pipes, each of which has a length of 100 m. (1) and (2) are highly sensitive (order of 10−13 strain) and have wide dynamical range (10−13–10−6). Observations with strainmeters (1) and (2) started on June 11, 2003. (3) is a new device for absolute-length measurements of the order of 10−9 of a long-baseline (100 m) Fabry–Perot cavity by the use of phase-modulated light. This third strainmeter will be ready for operation before the end of 2004. The laser source of strainmeters (1) and (2) is a frequency-doubled YAG laser with a wavelength of 532 nm. The laser frequency is locked onto an iodine absorption line and a stability of 2 × 10−13 is attained. The light paths of the laser strainmeter system are enclosed in SUS304 stainless steel pipes. The inside pressure is kept to be 10−4 Pa. Consequently, quantitative measurement of crustal strains of the order of 10−13 can be attained by employing the laser strainmeter system of (1) and (2) at Kamioka. This resolving power corresponds to that of a superconducting gravimeter. Using the laser strainmeter system, we expect to determine parameters related to fluid core resonance, core modes and core undertone as well as other geodynamic signals such as slow strain changes caused by silent earthquakes or slow earthquakes.

The CLIO project involves the Cryogenic Laser Interferometer Observatory (CLIO) detector complex for gravitational wave detection and the Kamioka Laser Interferometric Strainmeter for the acquisition of geophysical data. CLIO has been constructed to demonstrate the feasibility of a future project, the Large-scale Cryogenic Gravitational wave Telescope (LCGT). It will utilize the low seismic and stable environment of the Kamioka mine as well as sapphire mirrors and suspension fibres at low temperature to reduce thermal noise. We designed CLIO to have a noise level limited by the thermal noise of sapphire mirrors and sapphire suspension fibres, which vary from 3 × 10−19 m Hz−1/2 at 300 K to 2 × 10−20 m Hz−1/2 at 20 K around 100 Hz. The strainmeter has already succeeded in monitoring the Earth's tidal motion with a strain sensitivity of 2 × 10−12. The seismic noise veto between these same-scale interferometers is expected to provide an effective means of data selection for the gravitational wave signal analysis, and the ground motion data obtained by the strainmeter will help to maintain the stable operation of CLIO.

Construction of CLIO (cryogenic laser interferometer observatory) with 100 m baseline length has begun in the Kamioka mine. The tunnel for CLIO has been dug and infrastructure work is now in progress. CLIO is the final step to LCGT (large scale cryogenic gravitational wave telescope) and the first practical construction of a cryogenic interferometer in the world. The objective of CLIO is to demonstrate two of three features of LCGT, which are to utilize the quietness and stable environment of the underground site and to adopt cryogenic sapphire mirrors for thermal noise reduction. Also, it is a joint project by gravitational wave and geophysics researchers. CLIO has a locked Fabry–Perot configuration equipped with ring mode cleaners and cryocoolers to cool the sapphire mirrors to 20 K. The noise level of CLIO is designed to trace the thermoelastic noise of sapphire mirrors which varies from 10−18 m Hz−1/2 at 300 K to 10−19 m Hz−1/2 at 20 K around 100 Hz. A 7 m single-arm cryogenic test facility has been built at ICRR (Institute for Cosmic Ray Research), while the 20 m room temperature interferometer is in operation at Kamioka. Technical knowledge developed by these prototypes will be leveraged to realize CLIO.

Cyclotron resonance (CR) measurements have been carried out to evaluate the effective mass of electron in (InGaAs)n/(GaAs)nsuperlattices (SLs) and (InGaAs)n/(AlAs)nSLs. To clarify the dependence of cyclotron mass on the monolayer numbern , we measured CR signals using pulsed high-magnetic fields up to 150 T and a far-infrared laser. We found clear cyclotron resonances in the transmission of 10.6 μ m at 75 T at room temperature in (InGaAs)n/(GaAs)nSLs and little dependence on the monolayer number n in the SLs. However, for (InGaAs)n/(AlAs)nSLs, a large dependence of cyclotron mass on the monolayer number n was observed. We consider that these dependencies are related to the difference between the barrier height in the SLs and the influence of nonparabolicity on the conduction subbands in the SLs.

Since 1992 the Lithium Battery Energy Storage Technology Research Association (LIBES) has been conducting a 10-year research and development project, ‘Development of the Dispersed-type Battery Energy Storage Technology’, on two types of batteries, an electric vehicle (EV) application type and a stationary type for a home-use energy storage system for load leveling. After the first interim evaluation in 1995, the work load of the battery developers in LIBES was divided into the following two groups: one is the group for the development of large-scale cells and battery modules with four approaches; and the other is the group for the development of next-generation battery technologies including lithium polymer battery technology. The aim of the research and development of lithium polymer battery technology in LIBES is to develop the solid-state lithium polymer battery using carbon material as the anode. Our laboratory has developed and improved a random copolymer of ethylene oxide and propylene oxide (SPE(B)) as one of the candidate polymer electrolytes.

We present a review on recent study of the type I to type II transition in short-period superlattices (SLs) of GaAs/AlAs by means of cyclotron resonance (CR) in pulsed high magnetic fields. The behavior of CR varies depending on the thickness of the GaAs and AlAs layers. In CR of (GaAs) n /(AlAs) n , the resonance peak at the X minima was observed in the type II regime for n smaller than 14, whereas the resonance at the Γ point was observed for n >15. We estimated electron masses on X and Γ point in the SLs by using the empirical sp 3 tight-binding method including second-nearest-neighbor interaction. These calculations have shown good agreement with the experimental results. Moreover, it was found that the angular dependence of the CR peak position does not obey the simple cosine dependence due to the subband mixing in high magnetic fields. From the angular dependence in the SLs, the longitudinal and transverses electron masses of AlAs at the X point were deduced to be m t =0.21 m 0 and m l =1.04 m 0 , respectively.

The Lithium Battery Energy Storage Technology Research Association (LIBES) has been conducting R&D on large-scale lithium secondary batteries for use in electric vehicles and home-use load leveling systems as part of the New Sunshine Program by the Agency of Industrial Science and Technology (AIST) of the Ministry of International Trade and Industry (MITI) under a contract with the New Energy and Industrial Technology Development Organization (NEDO) since FY 1992. The R&D by LIBES, which is in Phase 2, has developed several hundred Wh class prototype cells of 4 types and 2 or 3 kWh class modules of each type connecting those cells in series. At the same time, LIBES member companies are conducting studies on supporting technologies for the above R&D, on the evaluation test, and on next-generation lithium secondary battery technology development. Here we describe the current results and status of LIBES's R&D as well as those technological aspects.

We have carried out measurements of cyclotron resonance (CR) in type-I (GaAs)n/(AlAs)n superlattices (SLs) applying pulsed high magnetic fields up to 150 T. Two types of peaks have been observed in CR signals; one originates from a transition between Landau levels of free electrons, and the other from transition between impurity levels. The free-electron CR signals are dominant at room temperature, and the impurity CR signals become large as temperature decreases. From the peak position of CR spectra, at room temperature, the effective mass of the electron in (GaAs)n/(AlAs)n SL is deduced. To analyze the impurity transition in high magnetic fields, we have calculated the impurity levels in the SLs using the variational method assuming a single quantum well for simplicity. In spite of a very simple model, the calculated results are in good agreement with the CR results of type-I (GaAs)n/(AlAs)n SLs.

A 60-mW MPEG4 video codec has been developed for mobile multimedia applications. This codec supports both the H.263 ITU-T recommendation and the simple profile of MPEG4 committee draft version 1 released in November 1997. It is composed of a 16-bit reduced instruction set computer processor and several dedicated hardware engines so as to satisfy both power efficiency and programmability. It performs 10 frames/s of encoding and decoding with quarter-common intermediate format at 30 MHz. Several innovative low-power techniques were employed in both architectural and circuit levels, and the final power dissipation is 60 mW at 30 MHz, which is only 30% of the power dissipation for a conventional CMOS design. The chip was fabricated in a 0.3-/spl mu/m CMOS with double-well and triple-metal technology. It contains 3 million transistors, including a 52-kB on-chip SRAM. Internal supply voltages of 2.5 and 1.75 V are generated by on-chip dc-dc converters from 3.3-V external supply voltage.

We have carried out cyclotron resonance (CR) measurements of (InGaAs) 8 /(AlAs) 8 superlattice (SL) to investigate electronic properties of the SL under pulsed ultra-high magnetic fields. The magnetic fields up to 160 T were generated by using the single-turn-coil technique. Clear CR signals were obtained in the transmission of far-infrared laser through the SL at room temperature and lower temperature. We observed a shift of CR peak to lower magnetic field caused by transition from free-electron CR to impurity CR below ∼90 K. Compared with the previous works or GaAs/AlAs SL, the peak shift was small and the transition temperature was low. This result suggests that a binding energy of the impurity in the InGaAs/AlAs SL is smaller than the GaAs/AlAs SL.

Functional mapping was carried out to address the amino acid residues responsible for the activity of the antibacterial peptide apidaecin from the honeybee by an in vivo assay system developed previously. The C-terminal region and many of the proline and arginine residues which are present at high frequency in apidaecin were found to play an important role in its antibacterial activity.

We present a review on the recent study of the type I to type II transition in short-period superlattices of GaAs/AlAs by means of cyclotron resonance and interband magneto-optical spectroscopy in pulsed high magnetic fields up to 500 T. In the magneto-photoluminescence spectra of excitons in , the magnetic-field-induced type I to type II transition was observed with and without the simultaneous application of high pressure. The behaviour of the transition varies depending on the thickness of the AlAs layers. In cyclotron resonance of , the resonance peak at the X minima was observed in the type II regime for n smaller than 14, whereas the resonance at the point was observed for n>15. It was found that the angular dependence of the peak position does not obey the simple cosine dependence due to the subband mixing in high magnetic fields. From the angular dependence, the effective masses at the X point were determined. In high-field cyclotron resonance measurements at 129 meV up to 400 T for n = 16 (type I), the resonance of the X minima expected at around 260 T was indiscernible, despite the fact that the transition should have occurred at lower fields.

Cyclotron resonance (CR) measurements have been carried out to evaluate the effective masses of electrons at the AlAsX point of the Brillouin zone in short period (GaAs)n/(AlAs)n superlattices (SLs) with n = 8–14. The longitudinal effective mass was deduced to be m1 = 1.04m0 by analyzing a deviation of CR position from the cos φ-dependence for tilted magnetic fields in (GaAs)14/(AlAs)14 SL.

We report on recent investigations of electron transport characteristics in the transition regime from a two-dimensional (2DEG) to a one-dimensional electron gas (1DEG). Electron transport is studied in novel deeply etched side gated quantum wire structures. We observed enhanced electron mobility transport with increasing one dimensionality in a GaAs/AlGaAs quantum well wire structure. However, no mobility enhancement is measured in a GaAs/AlGaAs single heterostructure wire. This controversial behavior is attributed to electron density related screening effects as well as gate voltage induced changes of the confinement potential.

Cyclotron resonance measurements have been carried out to evaluate the effective mass of electrons in short-period (GaAs)n/(AlAs)n superlattices (SLs). In order to clarify the Γ-X crossover occurring at n ≈ 12 due to the zone folding effect, we have measured effective masses in SLs with n ranging from 8 to 16 using cyclotron resonance in high magnetic fields (up to 150 T). We found a clear cyclotron resonance in the transmission of 10.61 μm radiation at 99 T in type I SLs (corresponding to an effective mass of 0.098m0 and broad cyclotron resonances at around 90 T in type II SLs in the transmission of 23 μm radiation, which give an effective mass of 0.21 ± 0.01m 0. These resonances were found to be nearly independent of the number of monolayers n.

We have investigated electron transport in side-gated single quantum wires. The wires were produced by deep etching in GaAs/AlGaAs single and quantum well heterostructures. With increasingly negative gate voltage we observed a clear transition from a two-dimensional electron gas (2DEG) to a quasi-one-dimensional electron gas (1DEG). For the first time, enhanced mobility transport is detected in the GaAs/AlGaAs quantum well wire structure whereas a mobility loss occurs in the GaAs/AlGaAs single-heterostructure wire. The controversial behaviour is attributed to electron-density-related screening effects as well as gate-voltage-induced changes of the confinement potential in the growth direction favouring the quantum well wire structure in terms of high-electron-mobility 1DEG transport.

We determined the complete amino acid sequence of a novel subtilisin inhibitor, SIL15, which had been isolated from the culture supernatant of Streptomyces bikiniensis and shown to be a member of the Streptomyces subtilisin inhibitor (SSI)-like (SIL) protein family, and then identified its reactive site. SIL15 is composed of 113 amino acids and exists as a dimer. Compared with other SSI-family inhibitors, SIL15 was found to be unique in that it possesses a Gln residue at the P1 site of the reactive site and has two-residue insertions in two regions, one in the alpha 1-helix and the other in the flexible loop region near the reactive site. Inhibition of subtilisin BPN' by SIL15 (inhibitor constant, 2.7 x 10(-11) M) was due to the presence of a Gln residue at the P1 site, which was well consistent with the results obtained for P1-site mutants of SSI and turkey ovomucoid domain 3.

A unique antibacterial peptide derivative found in immune honeybee lymph, apidaecin 1b (AP1), was randomly mutagenized and characterized by a newly established system to analyze in vivo its structure-function relationship. Initially, a high-level expression host-vector system for AP1 in Escherichia coli was constructed by creating a fusion protein with the highly stable Streptomyces subtilisin inhibitor (SSI) molecule. Expression of the SSI-AP1 fusion protein was found to depend on the concentration of the transcriptional inducer isopropyl-beta-D-thio-galactopyranoside (IPTG) and to parallel the degree of growth inhibition of the transformant cells. Subsequently, apidaecin derivatives produced by localized random mutagenesis were screened with this IPTG concentration-controlled in vivo system by monitoring the growth inhibition patterns of the transformant cells. One mutant apidaecin (P9L) that had reduced activity was purified and isolated from the periplasmic fraction of an E. coli transformant. Its antibacterial activity was reduced to one-third of that of wild-type apidaecin. When considered together with the other mutations, it was concluded that several Pro residues, including that at the ninth position, are responsible for expression of the antibacterial action of apidaecin.

The magnetophonon resonance (MPR) effect has been used since the mid-1960s to investigate effective mass, optical-phonon energy and electron-phonon interaction in bulk III–V compounds [1–5]. Several authors have also studied MPR effect in two-dimensional (2D) systems, such as GaAs/AlGaAs, GaInAs/InP, and GaInAs/AlInAs heterostructures [6]. The MPR effect manifests itself as an oscillatory behavior of transverse-conductivity σ xx as a function of applied magnetic field B. At high magnetic fields, electrons move perpendicularly to both electric and magnetic fields, and the transverse-current is carried by electron-hopping motion induced by some scattering mechanisms. The MPR effect arises from the resonant absorption or emission of longitudinal-optical (LO) phonons by electrons when the Landau level is sharp and well defined, and scattering by LO phonons makes a significant contribution to limiting electron mobility. As the magnetic field increases, a small part of σ xx resonantly increases each time the integral multiple of the Landau level spacing becomes equal to the LO phonon energy, because the scattering of the electrons takes place with resonant absorption or emission of LO phonons. In bulk materials and 2D systems, the oscillatory part of σ xx is therefore proportional to the Frohlich coupling constant α, and the resonance condition where σ xx becomes maximal is written as $$ \hbar {\omega _{LO}} = P\hbar {\omega _c}(P = 1,2,3, \cdots ),$$ (2.3.1) where ħω LO is the LO phonon energy, P the resonance index, and ħω c = ħeB/m the cyclotron energy. From the measurement of the MPR effect, effective mass in or LO phonon energy ħω LO can be deduced, provided that one of the two is known. In order to observe the MPR effect, the temperature must be high enough to have a sufficient phonon population, but not too high, since the thermal broadening of the Landau levels reduces the oscillation amplitude. Optimal temperatures are known to be usually in the range 100–250 K for III-V materials.

We have investigated the magnetotransport properties of quantum wires which were fabricated on high-mobility GaAs/GaAlAs modulation-doped heterostructures by laser holography. For high temperatures (~ 150 K), magnetoresistance structures are revealed, which are due to the occurrence of magnetophonon resonances in the wire. This effect is used to determine the polaron mass which is found to be about 10% larger than to the polaron mass in bulk GaAs. In addition, hydrostatic pressure is used to modify the electron density in these quantum wires. We observe an increase of the 1D subband energy spacing with a decreasing electron density and an enhancement of the magnetophonon resonance amplitudes.

We report on the experimental studies of photoluminescence from hot electrons in quantum wires which were fabricated on AlGaAs/GaAs hetero-structures by using electron beam lithography and wet chemical etching. Spatially resolved photoluminescence of the quantum wires was observed by using microscopic photoluminescence (μ-PL) measurement at 70 K. We estimated the electron temperature from the μ-PL spectra in quantum well and wire. As a result, the spatial fluctuation of the electron temperature in the quantum wire was shown.

By analysing exciton binding energies, we have experimentally investigated static dielectric constant of GaInNAs. Contrary to conventional semiconductors, it was found that both static dielectric constant and bandgap decrease by adding nitrogen.

Sites for Cys substitutions to form a disulfide bond were chosen in subtilisin E from Bacillus subtilis, a cysteine-free bacterial serine protease, based on the structure of aqualysin I of Thermus aquaticus YT-1 (a thermophilic subtilisin-type protease containing two disulfide bonds). Cys residues were introduced at positions 61 (wild-type, Gly) and 98 (Ser) in subtilisin E by site-directed mutagenesis. The Cys-61/Cys-98 mutant subtilisin appeared to form a disulfide bond spontaneously in the expression system used and showed a catalytic efficiency equivalent to that of the wild-type enzyme for hydrolysis of a synthetic peptide substrate. The thermodynamic characteristics of these enzymes were examined in terms of enzyme autolysis (t1/2) and thermal stability (Tm). The half-life of the Cys-61/Cys-98 mutant was found to be 2-3 times longer than that of the wild-type enzyme. Similar results were obtained by differential scanning calorimetry. The disulfide mutant showed a Tm of 63.0 degrees C, which was 4.5 degrees C higher than that observed for the wild-type enzyme. Under reducing conditions, however, the characteristics of the mutant enzyme were found to revert to those of the wild-type enzyme. These results strongly suggest that the introduction of a disulfide bond by site-directed mutagenesis enhanced the thermostability of subtilisin E without changing the catalytic efficiency of the enzyme.

We have investigated the temperature dependence of midinfrared optical absorption in germanium under intense free-electron laser fields. We observed that the absorption decreases as temperature decreases. We find that the temperature dependence of the absorption is consistent with calculations based on the Keldysh theory, in which the temperature dependence of the direct-gap energy of germanium is considered.

We have investigated the effects of high-power laser pulses on a transparent material using a free-electron laser (FEL). We have measured optical transmittance through a germanium crystal in the midinfrared region, $\ensuremath{\lambda}=5.3--12.4\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{m}$ at room temperature. In spite of the fact that germanium is transparent in the midinfrared region, we have observed strong suppression of optical transmission under high-intensity FEL excitation.

A novel process technology has been developed to fabricate an EEPROM embedded CMOS VLSI. The new technique utilizing a single poly-Si EEPROM cell reduces process steps by 25% as compared with the conventional double poly-Si EEPROM cell. The EEPROM-embedded CMOS LOGIC LSI can be shrunk over future technology generations by introducing three kinds of gate oxide thickness. A widely operating voltage ranging from 1.5 V to 6.0 V and a standby current below 100 nA have been achieved.

Summary form only given, as follows. This study presents fabrication of nano-structured Ti-DLC films using arc-glow hybrid plasma. A deposition apparatus consists of a DC plasma torch, a substrate holder and a vacuum chamber. An orifice of 10 mm diameter mounted at the exit of the torch can generate pressure difference between the torch and the chamber. The chamber is evacuated by a dry pump of 5,000 L/min. The orifice and the large-scale vacuum pump enable to keep the pressure in chamber at 20 - 100 Pa, even if the pressure in the torch is 1 atm. The torch employs hollow cathode made of Ti, the Ti is evaporated by the arc discharge, and then sprayed onto the substrate with a plasma jet. The pressure in chamber is low enough to generate a glow discharge. The 13.56 MHz RF power supply is connected to the substrate holder to generate a glow discharge plasma as well as to add a negative bias on the substrate. Deposition of Ti-DLC films were performed using C/sub 2/H/sub 2/ and CH/sub 4/ as the reactant gases. SEM observation and EDAX analysis results suggest that the film includes not only nano-size (i.e. 1-50 nm) Ti particles but also large droplets in carbon matrix. The carbon matrix was assured as DLC according to Raman spectroscopy. The swirl flow generator was adopted to reduce the droplets, it was found that most of droplets were eliminated when C/sub 2/H/sub 2/ was supplied into the plasma torch together with Ar in the swirl flow. The hardness of the deposited film increased from 13 to 30 GPa with decreasing the Ti content in the film from 0 to 30 vol.%. The thickness of the film was approximately 5 um in 1 h deposition and the friction coefficient was 0.3 against stainless steel ball. The residual stress seems to be decreased by the dispersed Ti nano-particle.

Different degradation modes were observed under high and low reverse stress current conditions. The temperature dependence of the gradation was studied, and it was found that the degradation is greatest around 50 degrees C. The mechanisms of the degradation and its recovery were also investigated, using MOS structures and simulation. MOSFET evaluation indicated that electron trapping and interface state generation occur during the stress. Simulation confirmed that the degradation is caused mainly by the interface states generated in the oxide near the emitter-base junction. >

Three samples with different thicknesses of polysilicon-silicon interfacial oxide were prepared. The influence of the interfacial oxide on the electrical characteristics of 0.8- mu m BiCMOS VLSIs was studied. From the results, the maximum interfacial oxide thickness allowed for BiCMOS LSIs was determined. To control the interfacial oxide thickness, the ball-up mechanism was studied using HRXTEM combined with energy-dispersive X-ray spectroscopy measurements. The optimum heat treatment after emitter deposition to realize 0.5- mu m BiCMOS VLSI was also determined. >

A new model for Monte Carlo simulation is proposed for one-dimensional electron gases. In the model, electron energy and momentum are treated as independent variables, and the Wigner distribution function f(k, omega ,t) is simulated instead of the semiclassical distribution function f(k,t). Using this method, the transport responses of one-dimensional electron gases in a quantum wire at room temperature are evaluated in which electrons are interacting with optical phonons only, and the results reveal that the electron temperature increases monotonically with applied electric field without showing anomalous carrier cooling.

A 0.5- mu m BiCMOS technology for achieving speed performance with scaling is described. For the lower supply voltage of 3.3 V, the delay time of the conventional BiCMOS gate becomes almost equal to that of the CMOS gate. A BiNMOS circuit was employed and achieved a speed advantage over the CMOS at 3.3 V. To improve bipolar performance and its ECL (emitter coupled logic) gate delay time, a selectively ion-implanted collector technology, was investigated and a quasi-self-aligned bipolar transistor with double polysilicon layers was utilized. The ECL gave achieved a delay time of 57 ps/stage. Both gates retained the speed performance for the scaling trend. >

The current gain of a bipolar transistor, h/sub FE/, is degraded by the emitter-base reverse-bias stress. The mechanism has been interpreted to be due to an increase in the interface state density, while its dependence on stress time has been found to be proportional to t/sup n/, where n is 0.5 to 1. It was expected that if the stress time was long enough, the increase in interface state density would saturate to a maximum value. However, an anomalous time dependence of base current increase-a slower increase initially followed by a rapid increase in the intermediate stage-was found for bipolar transistors whose junction surface was oxidized in dry ambient conditions. This is explained by the hypothesis that the potential distribution is modulated by the charge in the oxide or at the interface. >

Highly injected intrinsic base potential was directly measured by using a novel test structure. Measured distribution of the intrinsic base gives useful information for investigation of the high-injection operation of a bipolar transistor. Using this method the effect of base dose (current gain) on emitter crowding was investigated. In general, a knee current, which is defined as the collector current when h/sub FE/ becomes one-half of its maximum value h/sub FE0/, increases as the base dose increases. However, it was observed that the knee current saturated when the base dose was high. From the measurement results, it was clarified that this phenomenon is due to the emitter crowding effect. >