Photoirradiation effects on the polymer light-emitting devices (PLEDs) with a semitransparent-Al cathode have been studied. A light-emitting polymers, a poly (p-phenylene vinylene) derivative MDOPPV has been used in this study. Upon photoirradiation, the emission intensity at a constant voltage was rapidly decreased. However, the quantum efficiency of electroluminescence remained constant, indicating the spatial separation between recombination zone and photooxidized defects. On the other hand, the quantum efficiency of photoluminescence rapidly dropped upon similar photoirradation. These can be understood by taking the difference in the spatial distribution and the origin of excitons between electro- and photo-luminescence processes. It was also found that the photooxidation rate of the polymer film whose thickness is ca. 100 nm does not have thickness dependence, suggesting that the photooxidation of the polymer proceeds uniformly throughout the device.

Organic light emitting diodes (OLEDs) containing nanostructured cathode buffer layers were fabricated, and their electrical and emitting properties were investigated. The OLEDs have an ITO anode/CuPc/TPD/Alq3/buffer layer/Al cathode structure with the buffer layers made from nanostructured alternating layers Alq3 and Al. The driving voltage and the efficiency of the devices were improved by insertion of the buffer layer. It was estimated that some modulations of the Schottky barrier at the Alq3 and the Al cathode interface were induced due to the insertion of the buffer layer and it caused an enhancement of electron injection from the Al cathode.

We proposed the conduction mechanism of organic light-emitting diode (OLED) using a one-dimensional discontinuous model. We assumed that each emitting molecule corresponds to a hopping site according to the actual charge transfer between adjacent molecules. Both carrier mobility of Alq3 and barrier heights for each carrier were derived from experimental data. We calculate transient behavior of carrier, field, and exciton distribution. Both carrier injections assumed the Schottky injection. In the previous results, when we assumed that calculated current density fit the experimental one in the current density field curve, calculated light-emission intensity did not fit the experimental one in the light-emission field curve. Furthermore, the slope of the calculated light emission-field curve is too small to fit the experimental one. In the previous study, hopping distance was assumed to be 1 nm. In this study, it is assumed to be 1.7 nm. We consider that field dependence of electron injection is too weak to explain only the Schottky emission. When the electron injection is assumed to be both Schottky emission and Fowler-Nordheim emission calculated light-emission field as well as the current-density field curves were fit to the curve of each experimental characteristics.

The optical pulses of 50 MHz has been obtained from an organic light emitting diode (OLED) based on the Alq₃ emissive layer with the active area of 0.01 mm². We demonstrate that the OLEDs can be applied to fields of optical communication as the electro-optical conversion device for transmitting the signals of moving picture.

The threshold voltage of Coulomb staircase using organic molecules was analyzed by extending our previous model with only consideration of the metal/organic film interfacial space charge to the generalized one. The generalized model is helpful to examine coupling capacitance in organic double barrier tunneling junction (DBTJ). The current-voltage (I-V) characteristic of metal/polyimide (PI)/rhodamine-dendrimer (Rh-G2)/PI/metal junction was analyzed using this generalized model. The calculation results were in good agreement with our experimental data.

Metal nanostructure of organic/metal interface showing photocurrent multiplication phenomenon more than 10⁵-fold was investigated. Au films deposited on organic films were revealed to be a gathering of nanoparticles and the multiplication rate can be tuned by the particle size. Spatial gaps formed between Au sphere and organic surface, which provide the hole accumulation sites (structural trap), was concluded to be indispensable for the photocurrent multiplication.

We have developed the new energy storage system utilizing a radical redox reaction of poly (2,2,6,6-tetramethylpiperidinoxy methacrylate), PTMA. The coin-type cell with PTMA cathode demonstrates the charge capacity of is 72 Ah/kg, which corresponds to 65% of the theoretical capacity, and the coulombic efficiency was 90% in first charge-discharge cycle. The results indicate that the stable polyradical cathodes are promising materials due to their high charge utilization and the possibilities for the wide diversity of molecular design.

Organic nonlinear optical crystal 4-(p-dimethylaminostyryl)-1-methylpridinium tosylate (DAST) has a larger electro-optic (EO) coefficient than that of LiNbO₃ crystal. Thus, DAST is a promising material for EO switching device. To use its large EO coefficient effectively, a waveguide structure is desirable. We have successfully fabricated two types of DAST crystal optical channel waveguide. One is a serially grafted waveguide combining a DAST and a transparent polymer by using the combination of standard photo-process and reactive ion-etching (RIE). Because DAST has large optical loss, parts of the waveguide should be composed of transparent polymer with a serially grafted structure with DAST. This structure reduced not only a propagation loss but also input/output losses. This serially graft waveguide fabrication technique for active organic crystal is available to many types of crystals with device function. The other is a channel waveguide made by a photo-bleaching technique. The cladding part of DAST waveguide was photo-bleached by irradiation of UV light. Under and over cladding layer were composed with UV-cured resin that did not dissolve the DAST crystal. This technique is very convenient for making DAST waveguide because of its simple procedure to make core-cladding structure of DAST compared to standard photo-process and RIE.

We have developed a 22 digital optical switch (DOS) composed of four 12 DOS elements and a thermo-optic wavelength tunable filter using silicone resin waveguides. The 22 DOS operated with a switching power of 380 mW, a very low crosstalk of less than -60 dB, and a low insertion loss of less than 2.5 dB at 1.55 µm. We have also developed two types of polymer thermo-optic wavelength tunable filter with a pair of triangular phase shifters. One filter is designed for a large-scale WDM system (32 channels, 0.8 nm spacing) and the other for a small-scale WDM system (10 channels, 0.8 nm spacing). We optimized the arrayed waveguide number, reducing the operating power required by these filters. Moreover, they both operated with a low crosstalk of < -25 dB.

Polyurea thin films containing azo-based nonlinear optical (NLO) chromophore were prepared by co-deposition of 4,4'-diphenylmethane diisocyanate and 2,4-diamino-4'-nitroazobenzene monomers using the ionization-assisted method. The co-deposited film reacted to form polyurea after annealing in the air. The dichroic optical absorption spectra indicated the preferential orientation of dipole moments in the as-deposited film. The substrate bias voltage influenced the optical anisotropy. Maker fringe measurement showed that the films have NLO activity without the poling process.

The adsorption behavior of cytochrome c was investigated using slab optical waveguide (SOWG) absorption spectroscopy at the near ultraviolet region utilizing thin quartz plates as planar waveguides. SOWG absorption spectra of cytochrome c measured at constant time intervals showed significant influence of surface hydrophilicity and solution chemistry on the adsorption of this important heme protein in quartz surface. Being polar and typically amphoteric, the protein preferred adsorption on hydrophilic surface than on hydrophobic surface as implied by the lower absorbance data obtained in the latter than in the former. At lower ionic strength and in the absence of buffer, the protein molecules tend to adsorb on the quartz surface. Plots of near steady-state absorbance versus protein concentration follow hyperbolic pattern in the absence of buffer or at low ionic strength and become more linear as the buffer concentration is increased. The results presented here are explained in terms of the general qualitative understanding of protein adsorption at solid-aqueous interfaces and further aids in elucidating the properties of protein monolayers and films.

Angle-multiplexed holography using four-wave mixing (4WM) was demonstrated with a monolithic photorefractive carbazole trimer. We measured the diffraction efficiency as a function of incident angle of the read beam. The cross-talk was almost negligible at the Bragg angle mismatch of 1. Two figure images were recorded with the different incident angle of the reference beam in the photorefractive carbazole trimer film, and were read out independently by illuminating with the read beam which counter-propagated to the corresponding reference beam.

The optical recording on an azopolymer surface by the optical fiber probe with a 100 nm diameter aperture was demonstrated. The 150 nm diameter pit was formed by the optical fiber probe coupled with a 50 ns pulse of 10 mW and 488 nm wavelength coherent light.

A study of apple flavor, banana flavor, and their chemical components was performed using an array of quartz crystal microbalance (QCM) gas sensors coated with sensing films such as lipids or stationary phase materials for gas chromatography (GC). The steady state sensor responses measured by a static measurement system were used to evaluate the characteristics of the different samples by principal component analysis (PCA) method. Since the array has shown good discrimination properties for fruit flavor components providing useful information, it was used to investigate the components that primarily contribute to the odor of the flavors. The results obtained from principal components analysis aided by sensory test were also used for an attempt to synthesize apple and banana flavors using only three of its odor components.

The mesoporous materials from the self-assembled organic-inorganic compound materials have great possibilities for a variety of applications. However, to make use of these kinds of materials effectively, they must be controlled. In this paper, we are succeeded in powder state pore size control and in significantly fabrication film state for device application use.

Self-ordered mesoporous silicate films from organic-inorganic compound materials are successfully fabricated into the surface photo voltage (SPV) type gas sensor device as a gas adsorption insulator layer. These kinds of gas sensors device exhibit NO gas sensing property dependent on their mesoporous film structure. We are succeeded in indication about a possibility of mesoporous silicate film for the SPV type gas sensor application.

We investigated the electrical properties of hole transport materials such as TPD, α-NPD and m-MTDATA using in-situ field effect measurement. TPD, α-NPD and m-MTDATA films showed p-type semiconducting properties, and their electrical parameters such as conductivity, carrier mobility and carrier concentration were obtained. We also examined the effect of the substrate temperature during vacuum deposition and the thermal treatment after deposition, on the electrical parameters of the films. Experimental results showed that conductivity and carrier mobility decreased as the substrate temperature increased over the glass transition temperature. These decreases in conductivity and carrier mobility as a result of thermal treatment appear to be strongly related to the degradation mechanism of organic electroluminescent devices.

Digitalization in electronic systems requires the electronics devices in de-coupler sets with low impedance at high frequency, and high reliability. A shield strip type line component with aluminum substrate, its surface oxidized dielectric layer and a conducting polymer electrolyte has been developed. The conducting polymers of polypyrrole and poly(3,4-ethylenedioxythiophene) have been formed by direct chemical oxidative polymerization and electrochemical polymerization on a dielectric layer. Thus, the surface of the dielectric layer is covered with conducting polymer films. The structure of the line component is strip line conformation just like a crushed coaxial cable with in-put and out-put terminals surrounded by the conducting polymer electrolyte. Two types of the components, i.e., a large surface area, 10 20 mm, and a small surface area, 4 4 mm, have been fabricated with polypyrrole and poly(3,4-ethylenedioxythiophene), respectively. The dielectric properties of these line components have been investigated with a Impedance/Gain-phase analyzer and a network analyzer. Due to the high conductivity of the polymer electrolytes, the line components demonstrate low impedance at resonance frequency. Regarding the frequency characteristics of the line components, the impedance and ESR at high frequency are lower than those of the conventional capacitors. Furthermore, the transfer coefficients, S₂₁, are three orders lower than those of other capacitors in a wide frequency band from 10 kHz to 6 GHz. The results indicate the excellent characteristics of the line components for the power line de-coupler set at the boundary of the closed circuit unit.

STM/STS measurements have been carried out for TTF-TCNQ complex films evaporated on hydrogen-terminated silicon substrates, and the variation of tunneling spectra has been investigated on morphologically different crystal grains. Very thin semiconductive adsorbed layers were found to cover the as-deposited film surfaces. By removing the adsorbed layers, the intrinsic electronic structures of two different phases were revealed. A 'needle phase' which appears at the early stage of film growth has a semiconductive character and a 'granular phase' which grows later has a metallic character similar to bulk crystals. The electronic structure of the needle phase is considered to be affected by the substrate although the crystallographic structure is similar to the bulk crystal of TTF-TCNQ.

The surface potential built across vacuum deposited phthalocyanine (Pc) films on aluminum electrode was investigated by means of electro-modulation spectroscopy. The sandwich-type cells with thin air gap, which becomes a good insulator were used in order to avoid the influence of charge injection. The existence of the surface potential at the metal/organic-material interface induced 1f referenced electro-reflectance (ER) signals. As a result, the surface potential built across vacuum deposited Pc films on aluminum electrode was estimated to be 1.25 V.

The prospects of electron spectroscopy of working organic electronic device structures are discussed. The experimental consideration and the result of actual measurement are presented.

Carbon-gold (C-Au) film was formed by co-operation process of plasma CVD and sputtering with using methane and Ar mixture gas and gold plate discharge electrode. Refractive index of 3.1 for the film was obtained at Au atom content of 5.5 atomic%. The optical transmittance was improved significantly in the visible light wavelength range compared to the C-S-Au film reported previously. Au atom distribution in the C-Au film and the electronic polarizabilities were discussed in the relation to the refractive index.

We developed a novel model for degradation of remanent polarization resulting from repeated polarization reversal cycling. The characteristics of ferroelectric capacitors have been simulated with the double saturation function model that required only five parameters; E_c, Q_rmax, Q_dmax, K_r and K_d. This novel model combines an equivalent gap capacitor with the double saturation function model. The model predicts hysteresis loops under endurance conditions. The simulated results are well in agreement with the results obtained in the experiment. The model is utilized to quantify the degradation effect of remanent polarization on ferroelectric memory applications.

The radix-64 encoding scheme was used to reduce the number of partial products in the 5454 CMOS parallel multiplier. The transistor counts, the chip area and the power-delay product were reduced by 28%, 22%, and 17%, respectively, compared to any of the published 5454 CMOS parallel multipliers. A redundant binary (RB) number system was used to represent any of the 65 multiplying coefficients as a RB number which consists of two of 9 fundamental multiplying coefficients and their complements. The resultant RB partial products were added by using optimized RB adders. The total transistor count of the proposed multiplier was 43,579. The chip area in 0.25 µm CMOS process with 5 metal layers was 0.99 mm². The power consumption and the multiplication time were 111 mW and 6.9 ns, respectively.

This paper describes a CMOS transponder IC for RFID applications. A full-wave rectifier implemented using NMOS transistors supplies the transponder with a dc supply voltage. A 64-bit ROM has been designed for a data memory. Front-end impedance modulation and Manchester coding are used for transmitting the data from the transponder memory to the reader. A new damping circuit has been proposed and employed for impedance modulation. The designed circuit has been fabricated using a 0.65 µm 2-poly, 2-metal CMOS process. Measurement results show that it has a constant damping rate of around 20-25% and a data transmission rate of 3.9 kbps at a 125 kHz RF carrier. Die area is 0.9 mm0.4 mm. The measured reading distance is up to 7 cm.

A drain avalanche hot carrier lifetime model including a body effect caused by secondary hot electrons has been developed. It has been confirmed that the proposed model fits a wide range of experimental data using a small number of parameters. The model provides a practical modeling methodology for reliability simulation based on parameter extraction at maximum substrate current conditions alone. Simulation accuracy produced by the methodology has been experimentally verified using ring oscillators including NAND gates. It has been demonstrated that simulation accuracy of degradations has become by 0.34 decade better using the new methodology than using that based on the conventional τI_d/W-I_sub/I_d model.

To understand the characteristics of a multimedia service, such as the large volume of data transfer and real-time constraints, it is necessary to have a performance evaluation tool for an HDD. Our HDD simulator is running on a PC operated on FreeBSD UNIX OS. We first investigate the seek time and the sustained rate of HDDs and then evaluate the performance of an HDD for an experimental VOD system. Applying the experimental results, we find the bottleneck of an HDD, and then suggest what HDDs are to be selected for a VOD system.

A new type of electromagnetic vibration transducer for use in an IME (implantable middle ear) system is presented and evaluated by in-vitro experiment. Because the new designed transducer includes two magnets glued together with the same pole facing inside the coil, it can reduce the interference from an environmental magnetic field. And the proposed transducer exhibits a high vibration efficiency and wide frequency response. Using dead human's temporal bone, in-vitro experiments were carried out and the results showed that the proposed vibration transducer will be properly used to implantable middle ear for mild to severe hearing loss patients.

A uni-traveling-carrier refracting-facet photodiode, a short-stab bias circuit, and a patch antenna are monolithically integrated to make a compact and low-cost photonic millimeter-wave emitter for fiber-radio applications. The device emits the maximum effective radiation power of 173 dBm at 60 GHz including a directive gain of the patch antenna.