External DC Voltage Research Articles

特集 超薄膜の構造と機能 有機高分子非線形光学材料：最近のトピックス

The present review is mainly concerned with the macromolecular organic nonlinear optical materials for frequency doubling. Organic polymer materials are expected to apply the optical devices for the transparent, easy processability and so on. Recently some studies were carring out about the polymer, chromophore and device structures. These topics are introduced in this review. One of the major problems for poled polymer systems is the lack of thermal stability after aligningchromophore units. In order to prevent the decay, some ferroelectric or crosslinkable polymers carrying chromophore moiety were prepared. They showed large d coefficients and stability. Previously, the chromophores having shorter absorption wavelength band than the harmonic wavelength have been used. However, it has made possible to apply the longer absorption wavelength chromophores by using Cherenkov type phase matching. Besides, it has reported that the novel two-directional charge transfer molecules possessed large off-diagonal, β components has shown a small decay of d 33 even when the order parameter has relaxed. In optical waveguide structure, quasi phase matching accomplished by periodically poled or bleached waveguide structure was effective method to obtain harmonic light. As the practical and adroid method to achieve phase matching in waveguide, a attempt was made to adjust and suppress the phase matching condition by continuing to apply external dc voltage during frequency doubling. The guide-layer made of low Tg polymer was effective for quick response of chromophore alignment and change of refractive index against external electric field.

Image amplification with local addressing by two-wave coupling in a Bi_12SiO_20 crystal by application of direct-current voltage

We present a proposal and an analysis of local image amplification by two-wave coupling in a Bi12SiO20 crystal by applying external dc voltage. The analogy of two-wave coupling to an optical transistor array is discussed. It is found through the experiments that the local gain in amplification is given not by the reference-beam pattern alone but also by the electric field that is formed by the local photoconductance of the Bi12SiO20 crystal. A resistance-network model is used for analysis of the electric-field distribution. A variety of experiments verify the theoretical and calculated analyses. A sample reference pattern for amplifying segments of a signal image is designed through the resistance-network analysis of the electric-field distribution.

General purpose three phase firing circuit for phase angle control applications

Phase angle control is a well established technique which is used in many applications involving fixed as well as variable voltage and frequency. In some applications the voltage is distorted. This leads to the need for a general purpose firing circuit which meets all of these requirements. This paper describes a simple and reliable three phase firing circuit that can be used in any phase angle application. This circuit can operate on a distorted and variable frequency supply. The firing angle of the three phases is linearly controlled by a single internal or external DC voltage which enables the circuit to be controlled by a microcomputer system. Another advantage of this circuit is the possibility of firing both thyristors and triacs.

Enhancement of neutron diffraction intensities from KTP single crystals with the application of a DC field

The anisotropic enhancement of neutron diffraction intensities from KTP single crystals with the application of an external DC voltage along its c-axis were investigated, and the similarity of this effect to that observed in α-LiIO3 crystals is discussed.

The selectivity of poly Si and SiO2 etching using a negative dc biasing of powered electrode

Abstract In this work the etch rates of poly Si and SiO2 in CCl4 plasma were investigated. The etch process in a planar flat-bed reactor was examined with the aim of controlling the selectivity by an external dc negative bias voltage. The pressure and rf current dependences of poly Si and SiO2 etch rates were obtained. For typical etch conditions, etch rates of about 120 nm min−1 and 25 nm min−1 for poly Si and SiO2 respectively have been achieved. The selectivity did not exceed a value of 5. It was shown the etch rate ratio (poly Si:SiO2) was dependent on dc voltage applied to the powered electrode. In order to achieve higher and more reproducible selectivity it is necessary to use a conducting bottom electrode and enhance the process chemistry.

Growth Mechanism of Silicon Plasma Anodic Nitridation

Nitridation of silicon was performed in a temperature range of 680°–920°C by 13.56 MHz RF oscillation in nitrogen‐hydrogen plasma. Growth kinetics and activation energy of nitridation were investigated. The relationship between nitridation time and nitrided film thickness was found to be . External dc voltage on plasma nitridation was effective in obtaining a high growth rate of nitrided film on silicon. Activation energy for the plasma anodic nitridation of silicon (0.25 eV) was twice as large as the value of plasma nitridation without an external dc voltage. The role of hydrogen in plasma nitridation was also studied with quadrupole mass spectroscopy.

Mineral interfacial processes in the method of induced polarization

A phenomenological laboratory investigation has been conducted of the IP response of pyrite, chalcopyrite, and chalcocite. The technique that was used is standard in electrochemistry and employs rotating disk electrodes. The effect of rotation is to stir the electrolyte and thus to restrict the maximum distance available for diffusion of electroactive aqueous species. For high rotation speed and low excitation frequencies, the mean diffusion length exceeds the thickness of the diffusion layer. The net effect is to reduce the electrode impedance at low frequency. The thickness of the diffusion layer and thus the impedance at low frequency can be controlled by the rotation speed. Measurements using rotating disk electrodes have been conducted in both the time domain and the frequency domain. For both pyrite and chalcopyrite, the results were the same: no dependence on rotation was observed. For frequency domain measurements with chalcocite, a strong dependence on rotation was observed. The interpreted diffusion layer thickness was found to depend on rotation speed to the [Formula: see text] power, in agreement with results predicted by hydrodynamic theory. The results of this study imply that there are two physical processes responsible for electrode polarization in the IP method. For chalcocite and perhaps other related copper sulfide minerals, the probable mechanism is diffusion of copper ions in the groundwater. In case, the phenomenon is correctly described by the Warburg impedance. Chalcocite’s distinctive response is thought to be related to its forming a reversible oxidation‐reduction couple with cupric ions in solution. No other common sulfide mineral forms a reversible couple with its cations in solution. For the other minerals of this study, the lack of dependence on rotation implies that diffusion of active species in the electrolyte is not the controlling process. Possible alternate mechanisms include surface controlled processes such as surface diffusion or adsorption phenomena. Ancillary data obtained during this study indicate the interface impedance of chalcopyrite is proportional to the electrode potential which in turn can be controlled by rotation speed, electrolyte composition, or application of an external dc current or voltage. This implies that the surface concentration of active species is dependent on electrode potential.

Low-distortion quadrature oscillator with photon-coupled FET control of amplitude and phase

A two-phase audio-frequency sine-wave oscillator consists of an integrator and an all-pass network in a closed loop. Photon-coupled FETs, which introduce no harmonic distortion, are employed as fine-tuning elements to stabilize amplitude and to set the frequency of oscillation. The circuitry guarantees that the two phases are in quadrature and that they have the same amplitude, which amplitude is proportional to an external DC voltage. Frequency can be synchronized, wilhout phase-shift, to an external clock.

Transient selection gates using breakdown

A new class of gates suitable for selection in memories is presented. The gate utilizes charge storage and avalanche breakdown to obtain a low power dissipation (~6/spl times/10/SUP -12/ J/selection, or ~60 /spl mu/W/gate in a 10-MHz-repetition selection rate), more than an order of magnitude below that of conventional TTL gates. Only narrow (/spl gsim/ 1 ns), nonoverlapping pulses are needed and external dc voltages are not required. A totally transient mode of operation is described that requires no resistors. Also described are the results of analog simulations using discrete components.

Anodic charge-carrier production in molten aromatics by triplet excitons

Intense irradiation of pure molten naphthalene, pyrene, and anthracene produces a photocurrent if an external dc voltage is applied. From the spectral response curve, which resembles closely the optical absorption curve in the region of the forbidden S0–T1 transition, we conclude that the photocurrent is due to excitation of the lowest triplet state. The excited state can produce charge carriers either when hitting a gold anode or by bimolecular annihilation within the bulk of the liquid. Evidence for cation formation at the anode is presented by observation of space-charge-limited currents and by the absence of this effect if the anode consists of nickel coated with an evaporated SiO2 layer. From the rise and decay time of the photocurrent the lifetime of the excited states can be determined. The values are 200 ± 100 ms for naphthalene and 40 ± 10 ms for pyrene. This lifetime decreases with decreasing spacing of the electrodes, indicating diffusion of the excited state to the electrodes where deactivation occurs. The diffusion coefficient of the excited state in naphthalene is (6 ± 2) × 10−2 cm2/s. This value and the estimated quantum yield for charge injection rules out any energy transfer involving molecular diffusion.