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This paper describes performance characteristics of a bridge‐connected magnetic circuit with single output winding in dc control. The difference between positive and negative amplitudes of output current changes with the dc control current. An application of the bridge‐connected magnetic circuit to a dc current detector is presented in this paper.

This paper discusses two new kinds of micromagnetoelastic devices made on silicon wafer whose function is to control the permeability of magnetostrictive soft magnetic thin films by voltage-controlled elastic strain. One is piezoelectric type and the other is electrostatic type. Structure, fabrication process, characteristics, and maximum possible output are discussed. The feasibility of these devices has been clarified although the rate of obtained permeability change was less than 1%. These device characteristics could be improved to 11% for piezoelectric type and to 80% for electrostatic type by the optimization of device dimensions and reduction of process damage to the magnetic film.

InAs quantum dots (QDs) grown on InP substrates can be used as light emitters in the telecommunication bands. In this paper, we present optical characterization of high-density circular quantum dots (QDots) grown on InP(311)B substrates and elongated dots (QDashes) grown on InP(001) substrates. We study the charge carrier transfer and luminescence thermal quenching mechanisms of the QDots and QDashes by investigating the temperature dependence of their time-integrated and time-resolved photoluminescence properties. This results in two different contributions of the thermal activation energies. The larger activation energies are attributed to the carrier escape to the barrier layer and the wetting layer (WL) from QDots and QDashes, respectively. The smaller activation energies are found to be originated from inter-dot/dash carrier transfer via coupled excited states. The variation of the average oscillator strength associated with the carrier re-distribution is discussed. The relation of the two activation energies is also quantitatively studied with the measurements of excited-state and ground-state energy separations. Finally, we show an approach to isolate individual quantum dots or dashes in a suitable nanostructure.

We have found that molybdenum dioxide (MoO_2) is an excellent dopant for enhancing electrical conductivities in organic hole-transporting layers. We fabricated hole-only devices with an alpha-sexithiophene (α-6T) layer doped with MoO_2 at various concentrations to investigate how doping MoO_2 into the α-6T layers influences the hole-injection and hole-transport characteristics of these layers. We observed a marked increase in electrical conductivity as a result of the MoO_2 doping. The 30-mol % MoO_2-doped α-6T layer had a high electrical conductivity of 8.9±1.3×10^ S/cm. From the results of our visible/near-infrared absorption spectra study of these doped layers, we confirmed that this increase in electrical conductivity is caused by a charge transfer between MoO_2 and α-6T, which leads to an increase in free hole concentration in the doped layers and the formation of an ohmic contact at an electrode/α-6T interface. In the latter part of this paper, we discuss current flow and electroluminescence (EL) characteristics of organic light-emitting diodes (OLEDs) with a 30-mol % MoO_2-doped α-6T hole-transporting layer and a 30-mol % Cs-doped phenyldipyrenylphosphine oxide (POPy_2) electron-transporting layer. We achieved an extremely low driving voltage of 3.1 V required for a current density of 100 mA/cm^2 in the doped OLEDs owing to the use of the α-6T and POPy_2 layers with high carrier mobilities and the excellent p-type MoO_2 and n-type Cs dopants. We demonstrated the enhancement of power efficiencies by ≈2 times in the doped OLEDs compared with undoped OLEDs and observed bright EL at low driving voltages in the doped OLEDs, for example, 100 cd/m^2 at 2.3 V, 1000 cd/m^2 at 2.7 V, and 10 000 cd/m^2 at 3.3 V.

This paper demonstrates that the spatial distribution of electronic states of an arsenic ion implanted Si (111) substrate can be observed by using a wavelength tunable second harmonic (SH) microscope in a wide photon energy range from 2hω=1.96 to 5.19 eV. The contrast in the SH intensity images between the As-doped area and the nondoped area depends greatly on the SH photon energy. For 2hω>3 eV, optical second harmonic generation (SHG) from the nondoped area was stronger than from the doped area, and the contrast was reversed for 2hω

This paper describes a two c‐core type orthogonal‐core made of Fe‐6.5 wt. % Si sheet and its application to power converters. The orthogonal‐core can be used in the high‐frequency region because a Fe‐6.5 wt. % Si sheet has superior soft magnetic properties including high permeability and low core loss. Using the orthogonal‐core, we constructed a parametric oscillation type dc‐ac converter. The dc‐ac converter had voltage regulation, overload protection, noise rejection, and almost sinusoidal output. Good efficiency was obtained in the frequency range from 400 Hz to 1 kHz. Furthermore, we propose a dc‐dc converter for coupling two independent dc power sources. The dc‐dc coupling converter has bilateral power transfer and ease of controlling the transferred power. The basic operation of the dc‐dc coupling converter is described.