2D-numerical analysis and optimum design of thin film silicon solar cells

Device modeling for p–i–n junction μc-Si basis thin film polycrystalline Si solar cells has been examined with a simple model of columnar grain structure and its boundary condition utilizing two-dimensional device simulator. As the simulation results of solar cell characteristics show, open-circuit voltage (V_oc) and curve fill factor (FF) considerably depend on those structural parameters, while short-circuit current density (J_sc) is comparatively stable by courtesy of homogeneous built-in electric field in the i layer. It has also been found that conversion efficiency over 12% could be expected with 1 μm grain size and well-passivated condition with 3 μm thick i-layer.     

Characterization and inventory of PCDD/Fs and PBDD/Fs emissions from the incineration of waste printed circuit board

Many developing countries have not significantly changed their course with regard to electronic waste contamination, and they are still facing the specter of mountains of hazardous electronic waste, with serious consequences for both the environment and public health. An efficient and stable analytical method was developed to determine the inventory and emission factors of polybrominated dibenzo-p-dioxin and dibenzofurans (PBDD/Fs) and polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs) formed from the incineration of scrap printed circuit boards (PCBs). Both PBDD/Fs and PCDD/Fs have been found in all experimental sections with a maximum formation rate at temperatures between 250 and 400 °C. The amounts tended first to increase and then began to decrease as the temperature rose. When subjected to a heating temperature of 325 °C, the total content of twelve 2,3,7,8-substituted PBDD/Fs congeners (tetra- through octabromo-) gathered from three outputs was the largest, at 19?000, 160?000, and 57 ng TEQ/kg in solid, liquid, and gaseous fractions, respectively; the total content of seventeen 2,3,7,8-substituted PCDD/Fs congeners (tetra- through octachloro-) was 820, 550, and 1.4 ng TEQ/kg. The formation of PCDD/Fs was remarkably less than that of PBDD/Fs because bromine concentrations considerably exceeded chlorine concentrations. The ingredients and conditions necessary to form PCDD/Fs or PBDD/Fs were definitely present, such as products of incomplete combustion, halogenides, an oxidizing atmosphere, and a catalyst-Cu salts being the most effective, significantly increasing the yields of PCDD/Fs and PBDD/Fs and decreasing the optimum temperature range.     

Widely tunable multichannel wavelength conversion using multiple wavelength quasi-phase-matched LiNbO/sub 3/ waveguide

Widely tunable multichannel wavelength conversion using a multiple wavelength quasi-phase-matched LiNbO/sub 3/ waveguide is proposed. Simultaneous conversion of four-channel signals with a tunable range of more than 35 nm is successfully demonstrate for the first time.     

A new leakage mechanism of Co salicide and optimized processconditions [for CMOS]

We have clarified a new leakage mechanism in Co salicide process for the ultrashallow junctions of 0.1-μm CMOS devices and revealed the optimum Co salicide process conditions for minimizing the leakage current. We found that leakage currents flow from many localized points that are randomly distributed in the function area. We successfully verified our localized leakage model via Monte Carlo simulation. We identified abnormal CoSi_x spikes under the Co silicide film, as being the origin of the localized leakage current. These CoSi_x spikes grow rapidly only during annealing between 400 and 450°C for 30 s when Co₂Si phase is formed. These spikes never grow during annealing at over 500°C, and decrease with high temperature annealing. A minimum leakage current results by optimized annealing at between 800 and 850°C for 30 s. This is because a trade-off exists between reducing the CoSi_x spikes and preventing the Co atom diffusion from Co silicide film to Si substrate, which begins at annealing above 900°C     

An 0.1-μm voidless double-deck-shaped (DDS) gate HJFET withreduced gate-fringing-capacitance

This paper describes a novel double-deck-shaped (DDS) gate technology for 0.1-μm heterojunction FETs (HJFETs) which have about half the external gate fringing capacitance (C_f^ext) of conventional T-shaped gate HJFET's. By introducing a T-shaped SiO₂-opening technique based on two-step dry-etching with W-film masks, we fabricated 0.1-μm gate-openings which were suitable for reducing the C_f^ext and filling gate-metals with voidless. The fine gate-openings are completely filled with refractory WSi/Ti/Pt/Au gate-metal by using WSi-collimated sputtering and electroless Au-plating, resulting in high performance 0.1-μm DDS gate HJFETs are fabricated. The 0.1-μm n-Al _0.2Ga_0.8As/i-In_0.15Ga_0.85As pseudomorphic DDS gate HJFETs exhibited an excellent V_th standard-deviation (σV_th) of 39 mV because dry-etching techniques were used in all etching-processes. Also, an HJFET covered with SiO₂ passivation film had very high performance with an f_T of 120 GHz and an f_max of 165 GHz, due to the low C_f^ext with the DDS gate structure. In addition, a high f_T of 151 GHz and an f_max of 186 GHz were obtained without a SiO₂ passivation film. This fabrication technology shows great promise for high-speed IC applications     

A review of studies on the electric field and the current induced in a human body exposed to electromagnetic fields

How high an electric field or current is induced inside a human body when exposed to an electromagnetic field has recently attracted much attention. The background for this is twofold; concern about the possible health effects of electromagnetic fields (usually called ‘EMF issues’), and their positive application to medical treatment or new research subjects. This paper reviews various aspects related to this topic in terms of the following items: basic formulas for field calculation, effect of electromagnetic fields, calculation methods, an Investigation Committee in the IEEJ, and future research subjects. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

A review of studies of the biological effects of electromagnetic fields in the intermediate frequency range

Concerns have been raised regarding the relationship between electromagnetic fields and human health. Compared to the research on extremely low frequency (ELF) and radio frequency (RF) electromagnetic fields, very few studies have addressed the biological effects of the electromagnetic field with intermediate frequency (IF) from 300 Hz to 10 MHz. This paper reviews the biological effects of IF electromagnetic fields with around 20 kHz from in vivo and in vitro studies. In contrast to studies on the effects of ELF and RF electromagnetic fields, few studies on biological effects of IF elecromagnetic fields have been carried out. From a short review based on published articles, it is seen that the available research data is inadequate for health risk assessment of IF electromagnetic fields. In future, it will be very important to conduct biological effects studies and evaluate the effects on human health from exposure to IF electromagnetic fields. © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

In-situ plasma spraying: Alumina formation and in-flight particle diagnostic

In-situ plasma spraying (IPS) is a promising process to fabricate composite coatings with in-situ formed thermodynamically stable phases. In the present study, mechanically alloyed Al-12Si and SiO₂ powder was deposited onto an aluminum substrate by atmospheric plasma spraying (APS) to obtain a composite coating consisting of in-situ formed alumina reinforced hypereutectic Al-18Si matrix alloy. The effects of spray parameters (arc current and spray distance) and in-flight particle characteristics (temperature and velocity) on in-situ reaction intensity (alumina and silicon) have been investigated. The results show that, in-situ alumina formation and silicon intensity strongly depend on in-flight particle characteristics, spray distance and substrate temperature.     

Synthesis of 1,3-Oxazines and Furo[2,3-b]pyrans by reaction of 2-amino-4,5-dihydro-3-furancarbonitriles with dibenzoyldiazomethanes

2-Amino-4,5-dihydro-3-furancarbonitriles ( 1 ) react with a slight excess of dibenzoyldiazomethane in the presence of rhodium(II) acetate to give 1,3-oxazin-4-ones ( 2 ). With three equivalents of dibenzoyldiazomethane compounds 1 react to afford furo[2,3-b]pyran-3a-carbonitriles ( 3 ). Compound 3a was also obtained by treatment of 2a with two equivalents of dibenzoyldiazomethane.     

Formation mechanism of shish in the oriented melt (II)—two different growth mechanisms along and perpendicular to the flow direction

In part 1 of this series of paper, we have solved the formation mechanism of shish from the oriented melt based on the kinetic observation. In this work, we have shown for the first time the molecular mechanism of the growth of shish by kinetic study. We found that there are two different type of the growth of shish against the flow direction. The growth rate along the flow direction (U) is proportional to ΔT, where ΔT is the degree of supercooling. This indicates that U is mainly controlled by the rearrangement process of the chain near the end surface of the shish. On the other hand, the growth rate perpendicular to the flow direction (V) obeyed a well-known equation V∝exp(−B/ΔT), where B is a constant proportional to the free energy necessary for forming a critical secondary nucleus ΔG*. This indicates that V is mainly controlled by the secondary nucleation process on the side surface of shish. Moreover, we also found that there is a critical shear rate for the growth of shish. Below , U and V approached to zero and the growth rate of spherulite, respectively. From this experimental fact, we proposed that the chain conformation near the interface between the melt and shish, i.e. near the end and side surface of shish is elongated and oriented by the shear flow above .