Junction capacitance reduction due to self-aligned pocketimplantation in elevated source/drain NMOSFETs

A new advantage of an elevated source/drain (S/D) configuration to improve MOSFET characteristics is presented. By adopting pocket implantation into an elevated S/D structure which was formed by Si selective epitaxial growth and gate sidewall removal, we demonstrate that the parasitic junction capacitance as well as the junction leakage was significantly reduced for an NMOSFET while maintaining its good short channel characteristics. These successful results are attributed to the modification of the boron impurity profile in the deep S/D regions. The capacitance reduction rate, furthermore, was more remarkable as the pocket dose was further increased. This means that the present self-aligned pocket implantation is very promising for future MOSFETs with a very short gate length, where high pocket dosage will be required to suppress the short channel effect     

Contribution of amino acid substitutions at two different interior positions to the conformational stability of human lysozyme

To elucidate correlative relationships between structural changeand thermodynamic stability in proteins, a series of mutanthuman lysozymes modified at two buried positions (Ile56 andIle59) were examined. Their thermodynamic parameters of denaturationand crystal structures were studied by calorimetry and X-raycrystallography. The mutants at positions 56 and 59 exhibiteddifferent responses to a series of amino acid substitutions.The changes in stability due to substitutions showed a linearcorrelation with changes in hydrophobicity of substituted residues,having different slopes at each mutation site. However, thestability of each mutant was found to be represented by a uniqueequation involving physical properties calculated from mutantstructures. By fitting present and previous stability data formutant human lysozymes substituted at various positions to theequation, the magnitudes of the hydrophobicity of a carbon atomand the hydrophobicity of nitrogen and neutral oxygen atomswere found to be 0.178 and –0.013 kJ/mol.Ų, respectively.It was also found that the contribution of a hydrogen bond witha length of 3.0 Å to protein stability was 5.1 kJ/moland the entropy loss of newly introduction of a water moleculeswas 7.8 kJ/mol.     

Skylight for Interior Lighting Design

It is inevitable for indoor lighting design to render a room lit by natural light, especially for an atelier or an indoor pool where there are many windows. This paper proposes a method for calculating the illuminance due to natural light, i.e. direct sunlight and skylight, passing through transparent planes such as window glass. The proposed method makes it possible to efficiently calculate such illuminance accurately, because it takes into account both non-uniform luminous intensity distribution of skylight and the distribution of transparency of glass according to incident angles of light. Several examples including the lighting design in an indoor pool, are shown to demonstrate the usefulness of the proposed method.     

A Novel Approach to Open “Dead Space” and Modify Interfacial Features of Carbon Nanotube Assemblies by a Microwave Shock

Despite 30-year development of carbon nanotube (CNT) based materials, harnessing the outstanding nanoscale properties of individual CNT for macroscale applications remains challenging. High specific surface area, a crucial feature of CNTs, often suffers from the formation of tightly packed bundles with inaccessible “dead space”. Herein, a novel “microwave shock” approach to open the “dead space” trapped within bundles is reported. Employing N₂ ambient during microwave irradiation, CNT bundles undergo an efficient structural alteration and interfacial modification simultaneously due to the strong radiative coupling, while the graphitic structure remains undamaged. In this way, a 15-fold increase (from 42 to 648 m² g⁻¹) in the interstitial surface area as well as the lithiophilic functionalization (≈1 atom% nitrogen doping) are achieved without the degradation of other properties. Furthermore, to highlight the merits of this microwave shock process, the treated CNT films are applied as a host material for the anode in a lithium metal battery and demonstrate the suppression of dendritic lithium growth and improve cycling stability. This microwave shock approach provides an efficient avenue to modify nanocarbon-based materials for further applications.     

Research and development of liquid hydrogen (LH2) temperature monitoring system for marine applications

Monitoring the temperature in liquid hydrogen (LH₂) storage tanks on ships is important for the safety of maritime navigation. In addition, accurate temperature measurement is also required for commercial transactions. Temperature and pressure define the density of liquid hydrogen, which is directly linked to trading interests. In this study, we developed and tested a liquid hydrogen temperature monitoring system that uses platinum resistance sensors with a nominal electrical resistance of approximately 1000 Ω at room temperature, PT-1000, for marine applications. The temperature measurements were carried out using a newly developed temperature monitoring system under different pressure conditions. The measured values are compared with a calibrated reference PT-1000 resistance thermometer. We confirm a measurement accuracy of ±50 mK in a pressure range of 0.1 MPa–0.5 MPa.     

A simple method for rendering penumbrae caused by sunlight

A simple rendering method for penumbrae caused by sunlight is proposed to create more realistic outdoor scenery. Only four points are used to define the penumbra area cast by a contour edge so that little storage is needed for penumbra areas. Complex penumbrae caused by such objects as curtains can be rendered. Calculation of illumination in the shadows cast by natural objects, such as trees, mapped on a transparent virtual plane is available. In order to show the usefulness of the proposed method, some computer-generated images with penumbrae are compared with those without penumbrae.     

Efficiency enhancement in a Cherenkov laser loaded with a Kerr-likemedium

Efficiency enhancement in energy conversion for a Cherenkov free elctron laser loaded with a Kerr-like medium is discussed with the aid of particle simulation. For the analysis of the problem, a two-dimensional model for the Cherenkov free electron laser is considered which is composed of a planar relativistic electron beam and a parallel plate waveguide one plate of which is loaded with a nonlinear dielectric sheet exhibiting a Kerr-like effect. To follow the growth of an electromagnetic wave and the decrease in the kinetic energy of the electron beam in the specified model of the Cherenkov free electron laser, a particular segment of the electron beam with the longitudinal length of one guide wavelength is picked out. In that segment, as it travels down the waveguide, the interaction between the electromagnetic wave and a group of electrons is analyzed with the use of the finite-difference time-domain (FDTD) method. The result of numerical simulation shows that the efficiency of energy transfer from the electron beam to the electromagnetic wave is greatly enhanced by the proper choice of the nonlinear parameter for a Kerr-like medium. The enhanced efficiency is due to the improved velocity matching between the electron beam and the electromagnetic wave, and to the self-focusing effect of a Kerr-like medium     

Analysis of irregular increase in sheet resistance of Ni silicides on transition from NiSi to NiSi2

The annealing conditions causing an irregular peak in sheet resistance of nickel silicides are investigated. It is found that the irregular rise in sheet resistance occurs at a critical temperature of 750-775 °C as a result of agglomeration related to phase transition from NiSi to NiSi₂. Experiments on the effect of temperature, heating rate and annealing duration in rapid thermal annealing revealed that the high-resistance state produced by annealing at the critical temperature could not be changed by subsequent annealing at higher temperature, and that the high-resistance state required 30-40 s at the critical temperature to form. Pre-annealing at 600 °C was found to suppress the later formation of the high-resistance state.     

A FATIGUE-CRACK-GROWTH-BASED ANALYSIS OF TWO-STEP CORROSION FATIGUE TESTS

Abstract A method for the analysis of two-step fatigue level sequences is proposed and compared with experimental results. Two-step loading tests of the aluminum alloy 2017-T4 in 3% sodium chloride solution have been carried out in conjunction with a replica technique used to monitor the growth of fatigue cracks. Fatigue cracks were nucleated at corrosion pits 10–15 μm in size, and crack growth rather than crack initiation was found to take up the major portion of the fatigue lifetime in these tests. The results could therefore be analyzed on the basis of the following constitutive relation for fatigue crack growth. da/dN=A(ΔK_eff-ΔK_effth)² This analysis was simplified since the influence of transients in the crack growth rate induced upon change in load level was found to be minimal. The approach provides a rational basis for dealing with load-sequence effects.