Structural advantages of rectangular-like channel cross-section on electrical characteristics of silicon nanowire field-effect transistors

We have experimentally demonstrated structural advantages due to rounded corners of rectangular-like cross-section of silicon nanowire (SiNW) field-effect transistors (FETs) on on-current (I_ON), inversion charge density normalized by a peripheral length of channel cross-section (Q_inv) and effective carrier mobility (μ_eff). The I_ON was evaluated at the overdrive voltage (V_OV) of 1.0 V, which is the difference between gate voltage (V_g) and the threshold voltage (V_th), and at the drain voltage of 1.0 V. The SiNW nFETs have revealed high I_ON of 1600 μA/μm of the channel width (w_NW) of 19 nm and height (h_NW) of 12 nm with the gate length (L_g) of 65 nm. We have separated the amount of on-current per wire at V_OV = 1.0 V to a corner component and a flat surface component, and the contribution of the corners was nearly 60% of the total I_ON of the SiNW nFET with L_g of 65 nm. Higher Q_inv at V_OV = 1.0 V evaluated by advanced split-CV method was obtained with narrower SiNW FET, and it has been revealed the amount of inversion charge near corners occupied 50% of all the amount of inversion charge of the SiNW FET (w_NW = 19 nm and h_NW = 12 nm). We also obtained high μ_eff of the SiNW FETs compared with that of SOI planar nFETs. The μ_eff at the corners of SiNW FET has been calculated with the separated amount of inversion charge and drain conductance. Higher μ_eff around corners is obtained than the original μ_eff of the SiNW nFETs. The higher μ_eff and the large fractions of I_ON and Q_inv around the corners indicate that the rounded corners of rectangular-like cross-sections play important roles on the enhancement of the electrical performance of the SiNW nFETs.     

Estimation of mechanochemical dechlorination rate of poly(vinyl chlorde)

Poly(vinyl chloride) (PVC) was ground in air with CaO in the presence of quartz powder as a grinding aid by a small-scale planetary ball mill to investigate the relation of the dechlorination rate of PVC with the impact energy of the balls calculated from a computer simulation based on the Discrete Element Method under various conditions. Mechanochemical dechlorination proceeds as the grinding progresses and is improved with an increase in both the mill speed and the amount of balls introduced into the mill. The same trend can be seen in the relation between the specific normal impact energy of the balls and the rotational speed. The relationship between the observed dechlorination rate and the computed normal impact energy of the balls is linear, with a correlation coefficient of 0.965. This relationship can be used to estimate the dechlorination rate of PVC in a large-scale planetary ball mill.     

Identification of Aloe species by random amplified polymorphic DNA (RAPD) analysis

Juice and integument of leaves of 3 Aloe species, Aloe vera, A. ferox and A. africana, are not allowed to be used as food according to the Pharmaceutical Affairs Law in Japan. On the other hand, whole leaves of A. arborescens can be used as food. The present study was designed to distinguish Aloe species by random amplified polymorphic DNA (RAPD) analysis. DNA was isolated from fresh and dried leaves of the 4 Aloe species. Five out of 32 different 10-mer primers examined were useful for analysis. By comparison of the characteristic bands of PCR products on agarose gel, it was possible to distinguish the 4 species. Thus, the botanical species of Aloe in commercial food products can be identified by RAPD analysis.     

Fermentation Process and Grain Structure of Baked Breads from Frozen Dough Using Freeze-Tolerant Yeasts

The fermentation process for frozen doughs using freeze‐sensitive (Saccharomyces cerevisiae, Kyowa for sweet bread; S. cerevisiae, FC for white bread) and freeze‐tolerant (S. cerevisiae, YF for sweet bread) yeasts was traced by magnetic resonance imaging (MRI). Grain network structures of baked breads were also visualized by MRI. Prefermentation before freezing, punching and remolding, or resheeting and molding treatments increased loaf volume by 10 to 110% for the baked breads using freeze‐tolerant yeast, while these treatments decreased loaf volume by 70% using freeze‐sensitive yeast. The first fermentation before freezing and the second fermentation with punching or resheeting after thawing are useful for obtaining good quality breads from frozen dough using freeze‐tolerant yeast.     

A new modeling approach for circuit‐field‐coupled time‐stepping electromagnetic analysis of saturated interior permanent magnet synchronous motors

This paper proposes a new modeling approach for circuit‐field‐coupled time‐stepping electromagnetic analysis of a saturated interior permanent magnet synchronous motor (IPMSM). To predict the drive performance quickly, the proposed approach consists of a dynamic simulator based on a new analytical model of the d‐ and q‐axis magnetization characteristics (λ‐i_d‐i_q‐θ). The model can take into account not only cross‐saturation but also the harmonics of the inductance distributions and EMF waveforms. The validity of the model is verified from suitable simulation results for the instantaneous current and torque waveforms of the IPMSM. The proposed analysis leads to a dramatic reduction in the computation time compared to circuit‐field‐coupled time‐stepping FEA, while maintaining analytical accuracy. The effectiveness of the proposed method is experimentally verified using a 10‐kW, 15,000‐rpm concentrated‐winding IPM motor. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 174(1): 49–58, 2011; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21024     

Depth Profiling of Hydrogen and Oxygen in Ferroelectric Films Using High-Energy Ion Beam

A characterization technique for oxide ferroelectric materials using high-energy ion beam is presented. In this study, depth profiles of chemical elements are obtained for SBT films grown by MOD method and by MOCVD method respectively. Hydrogen depth profiles are taken by ERD technique with an Al absorber foil. Depth profiles of other elements are determined with RBS technique. For the MOD-grown sample, the elemental amount ratio was determined as Sr1.00Bi2.06 ± 0.03Ta2.02 ± 0.03O8.33 ± 0.17. The oxygen deficiency in the MOD-grown SBT film was uniformly observed at every depths. For the MOCVD-sample and the MOD-sample, the underlying Pt electrode layers contained 4.7 at.% and 3.8 at.% of hydrogen respectively.     

Countable limit sets of unimodal maps

We show that for any positive integer n, there exists a unimodal map whose turning point has a countable ω-limit set of depth n. We also show that the quadratic map F(x) = 1 − 2x ² admits countable ω-limit sets of depth n for all positive integer n.     

Ideal-Gas Heat Capacity for 2,3,3,3-Tetrafluoropropene (HFO-1234yf) Determined from Speed-of-Sound Measurements

The isobaric ideal-gas heat capacity for HFO-1234yf, which is expected to be one of the best alternative refrigerants for HFC-134a, was determined on the basis of speed-of-sound measurements in the gaseous phase. The speed of sound was measured by means of the acoustic resonance method using a spherical cavity. The resonance frequency in the spherical cavity containing the sample gas was measured to determine the speed of sound. After correcting for some effects such as the thermal boundary layer and deformation of the cavity on the resonance frequency, the speed of sound was obtained with a relative uncertainty of 0.01 %. Using the measured speed-of-sound data, the acoustic-virial equation was formulated and the isobaric ideal-gas heat capacity was determined with a relative uncertainty of 0.1 %. A temperature correlation function of the isobaric ideal-gas heat capacity for HFO-1234yf was also developed.     

Effect of surface roughness on elastohydrodynamic traction: Part 1

The effect of surface roughness on traction performance was experimentally studied using a two‐roller tester. The nature of the contact was investigated using electrical resistance and electrical capacitance methods. Increased shear stress was observed in the viscous region, which could be attributed to a higher average shear rate and to greater viscosity under EHD contact conditions due to pressure fluctuations caused by the surface texture.