Deep submicrometer super self-aligned Si bipolar technology with25.4 ps ECL

A new deep submicron double-poly self-aligned Si bipolar technology has been developed using a 0.3-μm design rule, a collector polysilicon trench electrode, and oxide-filled trench isolation. This technology is called “High-Performance Super Self-Aligned Process Technology” or HSST. 0.3-μm minimum patterning is achieved by electron-beam direct writing technology. The HSST bipolar transistor is 2.5 times smaller than the previous 1-μm SST-1B. Owing to its horizontal reduction and an f_T of 22.3 GHz at V_ce=1 V, the ECL gate attains 25.4 ps/G at 1.58 mA, which is a 30% improvement on the SST-1B. By including parasitic capacitances of the base polyelectrode and polyresistors, the ECL delay time is accurately simulated for low-power operation. It is shown that the HSST is a very promising technology for the development of future high-speed communication systems     

Oxygen potentials of (th, u)o2+x solid solutions

The oxygen potential and the nonstoichiometry ($\text{x}$) for (Th_1?yU_y)O_2+x were measured in situ at 1000° 1&;#x0303;200°C using a solid electrolyte oxygen sensor and a thermobalance, respectively. The results showed that the oxygen potentials of (Th_1?yU_y)O_2+x are not a function only of the U valence in the investigated range of $\text{0.05?y?0.20}$. The oxygen potentials at 1200°C decrease negatively with increasing thorium content at a given U valence. The calculated activity coefficients of urania in the solutions indicate an increasing positive deviation from ideality with increasing U valence.     

The U0.8Pu0.2C-W system

A phase diagram of the U_0.8Pu_0.2C-W system has been established based on X-ray diffraction measurements and metallographic observations. A peritectic four-phase reaction has been found to occur at 2100 ± 40°C:

The peritectic point is close to U_0.8Pu_0.2C-27 wt.%W. Composition of the peritectic liquid is near 48(U + Pu)/18W/34C (at %) by analogy with the UC-W system. The liquid phase transforms, during rapid cooling, to a metastable mixture [(U, Pu)C + (U, Pu)metal + W] with accompanied retention of (U, Pu)WC_1.75. The (U, Pu)WC_1.75 phase crystallizes in a UWC_1.75-type monoclinic structure. Essentially single-phase (U_0.8Pu_0.2)WC_1.75 has been produced by sufficient annealing of the arc-melted specimen, with lattice parameters: a₀ = 5.6257 ± 0.0008 Å, b₀= 3.2498 ± 0.0005Å, c₀ = 11.623 ± 0.002 Å, β = 109.61 ± 0.01°. This compound perhaps melts incongruently as:

The terminal solid solubility limit of tungsten in U_0.8Pu_0.2C increases from about 0.8 wt%W at 1500°C to a maximum of about 3.2 wt%W at 2100°C. The partial molar heat of solution of tungsten in U_0.8Pu_0.2C is approximately 14.4 kcal/mole. Un diagramme de phase du système U_0,8Pu_0,2C-W a étée'tabli en se basant sur les mesures par diffraction aux rayons X et par examen métallographique. Une réaction péritectique a quatre phases a été observée à 2100 ± 40°C:

     

Inverse base-width modulation and collector space-charge-regionwidening: degrading effects at high current densities in highly scaledBJT's (and HBT's)

Degrading effects on BJT speed performance due to current-induced perturbation of the collector-base junction space-charge region (SCR) prior to base pushout are analyzed and assessed. Inverse base-width modulation (IBWM)-a widening of the quasi-neutral base width-and collector SCR-width widening (SCRW) in highly scaled BJT's and HBT's are identified as important mechanisms governing device speed degradation at high currents. IBWM, which increases the base transit time, is described analytically to distinguish it from base pushout, or quasi-saturation. MMSPICE simulations of an aggressive SiGe-base HBT technology, supported by measured data, show that the speed (f_T) degradation associated with IBWM is significant at currents well below the onset of base pushout, which underlies the speed degradation of lesser scaled BJT's. Simulations of further scaled devices show that SCRW can be the predominant mechanism of speed degradation at high current densities     

Contribution to the study of the UCsMoIO system

The reaction in the UCsMoIO system at 1073 K have been studied as a function of oxygen potential. The chemical constitution and the morphology of the phases formed were examined by electron-probe microanalyzer and X-ray diffractometer. The existence of a two-phase field UO_2+x + Cs₂UO₄ was confirmed in the UCsO system. The threshold oxygen potential was determined for the decomposition of CsI by UO_2+x to form Cs₂U₄O₁₂ and gaseous iodine. The effect of molybdenum on the UO_2+x−CsI reaction was also investigated. Predominance of Cs₂MoO₄ over Cs₂UO₄ was verified in a certain range of oxygen potentials. Some assessments and interpertations of the experimental results were made with the aid of thermodynamic calculations.     

Development of quality of life questionnaire for patients with colorectal cancer in surgical area--a study of reliability and validity of Tokyo Yamabuki Forum Version

We developed a new questionnaire in the surgical area based on a core quality of life (QOL) questionnaire for patients with gastrointestinal cancer. In this study, we investigated the validity and reliability of a QOL questionnaire (Tokyo Yamabuki Forum Version) for patients with colorectal cancer. The questionnaire was composed of 17 items including 5 scales (basic sensory scale, psychological scale, physiological scale, defection-related scale and active scale) and a face scale as an global scale. The time needed to answer questionnaires was expected to be around 7 minutes and the questionnaires should basically be answered by the patients themselves everyday in the hospital. The study was performed in 10 hospitals in the Tokyo area, and 394 samples collected from 21 patients with rectal and colonic cancers were analyzed. A number of respondents failed to answer the question "Do you feel your foods tasty?", so we judged this item inappropriate and deleted it from the analysis. Fifteen items, including 5 scales showed satisfactory internal consistency and construct validity in correlation and factor analyses. Performance status showed a low correlation between each item, each scale and the global scale, while SDS and STAI showed an inordinately negative correlation with the fundamental and physical scales. Especially, SDS revealed an extremely close correlation with the active scale, and STAI showed an excessive correlation with the psychological scale. In the time course of QOL under chemotherapy, reductions (aggravations) were observed in both the total score of 15 items and global scale within one week postoperatively, but after that recovered to preoperative levels at 2 weeks postoperatively. A tendency to QOL improvement was observed 2 weeks after starting chemotherapy or chemoimmunotherapy. QOL of 13 patients was measured over 3 months, and the longest term was 8 months. The results suggested that this QOL questionnaire has sufficient reliability and validity to be usable for patients with colorectal cancer in the surgical area and that this model is applicable for long-term QOL surveys and frequent measurement.     

Fission xenon release from lightly irradiated (Th,U)O2 powders

The release of ¹³³Xe from (Th,U)O₂ was studied at a low fission density by using a post-irradiation technique. The uranium concentrations of the specimens ranged from 0.15 to 20 mol% U0₂. Heating curves of the release gave almost the same pattern in shape, while the total release, which was the combination of an in-pile release and a post-irradiation release up to 1000°C, increased with uranium concentration except for the nominally pure ThO₂. Effects of preparation conditions of specimens such as atmosphere, temperature and stoichiometry were also studied and found to be minor. Possible release mechanisms were discussed.