Multilayer Debugging Process (A New Method of Screening)

In general, a small proportion of components will be substandard because of some imperfection in the control of the production process. Because no advance knowledge exists as to which are the substandard components, their presence affects the reliability. A great part of the substandard components can be eliminated by means of debugging procedures, but due to a nonzero proportion of defectives of the component population, it is impossible to eliminate all of the substandard components through conventional debugging processes. To remedy this drawback, this paper presents a new debugging process that is capable of eliminating almost all of the substandard components. From an analysis and comparison of the new debugging process with the conventional method, it has become evident that we can reduce the fraction defective of the lot after debugging by several orders of magnitude when compared with the conventional method.     

Electron beam damage of behenic acid films

The rate of fading of electron diffraction patterns of behenic acid monolayer crystals as well as multilayer crystals was measured at 100 kV at room temperature to investigate the dependence of beam damage on specimen thickness. The diffracted intensities for monolayers and double layers decreased nearly exponentially with electron exposure; however, the intensities for multilayers were unchanged during initial electron exposures, often increased temporarily and then decreased with electron exposure. The critical dose, D_e, defined as the dose at which the diffracted intensity falls to 1/e of its initial value, was 1.0 electrons/Ų for the monolayers, 1.8 electrons/Ų for the double layers and more for multilayers. These results lead to the conclusion that D_e for behenic acid increases nearly linearly with specimen thickness in the range of about 25–100 Å for dose rate of 0.1–2 electrons/Ų min.     

Growth of thick and low‐doped 4H‐SiC epitaxial layers in a vertical radiant‐heating VPE reactor

A new vertical radiant‐heating reactor has been designed and constructed for thick SiC vapor‐phase epitaxy (VPE). Growth of 4H‐SiC epitaxial layers is performed under a reduced pressure as low as 6.7 × 10³ Pa. A high growth rate exceeding 16 µm/h has been achieved in the reactor. Smooth surface is obtained by controlling the input C/Si ratio of source gases, and we have demonstrated growth of very thick layers over 160 µm with a mirrorlike morphology. Low‐background doping in the 10¹³ cm^?3 range (n‐type) and intentional n‐type doping in a range from low 10¹⁵ to low 10¹⁹ cm^?3 have also been demonstrated. We have performed photoluminescence spectroscopy and deep level transient spectroscopy to check impurities and intrinsic defects in the epitaxial layers, and the spectra show that the layers have a good purity and quality. © 2002 Scripta Technica, Electr Eng Jpn, 138(4): 18–25, 2002; DOI 10.1002/eej.1134     

A NEW HIGH ORDER SCHEME FOR CONVECTION EQUATION AND ITS APPLICATION

1. INTRODUCTIONThe choice of computational scheme for the convection term is the most difficult problem in numerical simulation of flow. Due to the development of modern numerical methods and practical needs for more efficient simulation, higher order sch…     

Shock Consolidation of Coarse Sic Powder

Sic compacts with 98.6% of theoretical density were obtained from coarse powder by a shock compaction technique. Microhardness values for the compacts obtained at 8 and 13 GPa ranged from 15.7 to 22.5 GPa and from 21.6 to 28.2 GPa, respectively. Scanning electron microscopy suggested that small amounts of molten material participated in the shock consolidation process.     

Low-threshold GaInNAs single-quantum-well lasers with emission wavelength over 1.3 /spl mu/m

Low-threshold GaInNAs single-quantum-well (SQW) lasers with emission wavelength over 1.3 mum are demonstrated. Epitaxial layers of the lasers are grown using an aluminium-free gas-source molecular-beam epitaxy (GS-MBE) to prevent any impurity or contamination related to aluminium that might be incorporated into the GaInNAs active layer. The fabricated laser is believed it exhibit the lowest threshold-current density (200 A/cm²) among GaInNAs-SQW lasers grown by MBE. Moreover, record low threshold current (5.2 mA) and long-wavelength (1.31 mum) emission were achieved in a ridge-waveguide laser at 25degC under continuous-wave operation     

Experimental study on in-vessel debris coolability in ALPHA program

In-vessel debris coolability experiments were performed in ALPHA program at JAERI. Aluminum oxide (Al₂O₃) produced by a thermite reaction was used as a debris simulant. Approximately 30 and 50 kg of Al₂O₃ were poured into a pool of nearly saturated water at the ambient pressure of approximately 1.3 MPa formed in a lower head experimental vessel. The post-test visual observation and measurement using an ultrasonic technique indicated the formation of a thin porous layer at the vicinity of the surface of the solidified Al₂O₃ and the interfacial gap between the solidified Al₂O₃ and the lower head experimental vessel wall. Thermal transient characteristics on the lower head experimental vessel wall observed in the experiments implied that the interfacial gap and the thin porous layer in the solidified Al₂O₃ layer acted as a thermal resistance during the initial heat-up stage, and water subsequently penetrated into the interfacial gap to effectively cool the lower head experimental vessel wall. The maximum heat flux removed from the experimental vessel was ranged from approximately 190 to 360 kW m⁻² while the temperature of the vessel wall decreased rapidly.     

Investigation of micro-structural transition through disproportionation and recombination during hydrogenation and dehydrogenation in Mg/Cu super-laminates

Micro/nano-structures and hydrogen storage properties of Mg/Cu super-laminates were investigated. Mg/Cu super-laminates showed reversible hydrogenation and dehydrogenation at 473 K. In order to clarify the process of hydrogenation and dehydrogenation at 473 K, we performed TEM observations of micro/nano-structures of the Mg/Cu super-laminates and Mg₂Cu powder prepared by conventional casting method. TEM observations revealed that the as-rolled Mg/Cu super-laminates had laminated structures in size of sub-micrometer thickness composed of Mg and Cu layers with dense lattice defects. The super-laminates after initial activation kept laminated structures and had uniformly distributed pores with a sub-micrometer diameter. On the other hand, the cast Mg₂Cu powder after initial activation had pores only beneath the surface oxide layers. It is considered that these micro/nano-structures of Mg/Cu super-laminates lead to lower dehydrogenation temperature and better kinetics, which would contribute to achieve high-performance hydrogen storage materials.     

Palladium‐Catalyzed Intermolecular Asymmetric Hydroamination with 4,4′‐Disubstituted BINAP and SEGPHOS

A family of tunable precatalysts [Pd((S)‐L*)(NCMe)₂](OTf)₂, where L* is 4,4′‐disubstituted BINAP or SEGPHOS, was synthesized and used for the asymmetric intermolecular hydroamination of aniline to vinylarenes with ee values of up to 85 %, and it is believed that the bulky groups on the 4,4′‐positions and the narrower dihedral angle of the biaryl moiety are responsible for the ee enhancement in these reactions.