Characterization of hydrogenated amorphous silicon-carbon films deposited by hybrid-plasma CVD

We propose a new deposition process, hybrid-plasma CVD, to overcome the difference in decomposition of source gases. In this new process, SiH₄ are CH₄are decomposed individually in a RF plasma and a microwave plasma, respectively, for the deposition of CH₄ hydrogenated amorphous silicon-carbon. Effectent decomposition of CH₄ by a microwave plasma reduces the excess hydrogenation of carbon atoms. Reactions in the hybrid-plasma CVD are investigated by quadruple mass spectroscopy. Film structures are investigated by Fourier transform infrared absopption and X-ray photoelectron spectroscopy, and electrical properties are also examined. The films show low hydrogenation of the C atom compared to the films of glow discharge method. Moreover, the films with optical bandgap less than 2.2 eV show photoconductivesies in the range of 10⁻⁵ S/cm.     

A somatic cell hybrid map of human chromosome 13

We have constructed a chromosome 13 somatic cell hybrid map using seven cell lines: PGMEA6, a hybrid containing the entire chromosome 13, and six hybrids containing various deletions of chromosome 13 (BARF7, PPF22, KBF11, KSF39, CF25, and CF27). We have mapped 80 markers that define 10 regions of chromosome 13 with respect to 10 breakpoints in the mapping panel; these regions range in size from 4 to 24 Mb, with an average size of 8 Mb. The 80 markers sublocalized on our mapping panel include 10 Alu-PCR clones, 6 of which were converted to sequence-tagged sites; 40 (CA)n repeat-containing clones, 27 of which are microsatellite PCR markers; 8 (AAAG)n repeat-containing PCR markers, 1 two-allele PCR marker, 4 genes or expressed sequences, and 17 anonymous DNA probes. This low-resolution physical map can be used as a backbone map for more refined physical mapping using radiation hybrids or yeast artificial chromosomes.     

Dechanneling by lattice defects

Backscattering measurements were used to study the dechanneling of ¹H⁺ and ⁴He⁺ ions in irradiated crystals of Al and Cu. The effect of the annealing of self-interstitials and vacancies on dechanneling was correlated with the formation of Al-Ag mixed dumbbells and vacancy-Sn atom complexes in dilute alloys of Al. The depth profile of damage produced in Al-0.1 at.% Ag by 0.5 MeV He⁺ irradiation was measured by ¹H⁺ dechanneling. The rate of dechanneling of ¹H⁺ ions in ⁴H⁺-irradiated Al-0.1 at.% Ag Cu-0.06 at.% Au and Cu-0.25 at.% Be crystals exhibited ion energy dependences between E^?0.5 and E^?0.9. Dechanneling from small defect clusters in Cu-0.06 at.% Au increased linearly with increasing sample temperature. The dechanneling cross-sections for Al-Ag mixed dumbbells in Al, and Cu-Be mixed dumbbells in Cu were σ_d～- 8 × 10^?18 cm². The results were compared with dechanneling theories.     

High performance of high-voltage 4H-SiC Schottky barrier diodes

High performance of high-voltage rectifiers could be realized utilizing 4H-SiC Schottky barrier diodes. A typical specific on-resistance (R_on) of these devices was 1.4×10³ Ω cm³ at 24°C (room temperature) with breakdown voltages as high as 800 V. These devices based on 4H-SiC had R _on's lower than 6H-SiC based high-power rectifiers with the same breakdown voltage. As for Schottky contact metals, Au, Ni, and Ti were employed in this study. The barrier heights of these metals for 4H-SiC were determined by the analysis of current-voltage characteristics, and the reduction of power loss could be achieved by controlling the barrier heights     

A multi-exciton model for the electronic sputtering of oxides

Three models are examined for the electronic sputtering by high energy heavy ions. It is found that the charged fraction of the sputtered particles is small (less than 10% in this study) and hence, Coulomb explosion model is unsound. According to the thermal spike model, rapid thermal quenching of the melted zone is anticipated, implying amorphisation of SiO₂ single crystal (c-SiO₂). X-ray diffraction results indicate no amorphisation of c-SiO₂, suggesting no melting. Moreover, the electronic sputtering yields of both c-SiO₂ and amorphous-SiO₂ (a-SiO₂) have been found to be the same. With these results and thermal properties of both c-SiO₂ and a-SiO₂, thermal spike model is examined further and appears to be unfavorable. A multi-exciton model is suggested for the electronic sputtering.     

Factors affecting the characteristics of the negative electrodes for nickel-hydrogen batteries

The multicomponent hydrogen storage alloy with composition MMNi_3.31Mn_0.37A1_0.28Co_0.64 was used as a negative electrode material. After packing the alloy particles in a porous nickel substrate, press forming was carried out to bond them. The effects of particle size and forming pressure on electrode performance were examined in 6 m KOH solution. The electrochemical properties of the negative electrode, such as discharge capacity and high-rate dischargeability, were remarkably improved by increasing the alloy particle size and forming pressure.     

Introducing the FR500 embedded microprocessor

Because conventional RISC processors have insufficient processing power to support the continuing development of digital consumer products, we need a new high performance processor for multimedia applications. Processing multimedia video images requires more than 10 times the currently available performance. At Fujitsu, we provide this higher performance in software to attain a high degree of flexibility. We developed the FR500 microprocessor with a novel embedded VLIW (very long instruction word) architecture for use in such digital consumer products. The FR500 is the first product in the FR-V line, Fujitsu's generic name for VLIW architecture microprocessors. The FR-V line offers the flexibility to develop new products optimized for a wide variety of digital consumer products. In this paper, we describe the FR-V architecture, which includes our variable-length VLIW and instruction set architectures, speculative execution control, and conditional execution control. We also evaluate its performance     

Formation of novel sintered composites by high-pressure crystallization of amorphous ceramics

A combination of chemical vapour deposition (CVD) and high-pressure (HP) techniques has achieved the fabrication of the zincblende form of boron nitride (z-BN)-based ceramic composites. The CVD technique provides amorphous B-N-X (X = aluminium, silicon or titanium). The HP technique renders the amorphous samples crystalline and decomposition into z-BN plus the respective nitride (-Si₃N₄ for instance) occurs. Compacts of the composites are obtained byin situ sintering under high pressure. The compacts exhibit peculiar microstructures composed of z-BN nano-crystals homogeneously dispersed in the nitride matrices.     

Effects of wet oxidation/anneal on interface properties ofthermally oxidized SiO2/SiC MOS system and MOSFET's

Effects of wet atmosphere during oxidation and anneal on thermally oxidized p-type and n-type MOS interface properties were systematically investigated for both 4H- and 6H-SiC. Deep interface states and fixed oxide charges were mainly discussed. The wet atmosphere was effective to reduce a negative flatband shift caused by deep donor-type interface states in p-type SiC MOS capacitors. Negative fixed charges, however, appeared near the interface during wet reoxidation anneal. In n-type SIC MOS capacitors, the flatband shift indicated a positive value when using wet atmosphere. The relation between interface properties and characteristics of n-channel planar 6H-SiC metal-oxide-semiconductor field effect transistors (MOSFETs) was also investigated. There was little relation between the interface properties of p-type MOS capacitors and the channel mobility of MOSFETs. The threshold voltage of MOSFETs processed by wet reoxidation anneal was higher than that of without reoxidation anneal. A clear relation between the threshold voltage and the channel mobility was observed in MOSFETs fabricated on the same substrate     

Crowned polyacetylene. 4. Solid state NMR studies on molecular motions and cis-trans isomerization of poly(4'-ethynylbenzo-15-crown-5)

Summary Chain conformations and molecular motions of poly(4'-ethynylbenzo-15-crown-5) (PEB15C5) and its annealed sample (AN-PEB15C5) in the solid state were investigated by ¹H NMR and CP-MAS ¹³C NMR measurements. The chain conformation was determined to be cis-transoidal for PEB15C5 and 70°-deflected trans-transoidal for AN-PEB15C5. The exothermic peak at 180°C observed in the DSC thermogram was due to the cis-trans isomerization. Motional modes of each chain were observed in the three temperature regions of γ, β and α with an increase of temperature, which are attributed to the sterically hindered oscillation of the side chains and the vibrational and free rotations of the main chain with the oscillating side chain. The free rotation of the trans chain in the α-region occured in a lower temperature region by 15°C, comparing with that of cis chain. Received: 1 December 1997/Revised version: 5 January 1998/Accepted: 12 January 1998