It has been important to understand interfacial phenomena of semiconductor/metal thin-films, like Fermi level pinning, and control them for highly reliable ULSI. GaAs is known as a valuable material used for high-frequency devices, high-efficient light-emitting devices, and so on. In order to understand and control interfacial phenomena on GaAs/metal contacts, electrical properties of GaAs/metal? thin-films (Au, Pt, Cu, Al) contacts by RF magnetron sputtering have been studied by measuring I-V and 1/C²-V properties before and after annealing. The results showed that the slope of barrier heights φ_B toward to metal work functions χ_m was about 0.1; hence, Schttoky model is probably unsuitable and Bardeen model may be well for GaAs, a covalent bond semiconductor. In cases of ohmic properties, the alloy of GaAs and metals formed by annealing and increased impurity concentration at interfaces may contribute for changing the electrical properties into ohmic ones.

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In order to improve wear resistance of white cast iron, cermet powder layer only and cermet powder layer mixed with some metallic powder were inserted by molten 27 mass% Cr white cast iron at 1773K. Various sizes of the cermet powder were adopted for the insertation. The microstructure of surface and vertical cross-section of the inserted layer was examined to investigate castability of the molten cast iron for these powder layer. The results obtained are as follows. (1) For the cermet powder size of more than 3.4mm, the inserted layer shows satisfactory metallographic structure. (2) For the cermet powder size of less than 3.4mm, many voids are located in the inserted layer and cermet powder remain, but good metallographic structure is obtaind by the addition of Ni powder or Cr powder. (3) For the mixed cermet powder added 50 vol.% Ni powder, a compression method to make a compact is available to obtain a good microstructure of inserted layer. (4) A suspension method for the cermet powder in the mold is also effective to obtain the good microstructure because it is easy to obtain a good admission of the molten cast iron into the cermet powder.

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A (111) surface of copper crystal was etched anodically under potentiostatic electrolysis in the electrolyte containing small amounts of NaBr and CuCl besides NaCl of high concentration. The vertical and lateral dissolution rates at dislocation sites and the vertical dissolution rate of matrix surface were examined by measuring the variations in depth and width of dislocation etch pits and dissolved depth of matrix surface with etching time, respectively. The effects of overpotential, temperature and inhibitor concentration on the dissolution rates are investigated and discussed. It is shown that the dissolution process at the dislocation site of copper crystal can be explained by the two-dimensioal nucleation theory for crystal dissolution.

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Construction sludge is the typical high water-content mud and is produced more than 10 million ton per year from the construction sites in Japan. However, the recycling rate of the construction sludge is extremely low. Therefore, we have already developed a new recycling system of high water-content mud by using the paper debris and polymer in order to increase the recycling rate of the construction sludge. By using this system, 200-500% water content mud has been modified to the landfill materials by 20 minutes mixing process. The modified mud has several features and one of the features of the modified mud is lightweight. The fields where lightweight landfill materials are effectively applied will be as follows:
1) The large scale reclaimed works:
2) A tree-planting on the rooftop to prevent heat island:
3) Measures works for landslides:
In this paper, a concept of producing the lightweight landfill materials from the construction sludge is described. In order to use the modified mud as the lightweight landfill materials, it is very important to know the density of the modified mud. Furthermore, the estimation of water content is also important to use the modified mud as vegetation soils. Therefore, theoretical considerations were carried out and the models to estimate the density and water content of modified mud by using above recycling system were developed. In order to examine the accuracy of the model, the specimen were made by using the imitation mud and actual construction sludge, and the density and water content of the modified mud were measured. It was confirmed that these models are almost reasonable by comparing the estimated values and actual ones of the modified mud. By using these models, the production of lightweight landfill materials which satisfy the necessary strength and density for the construction work will be possible by adjusting the water content of initial construction sludge.

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Pyrolyzed Japanese cedar (Cryptomeria japonica D. Don) bark was activated in a stream of CO₂ at 1123-1173K for 1h. Adsorption of N₂ at 77K and DRIFTS spectra were measured to investigate the porosity and surface properties of the activated materials. The resultant fibrous activated carbons showed the development of micro porosity which was characterized by large specific surface area greater than 1000m²g^-1, small external surface area of ca. 10m²g^-1, and total pore volume of 0.45-0.65mlg^-1. Pore size of the activated carbon distributed sharply around 0.3-0.4nm radius, indicating that micropores were selectively formed during activation reactions, while the amounts of meso- and macro-pores were negligibly small. Analysis of adsorption isotherms by α_s-plot method suggests that surface properties of the activated carbons from the cedar bark are different from those of ordinary carbon black. Peaks appeared in 900-1350cm^-1 region in the DRIFTS difference spectra between the activated carbon and the carbon black showed that principal functional groups on the surface of the cedar bark activated carbon were ether groups such as ether bridges between aromatic rings and cyclic ethers containing COCOC groups. It is indicated that the oxygenated functional groups produced on the surface of the activated carbons from the cedar bark may affect the surface characteristics of the activated ones.

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