Hiroji Mitsuhashi

Bio: Hiroji Mitsuhashi is an academic researcher from Shizuoka University. The author has contributed to research in topics: Electrical resistivity and conductivity & Quenching (fluorescence). The author has an hindex of 7, co-authored 20 publications receiving 253 citations.

Structure and Electrical Properties of Titanium Nitride Films

Abstract: Metallic titanium, in nitrogen atmosphere with specified pressures (pN) ranging from 10-6 to 10-4 Torr, was evaporated on glass substrates heated at temperatures (Ts) between 300 to 500°C. X-ray analysis revealed that the films were composed of α-titanium, distorted titanium phase, amorphous phase, and TiN. The distorted titanium phase was found to extend to a high concentration of nitrogen (x=0.5). In particular, the specimens evaporated at pN=2.0×10-5 Torr and Ts=500°C had maximum resistivity of 270 µΩ-cm and a very small negative value of the temperature coefficient of resistance (0 to -20 ppm/°C) for an extended range of temperatures (-190 to 200°C). The excess resistivity of the distorted titanium phase can be mainly interpreted in terms of two kinds of carrier scattering, one due to nitrogen atoms randomly distributed at vacant interstitials, another attributable to grain boundaries involved.

X-Ray Diffraction Data on Evaporated Organic Films of Fatty Acids

Abstract: It was found by X-ray analysis and mass-spectrography that organic films of margaric and palmitic acids, belonging to a group of long chain saturated fatty acids, were obtained by thermal evaporation in vacuum. The present paper deals with their structural analysis by the powder diffraction X-ray technique: They are characterised by the fact that they posess a preferred orientation of the monoclinic structure with the basal plane which is parallel to the substrate plane, and that they show no thermal decomposition of the powders. In addition, the X-ray diffraction data on powder margaric acid is presented which exhibit several more peaks, not reported in an earlier work. The Miller indices are also assigned to the initial several peaks in the case of margaric acid. Alternation in physical properties expected between odd and even members of the fatty acids could not be found between margaric and palmitic acids as far as the crystal structure of the films is concerned.

Mechanical properties of thin films

Abstract: The mechanical properties of thin films on substrates are described and studied. It is shown that very large stresses may be present in the thin films that comprise integrated circuits and magnetic disks and that these stresses can cause deformation and fracture to occur. It is argued that the approaches that have proven useful in the study of bulk structural materials can be used to understand the mechanical behavior of thin film materials. Understanding the mechanical properties of thin films on substrates requires an understanding of the stresses in thin film structures as well as a knowledge of the mechanisms by which thin films deform. The fundamentals of these processes are reviewed. For a crystalline film on a nondeformable substrate, a key problem involves the movement of dislocations in the film. An analysis of this problem provides insight into both the formation of misfit dislocations in epitaxial thin films and the high strengths of thin metal films on substrates. It is demonstrated that the kinetics of dislocation motion at high temperatures are expecially important to the understanding of the formation of misfit dislocations in heteroepitaxial structures. The experimental study of mechanical properties of thin films requires the development and use of nontraditional mechanical testing techniques. Some of the techniques that have been developed recently are described. The measurement of substrate curvature by laser scanning is shown to be an effective way of measuring the biaxial stresses in thin films and studying the biaxial deformation properties at elevated temperatures. Submicron indentation testing techniques, which make use of the Nanoindenter, are also reviewed. The mechanical properties that can be studied using this instrument are described, including hardness, elastic modulus, and time-dependent deformation properties. Finally, a new testing technique involving the deflection of microbeam samples of thin film materials made by integrated circuit manufacturing methods is described. It is shown that both elastic and plastic properties of thin film materials can be measured using this technique.