Nagayasu Ikeda

Characteristics of Impurity-Doped GaSe Radiation Detectors

The properties of GaSe radiation detectors doped with Si, Ge and Sn were investigated. It was found that doping with these impurities substantially decreased the leakage current and that most detectors doped with the impurities at about 0.005 to 0.1 at.% showed fairly good energy resolutions from 4 to 15% for 241Am 5.5 MeV alpha particles, while most pure GaSe detectors did not function because of their excessively large leakage current.

Dependence of saturation magnetization and coercivity of Co‐Cr/Al multilayered films on Co‐Cr layer thickness

Co81Cr19/Al multilayered films with thicknesses of Co81Cr19 layers in the range of 46–170 A and Al ones of 7 A have been prepared on glass‐slide substrate at room temperature by using the facing targets sputtering (FTS) apparatus. The dependence of the magnetic and crystallographic characteristics on the thickness of Co‐Cr layers have been investigated. The magnetoresistance effect of the specimen films have been also examined. The intrinsic Co81Cr19 layers were composed of hcp phase crystallites with well orientation of the c axis normal to the film plane. Both the crystallinity of Co81Cr19 layers was improved and the d spacing between the c planes was expanded by using the Al interlayers as ultrathin as 7 A. The easy direction of magnetization in the films was perpendicular to the film plane. The saturation magnetization, the coercivity, the in‐plane squareness ratio and the anisotropy field depended strongly on the thickness of Co81Cr19 layer. On the other hand, the magnetoresistivity ratio was negativ...

Annealing dependence of coercivity, anisotropy field, and resistivity for amorphous CoZrNb films deposited by dc planar magnetron sputtering

Amorphous CoZrNb films have been deposited by magnetron sputtering which can greatly improve the utilization efficiency of a magnetic alloy target with high permeability. The saturation magnetization 4πMs of the CoZrNb films was about 14 kG. The easy and hard axes of magnetization of the films were orthogonal to each other in the film plane. The coercivity Hc in the easy and hard directions decreased from 0.9 to 0.2 Oe after annealing in a rotating dc magnetic field HA. However, Hc increased drastically to 20 Oe by heating at the annealing temperature TA of 400 °C. With increasing TA and HA, the anisotropy field Hk gradually decreased from 12 to 1 Oe and the resistivity ρ also decreased from 200 to 150 μΩ cm. Consequently, it was found that Hc and ρ depended strongly on TA; and that Hk had definite relationships with both TA and HA.

Investigation of composition uniformity of MoSix sputtering films based on measurement of angular distribution of sputtered atoms

Abstract The angular distribution of Mo atoms and that of Si atoms ejected from an MoSi 2.5 sintered target in d.c. magnetron sputtering, were measured and it was found that Si atoms were more apt to be ejected normally than Mo atoms. The composition distribution of the MoSi x film calculated using the angular distributions nearly agreed with the measured one; thus, it was clearly demonstrated that the difference between the angular distribution of Mo atoms and that of Si atoms causes the non-uniformity of the MoSi x film. The dependence of the composition distribution on the discharge voltage was also investigated and it was shown that the composition distribution becomes more uniform by increasing the discharge voltage.

A comparative study of CoZrNb and NiFe targets in discharge and sputtering using plasma confining type of magnetron sputtering method

CoZrNb and NiFe films have been deposited by a plasma-confining type magnetron sputtering method which can greatly improve the utilization efficiency of a magnetic alloy target with high permeability and completely suppress the bombardment of the substrate by high-energy gamma -electrons. Applying an auxiliary solenoid magnetic field H/sub E/ perpendicular to the target plane improved the target utilization efficiencies in volume for CoZrNb and NiFe targets from 32 to 51% and from 25 to 41%, respectively. In both targets, the maximum deposition rates were above 0.2 mu m/min. All CoZrNb films deposited by this method were composed of FCC-phase crystallites with the NiFe

Improvement of toroidal plasma (TP) type sputtering for depositing Co-Cr films on plasma-free substrates

Co-Cr films for perpendicular recording have been deposited by toroidal plasma (TP) sputtering method. A magnetic field was applied by a solenoid coil or a magnet was attached to the outer pole to change the plasma state during sputtering. When the magnetic field was applied using the solenoid coil, the discharge current, film thickness and film composition, saturation magnetization of 480 approximately 800 emu/cm/sup 3/, and coercivity of 250 approximately 350 Oe in the films depended on the plasma state. On the other hand, by attaching the magnet to the outer pole, the magnetic flux distribution in front of the target plane was significantly improved. Therefore, the applied voltage to the electrodes was reduced from 520 to 440 V at an Ar gas pressure of 0.2 Pa. The erosion profile of the targets was changed, and variations in the film thickness and the Co content over the whole film plane were reduced. >

Uniformity of sputtered films formed by fan-shaped composite targets

Abstract The target composed of fan-shaped metal plates, which the present authors call the fan-shaped composite target, is one of the most practical targets. However, the optimization of its configuration, that is the selection of the number of fans in a target, has never been discussed. While the number of fans in a target should be large with respect to the film uniformity, it should be small with respect to the cost of target production. In this study, the uniformity of the thickness and the composition of the films formed by Al-Cu fan-shaped composite targets with various numbers of fans was investigated. The data were analysed using a model for the calculation of the thickness and the composition. It was found that the number should be more than rougly 16, assuming that the upper limit of the uniformity was, for example, 5% for both the thickness and the composition.

Classification of ground faults in distribution lines according to phase-plane trajectories of waveforms

Recently, a greater demand for stable supply of electric power has resulted from a higher standard of living. It becomes important that the causes and locations of ground faults in distribution lines be found early and defects be repaired as soon as possible. Therefore, a unit for recording the waveform I0 of ground faults current and the waveform V0 of its voltage is installed in distribution substations. The establishment of a technology to distinguish fault causes automatically is being hastened. This paper presents a new classification method for ground fault waveforms, based on phase-plane trajectories for the current or voltage and their differential values. Examinations of ground fault waveforms based on real data show that the waveform of current I0 is more suitable than that of voltage V0 for the classification of waveforms at ground faults and that the trajectory of each of the three types of waveforms, such as sine waves, trapezoidal waves, and spikes, has all of the characteristics in its figure. It is also found from the distribution of 167 sampling points on the phase plane that any waveforms at a real ground fault may be classified into three characteristic point distributions, which gives the possibility of easy display for the classification of ground fault causes.

Step-Coverage Simulation for Molybdenum Silicide Sputtering Film

Step-coverage calculation for molybdenum silicide films was carried out using a model constructed by modifying the string model often used for the calculation of aluminum film step coverage. In the model, the film composition around steps as well as the thickness can be calculated. It was concluded that the difference between the angular distribution of the Mo atom and that of the Si atom caused not only the nonuniformity of the film composition at flat surface but also the deviation of the film composition around steps from that at flat surface.