Shin-ichi Aoqui

B-concentration dependence on anisotropy field of CoFeB thin film for gigahertz frequency use

B was added to the high moment CoFe thin films (Co/sub 35/Fe/sub 65/, Co/sub 25/Fe/sub 75/, and Co/sub 15/Fe/sub 85/) using synchronous triple-RF magnetron sputtering to obtain the films with large anisotropy fields greater than 500 Oe. These films required inductor core materials operating at the frequencies of several gigahertz. Magnetic properties and the crystalline structure of the CoFeB films were investigated. It was found that the B addition increased the anisotropy field to 400-700 Oe and that the increase in anisotropy field was associated with changes in the crystalline structure, crystallite sizes, and crystallite orientation. The results indicated that CoFeB films have potential for use in magnetic cores and inductors operating at gigahertz frequencies.

Experimental and numerical study on pulsed-laser annealing process of diamond-like carbon thin films

Abstract The diamond-like carbon (DLC) films were deposited by KrF excimer laser (λ=248 nm) ablation under H 2 atmosphere of 200 mtorr with 6 J/cm 2 . The prepared DLC thin film was mounted on the holder and the film surface was irradiated with the third harmonic of a single pulsed of Nd:YAG laser (λ=355 nm) or a pulsed KrF excimer laser. The experiments were performed in air and the substrate was held at room temperature. The threshold energy density for surface damage is measured by inspecting the surface after a single laser shot of increasing fluence to observe the onset of surface damage. The damage threshold energy density for DLC film flashed by a pulsed Nd:YAG laser is in the range 60–80 mJ/cm 2 . The dynamics of pulsed nanosecond laser heating process is simulated by the solution of the one-dimensional heat conduction equation. The finite element method (FEM) is applied to solve the equation. At the laser fluence of 80 mJ/cm 2 with the Nd:YAG laser, the surface reaches the maximum temperature of 785°C at 48 ns. The experimental and calculated results show that the damage temperature of DLC film is smaller than the vaporization temperature of solid carbon. Moreover, the transmission spectra of DLC films before and after irradiation were measured. The graphitization occurred on the sample after irradiation over threshold energy for surface damage.

Pulsed laser deposition of carbon nitride thin films from graphite targets

Abstract Carbon nitride thin films were synthesized on Si(100) substrates by a pulsed Nd:YAG laser deposition. The laser beam is incident on the high-purity graphite targets. The films are grown using an energy density 3.8 J cm−2 at a laser repetition rate of 10 Hz. The nitrogen gas pressure in the chamber is 10.0 Pa. Morphology features of the films have been obtained by employing the technique of scanning electron microscopy. Auger electron spectroscopy has been used to obtain compositional information about the films. The N C composition ratio was found to vary from zero to 0.32 depending on deposition conditions. IR absorption spectra show two characteristic bands: a broad band composed of the graphite G-band and disordered D-band of carbon, and another associated with CN triple bonds. Raman spectra have also been used to characterize the films.

Development of Knowledge Sharing System for Agriculture Application

In this research, we construct a data sharing system for agriculture technology. The purpose of our research is to establish the methodology in order to share and inherit knowledge about agriculture. Our system collects data by two methods. One is automatic acquisition of the environment information by a sensor, and another is record of the work information by a farmer. In this paper, a skillful farmers knowledge is modeled as XML data. According to the data schema designed on the data model, the knowledge sharing system is implemented. This paper gives the outline of the structure of the system, and reported the result of the experience for collecting and accumulating and the design of a data sharing system are performed.

Solar energy for soil conditioning

Constant increase of energy consumption by growing population and shortening of natural resources will impose greater limitations of electric energy consumption by various treatment technologies. Shifting from large-scale treatment facilities powered from conventional sources to autonomic, small, and medium size installations supplied from renewables is one of the possible solutions. Results of ozone soil treatment are presented. PV panels supplied, on-site installation for soil treatment is proposed.

Synthesis of Platinum Nanodots Using Organ-Metal Solutions

In this study, platinum (Pt) nanodots with diameters of 73–142 nm were prepared using organ-metal solutions on silicon substrates by a heating process. The influence of heating conditions such as heating temperature and ambient gas pressure on the structural properties of the Pt nanodots was investigated. The size and shape of the Pt nanodots were measured using scanning electron microscopy and image analysis software. The results suggest that the diameter and shape of the Pt nanodots can be controlled by heating temperature. In addition, X-ray diffraction and X-ray photoelectron spectroscopy measurement results suggest that the crystallinity and atomic composition of the Pt nanodots can also be controlled by varying ambient gas pressure. Changing the ambient gas pressure while maintaining a constant temperature affected the growth of Pt and platinum silicide (PtSi) crystals in the Pt nanodots. Under atmospheric pressure and an ambient Ar pressure of 5000 Pa, a single Pt crystal was formed in the Pt nanodots. On the other hand, under low vacuum and an ambient Ar pressure of 700 Pa, Pt and PtSi crystals coexisted in the Pt nanodots.

Impression of high voltage pulses on substrate in pulsed laser deposition

We report deposition of diamondlike carbon (DLC) films on silicon substrates in vacuum by ablating a graphite target using KrF excimer laser. High voltage pulses synchronous with the ablating laser pulse were applied to substrates to improve the hardness and adhesion of the DLC film. Ions accelerated in the carbon plasma plume resulted in an increase of ion flux and energy that modified the film properties. The effect of high voltage pulses on the laser ablated plasma plume was investigated by the laser induced fluorescence method, and their effect on DLC films was examined using Fourier transform infrared atomic force microscopy, and nanoindentation. High voltage pulse applied to the substrate increased the sp3 constituent in the DLC film and enhanced the smoothness and hardness of the film.

Proposal of a Method to Evaluating Adaptability of Farmland for Cultivating Vegetables

In this paper, we propose a method to estimate an adaptability of environmental data on each farmland concerning with each cultivation of vegetables. We propose an actual method to represent a feature of a farmland. We define an adaptability of a farmland for vegetables as a value of differences between environmental data on the farmland and a condition of a standard manner of the cultivation. Since the size of observed data on each farmland is big, it is difficult to apply various algorithms for analysis to the data. Therefore, we present the method to compress such a big data into a simple value by indexing from observed values into-1, 0, or 1. Then, the method is applied to the data obtained by our cultivation experiment of tomatoes. From the result by comparing the values of adaptability obtained by experiments in 2013 and 2014, we show that the adaptability can be expected to have close relationship with growth of vegetables.

Development of Web System to Find Control Rules from Environmental Data on Farmland

In Japanese agriculture, skills of cultivations are losing by decreasing of population of farmers. To solve this problem, it is necessary to realize the system to inherit the farmers skills. The purpose of our research is to build a system which can be used to store skillful farmers actions and environmental changes. We develop a function for analyzing agricultural environment from the latest environmental data on farmland. We show that the system can support to analyze each attributes of environmental data. We execute a cultivation experiment in greenhouses, and apply the collected data to a learning algorithm.

Environmental application of electrical discharge for ozone treatment of soil

In this study, influence of ozone treatment on physical properties of soil was investigated. We used a quartz container for ozone treatment of soil. The amount of soil used for treatment was 100 g. Treating time was 90 minutes. Flow rate of ozone gas was 1.5 L/min. We measured characteristics of soil such as inorganic nutrient (NO3-N, NO2-N, and NH4-N), pH(H2O), fungi, DNA of soil, and exchangeable bases (Ca, K, Fe, and Al) before and after ozone treatment.