Takaomi Matsutani

Structural and optical properties of titanium dioxide films deposited by reactive magnetron sputtering in pure oxygen plasma

Titanium dioxide (TiO2) thin films were deposited on unheated quartz (SiO2) substrates in “pure oxygen” plasma by reactive radio-frequency (rf) magnetron sputtering. The structural and optical properties of deposited films were systematically studied by changing the deposition parameters, and it was very recently found that crystalline TiO2 films grew effectively in pure O2 atmosphere. For TiO2 films deposited at a rf power Prf of 200 W, x-ray diffraction patterns show the following features: (a) no diffraction peak was observed at a total sputtering pressure ptot of 1.3 Pa; (b) rutile (110) diffraction was observed at 4.0 Pa, (c) the dominant diffraction was from anatase (101) planes, with additional diffraction from (200), under ptot between 6.7 and 13 Pa. For the deposition at 140 W, however, crystalline films with mixed phases were observed only between 4.0 and 6.7 Pa. The peaks of both the deposition rate and the anatase weight ratio for the films produced at 140 W were found at ptot of approximately...

Room-temperature growth of crystalline indium tin oxide films on glass using low-energy oxygen-ion-beam assisted deposition

One of the long-standing problems to improve the resolution of organic electroluminescence devices has been related to the fabrication of very smooth, high-quality indium tin oxide (ITO) layers at room temperature. It seems that this problem could be solved by low-energy oxygen-ion-beam assisted electron-beam evaporation of ITO bulk material in vacuum. The oxygen ions were produced in an electron cyclotron resonance source with energies varied between 50 and 1000 eV. The growth rate changes from 0.04 to 0.23 nm/s. The structural, electrical and optical properties were characterized by x-ray diffraction, Rutherford backscattering, atomic force microscopy, Hall-effect and optical transmittance measurements. Crystalline structure, which depends only on the thickness of the deposited ITO films, can be easily obtained at room temperature. A very smooth surface of only 0.6 nm roughness (root mean square), almost one order smaller than that prepared by other methods, low resistivity of 7.0×10−4 Ω cm, high carrie...

Ion beam-induced chemical vapor deposition with hexamethyldisilane for hydrogenated amorphous silicon carbide and silicon carbonitride films

Abstract We report on the preparation of hydrogenated amorphous silicon carbide (a-SiC:H) film and silicon carbonitride (a-SiCN:H) film on Si (100) substrate by Ar ion beam-induced chemical vapor deposition (IBICVD) method attached with a bubbling system of hexamethyldisilane (HMDS). Ar ions and HMDS precursor with carrier gases of Ar or N 2 were introduced onto the substrate at room temperature. Fourier transform infrared (FT-IR) spectra revealed that an elimination of an organic compound and the formation of SiC, SiN and CN bonds can be promoted by increasing ion impact energy. Smooth surface with a lower roughness has been achieved when Ar ion energy increases from 50 to 300 eV.

Lattice location and annealing behavior of Mn implanted GaN

Abstract Gallium nitride (GaN) is a direct wide-band-gap semiconductor material, which can be used to produce blue-light-emitting diodes and lasers, high-temperature and high-power devices. While manganese (Mn) represents a potential acceptor in GaN, Mn-doped GaN may form an interesting diluted magnetic semiconductor. In this study, GaN was implanted at room temperature using 180 keV Mn+ ions to fluences ranging from 5×1015 to 3×1016 cm−2. Subsequent annealing was performed in a flowing N2 ambient, at 1050 °C for 12 min. The damage buildup and removal, as well as the lattice site location of Mn in GaN was studied by using Rutherford backscattering/channeling combined with particle induced X-ray emission. The angular scans around the 〈0 0 0 1〉 and 〈1 0 1 1〉 axial directions indicate that Mn mainly occupies substitutional Ga sites. During the thermal treatment, no significant redistribution of the implanted Mn ions was found.

Hydroxyapatite coatings using novel pulsed laser ablation methods

Abstract We developed two methods for depositing hydroxyapatite (HAp) coatings based on the pulsed laser ablation, laser irradiation and laser-assisted laser ablation (LALA) techniques. In laser irradiation, the HAp coatings were deposited in air. LALA involves both laser ablation and laser annealing using two laser beams. The assisting laser beam helped crystallize and anneal the deposited HAp layer. HAp coatings deposited using LALA remained intact during the Scotch ® tape test and grew in the simulated body fluid.

Ionization of hexamethyldisilane for SiC deposition

Abstract We developed the SiC deposition technique by using ion beam induced deposition. In this technique, hexamethyldisilane was excited through impact with Ar ions and fragmented ions were deposited on the substrate. In this work the fragmentation mechanism of hexamethyldisilane is studied using Mass Spectrometry. To discuss the effect of excitation energy, hexamethyldisilane was excited by impact with electrons. With an impact of electrons in an energy range of 10–70 eV, two types of fragmentation, namely, the Si–Si bond dissociation and the methyl radical loss, were observed. The formation of these fragment ions, most probably trimethylsilyl cations, contributed to SiC deposition.

Structural, electrical and optical properties of indium tin oxide films prepared by low-energy oxygen-ion-beam assisted deposition

Abstract Indium tin oxide (ITO) films were deposited onto fused silica (SiO 2 ) and microslide glass by concurrent electron-beam evaporation of ITO bulk materials and low-energy oxygen-ion-beam bombardment. The oxygen ions were produced using an electron cyclotron resonance source. The acceleration voltage was varied between 50 and 500 V and the current densities were between 20 and 100 μA/cm 2 . The growth rate changed from 0.04 to 0.24 nm/s. Deposition of ITO films was carried out at room temperature and 200 °C. The structural, electrical and optical properties were characterized by X-ray diffraction, atomic force microscopy, Hall-effect and optical transmission measurements. The results show that very smooth and crystalline ITO films with high conductivity and transparency can be achieved.

Flattening of Surface by Sputter-Etching with Low-Energy Ions

The thickness of the damaged layer on a GaAs surface induced by a focused 25 kV Ga+ ion beam (FIB) was reduced from ~24 nm to ~2.6 nm by finishing with low-energy Ar+ ions of 200 eV, which has been evaluated by cross-sectional observation under a transmission electron microscope (TEM). The finishing rendered the surface of the damaged layer significantly flatter. This flattening was found to be sensitive to the ion energy; a very smooth flat surface is obtained by sputter-etching with 200 eV Ar+ ions, whilst sputter-etching with 100 eV Ar+ ions causes GaAs particles to remain in the FIB-induced damage layer on the surface, and thus it is not flat.

Development of a parallel detection and processing system using a multidetector array for wave field restoration in scanning transmission electron microscopy.

A parallel image detection and image processing system for scanning transmission electron microscopy was developed using a multidetector array consisting of a multianode photomultiplier tube arranged in an 8 x 8 square array. The system enables the taking of 64 images simultaneously from different scattered directions with a scanning time of 2.6 s. Using the 64 images, phase and amplitude contrast images of gold particles on an amorphous carbon thin film could be separately reconstructed by applying respective 8 shaped bandpass Fourier filters for each image and multiplying the phase and amplitude reconstructing factors.

Formation of Aluminum Nitride Film for High Power Soft X-Ray Source Using Ion-Beam Assisted Deposition Method

An aluminum nitride (AlN) target for Al-Kα X-ray source with high power and long service life has been developed by N2 + ions assisted Al vapor deposition method (IBAD). The AlN film formations were carried out at the Al deposition rate varied from 2.0 nm/s to 0.15 nm/s with a fixed low-energy N2 + ion of 1 keV. The films were deposited on Cu substrate at room temperature. The AlN films were characterized by an X-ray diffraction, an electron probe X-ray microanalysis and a Knoop-hardness measurement. The AlN deposited at the Al deposition rate of 0.5 nm has a N/Al ratio of 0.4, a Knoop-hardness of ~1500 and a low resistance of ~0.2 . Comparison of durability test between the AlN target and a conventional Al target was performed. It has been revealed, after 500 hours under an electron bombardment of 300 mA at 20 kV, that there were no change of morphology and X-ray intensity on the AlN-surface whilst cracks due to the heat-cycle fatigue covered the Al-surface.