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Kazuhiro Nakamura

Bio: Kazuhiro Nakamura is an academic researcher from Kansai University. The author has contributed to research in topics: Silicon & Ion beam-assisted deposition. The author has an hindex of 8, co-authored 59 publications receiving 235 citations.


Papers
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TL;DR: In this article, the authors used an ion beam assisted deposition technique with an electron cyclotron resonance ion source for ionizing nitrogen gas and an electron beam evaporator for evaporating Ti metals.
Abstract: Cubic titanium nitride (TiN) films preferentially oriented to the (200) lattice plane were deposited onto (111) silicon wafers using an ion beam assisted deposition technique with an electron cyclotron resonance ion source for ionizing nitrogen gas and an electron beam evaporator for evaporating Ti metals. The resistivities of the TiN films were inversely proportional to the average size of the crystallites making up the TiN films and decreased with increasing substrate temperature and film thickness. TiN films thicker than 50 nm had resistivities around 30 µ Ω cm, slightly higher than the resistivities of TiN crystals.

48 citations

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TL;DR: According to the results of an experiment on hydrogen production using the reduced iron nanoparticles, the reaction efficiency of the hydrogen generation at a temperature of 673 K was more than 94% for the ideal amount of generated hydrogen.
Abstract: A recyclable energy cycle using a pulsed laser and base-metal nanoparticles is proposed In this energy cycle, iron nanoparticles reduced from iron oxides by laser ablation in liquid are used for hydrogen generation The laser energy can be stored in the base-metal nanoparticles as the difference between the chemical energies of iron oxide and iron According to the results of an experiment on hydrogen production using the reduced iron nanoparticles, the reaction efficiency of the hydrogen generation at a temperature of 673 K was more than 94% for the ideal amount of generated hydrogen

21 citations

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TL;DR: In this article, the surface of stainless steel SUS 304 was coated with dual titanium oxynitride (TiNO) layers using a nitrogen ion beam-assisted deposition technique, and three characteristic layers consisting of iron nitride, chromium nitride and nickel nitride were formed between the TiNO films deposited and the stainless steel.
Abstract: Surfaces of stainless steel SUS 304 were coated with dual titanium oxynitride (TiNO) layers using a nitrogen ion beam-assisted deposition technique. The N ions were accelerated at energy of 0.5–2.0 keV with an intensity of 0.1 mA/cm 2 on the substrate surface. First, a TiNO film was deposited on substrates at 700 °C, and subsequently, another TiN film was deposited on the previous TiNO film surface at 400 °C. Hydrogen carbon nitride, CrFe, and metal carbide M 23 C 6 were produced in the near-surface region of stainless steel during the TiNO deposition at 700 °C, and three characteristic layers consisting of iron nitride, chromium nitride and nickel nitride were formed between the TiNO films deposited and the stainless steel. These characteristic layers disappeared during deposition of the TiNO layer at a temperature of 400 °C.

19 citations

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TL;DR: In this article, a semi-insulating GaAs wafer was annealed at temperatures of 650-1000°C for 15 min, and the dominant defects were EL2 and EL6.
Abstract: Sulfur ions were implanted into a semi-insulating GaAs wafer at 50 keV at a dose of 1×1015 cm−2. The implanted GaAs wafer was annealed at temperatures of 650–1000 °C for 15 min. Deep levels were measured in regions with carrier concentrations lower than 3×1017 cm−3, after layers of various thicknesses were removed from the surface of the wafer. The dominant defects in samples annealed at temperatures lower than 850 °C were EL2 and EL6, while 1000 °C annealed samples exhibited isolated EL2 and EL3 defects. Isolated EL2 defects were observed in regions of carrier concentrations lower than 1×1017 cm−3, and EL3 defects were observed in regions of carrier concentrations higher than 2×1017 cm−3.

13 citations

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TL;DR: In this paper, an ion beam assisted deposition technique consisting of an electron beam evaporator for Ti evaporation and a microwave ion source for ionizing oxygen gas was used to accelerate the O ions to energies of 0.5-2.0 keV.
Abstract: Titanium oxide films were deposited on (1 0 0) silicon wafers using an ion beam assisted deposition technique consisting of an electron beam evaporator for Ti evaporation and a microwave ion source for ionizing oxygen gas. The O ions were accelerated to energies of 0.5–2.0 keV. The intensity of the O ion beam was 0.01 mA/cm 2 on the substrate. The deposited TiO 2 films were rutile O-deficient TiO 2 crystals preferentially oriented in the 〈1 1 0〉 direction with very high permittivity values approximately (100–160) e 0 . The permittivity increased with increasing 〈1 1 0〉 orientation texture.

12 citations


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Journal ArticleDOI
TL;DR: This absorber integrates both the plasmonic resonances and the dielectric-like loss and opens a path for the interesting applications such as solar thermophotovoltaics and optical circuits.
Abstract: A high-temperature stable broadband plasmonic absorber is designed, fabricated, and optically characterized. A broadband absorber with an average high absorption of 95% and a total thickness of 240 nm is fabricated, using a refractory plasmonic material, titanium nitride. This absorber integrates both the plasmonic resonances and the dielectric-like loss. It opens a path for the interesting applications such as solar thermophotovoltaics and optical circuits.

597 citations

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TL;DR: In this paper, the authors review how metal oxide-based gate dielectrics emerged from all likely candidates to become the new gold standard in the microelectronics industry, its different phases, reported electrical properties, and materials processing techniques, including carrier scattering, interface state passivation, phonon engineering, and nano-scale patterning.
Abstract: The move to implement metal oxide based gate dielectrics in a metal-oxide-semiconductor field effect transistor is considered one of the most dramatic advances in materials science since the invention of silicon based transistors. Metal oxides are superior to SiO 2 in terms of their higher dielectric constants that enable the required continuous down-scaling of the electrical thickness of the dielectric layer while providing a physically thicker layer to suppress the quantum mechanical tunneling through the dielectric layer. Over the last decade, hafnium based materials have emerged as the designated dielectrics for future generation of nano-electronics with a gate length less than 45 nm, though there exists no consensus on the exact composition of these materials, as evolving device architectures dictate different considerations when optimizing a gate dielectric material. In addition, the implementation of a non-silicon based gate dielectric means a paradigm shift from diffusion based thermal processes to atomic layer deposition processes. In this report, we review how HfO 2 emerges from all likely candidates to become the new gold standard in the microelectronics industry, its different phases, reported electrical properties, and materials processing techniques. Then we use specific examples to discuss the evolution in designing hafnium based materials, from binary to complex oxides and to non-oxide forms as gate dielectric, metal gates and diffusion barriers. To address the impact of these hafnium based materials, their interfaces with silicon as well as a variety of semiconductors are discussed. Finally, the integration issues are highlighted, including carrier scattering, interface state passivation, phonon engineering, and nano-scale patterning, which are essential to realize future generations of devices using hafnium-based high- k materials.

450 citations

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TL;DR: In this paper, the performance of three titanium nitride coatings: TiN, TiON, and TiAlN for biomedical applications were assessed in terms of their surface properties electrochemical corrosion in simulated body fluid and cytotoxicity.
Abstract: In the present study, the performance of three titanium nitride coatings: TiN, TiON, and TiAlN for biomedical applications were assessed in terms of their surface properties electrochemical corrosion in simulated body fluid and cytotoxicity. Layers of TiN, TiON and TiAlN were deposited onto CP–Ti substrates by DC reactive magnetron sputtering method using a combination of a Ti, Ti–Al targets and an Ar–N 2 mixture discharge gas. The presence of different phases was identified by XRD analysis. The morphology was determined through atomic force microscopy (AFM) imaging. The XPS survey spectra on the etched surfaces of TiN film exhibited the characteristic Ti2p, N1s, O1s peaks at the corresponding binding energies 454.5, 397.0, and 530.6 eV respectively. The characteristic Raman peaks were observed from the Laser Raman spectrometer. Platelet adhesion experiments were done to examine the interaction between blood and the materials in vitro. On Control samples (CP Ti), platelets were seen as aggregates, whereas on coated samples, platelets were seen as singles, without any significant spreading. Cytocompatibility studies of coated samples were carried out with bare titanium (CP Ti — ASTM B 348) as controls. L-929 mouse fibroblast cells were used for samples. All materials showed good cytocompatbility with cell lines used.

216 citations

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TL;DR: New magnetic Fe-based metal-organic frameworks (MOFs)/TiO2 composite for degrading pharmaceutical wastewater put forward was environment friendly material, which exhibited high TC degradation efficiency and excellent reusability.

154 citations

Journal ArticleDOI
TL;DR: Iridium-catalyzed selective α-dimethylation and α-methylation of ketones or phenylacetonitriles, using methanol as the methylating agent, were achieved and this method provides a very convenient direct route to α- methylated ketones, using meethanol.

126 citations