A5011720105- Thermal properties of materials
- Advanced Thermoelectric Materials and Devices
- Transition Metal Oxide Nanomaterials
- Neural Networks and Applications
- Semiconductor materials and devices
- Advanced Memory and Neural Computing
- Gyrotron and Vacuum Electronics Research
- Laser Material Processing Techniques
- Gas Sensing Nanomaterials and Sensors
- Thermography and Photoacoustic Techniques
- ZnO doping and properties
- CCD and CMOS Imaging Sensors
- Thermal Radiation and Cooling Technologies
- Advanced Surface Polishing Techniques
- Laser-induced spectroscopy and plasma
- Thermal and Kinetic Analysis
- Metal and Thin Film Mechanics
- Chalcogenide Semiconductor Thin Films
- Crystallography and Radiation Phenomena
- Thermodynamic and Structural Properties of Metals and Alloys
- Diamond and Carbon-based Materials Research
- Silicon Carbide Semiconductor Technologies
- Online and Blended Learning
- Advanced materials and composites
- Phase-change materials and chalcogenides
National Institute of Advanced Industrial Science and Technology
2015-2025
Aoyama Gakuin University
2021-2024
Waseda University
2021
Tokyo City University
2020
Osaka University
2020
Nara Institute of Science and Technology
2020
Tohoku Fukushi University
2016
Yamaguchi University
2014
National Institute of Technology, Toyota College
2013
Tohoku University
1997-2011
Samples of the carbonaceous asteroid Ryugu were brought to Earth by Hayabusa2 spacecraft. We analyzed 17 samples measuring 1 8 millimeters. Carbon dioxide-bearing water inclusions are present within a pyrrhotite crystal, indicating that Ryugu's parent formed in outer Solar System. The contain low abundances materials at high temperatures, such as chondrules and calcium- aluminum-rich inclusions. rich phyllosilicates carbonates, which through aqueous alteration reactions temperature, pH,...
The simultaneous realization of low thermal conductivity and high thermoelectric power factor in materials has long been the goal for social use high-performance modules. Nanostructuring approaches have drawn considerable attention because success reducing conductivity. On contrary, enhancement factor, namely, increase Seebeck coefficient electrical conductivity, difficult. We propose a method by introducing coherent homoepitaxial interfaces with controlled dopant concentration, which...
Thermal conductivity of a 300-nm-thick VO2 thin film and its temperature dependence across the metal–insulator phase transition (TMIT) were studied using pulsed light heating thermoreflectance technique. The Mo/VO2/Mo films with thickness 300 nm prepared on quartz glass substrates: former was used for characterization electrical properties, latter thermal measurement. deposited by reactive rf magnetron sputtering V2O3 target an Ar–O2 mixture gas at 645 K. consisted single as confirmed X-ray...
We develop transparent epitaxial SnO2 films with low thermal conductivity and high carrier mobility by domain engineering using the substrates symmetry: intentional control of size defect density between crystal domains. The on r-Al2O3 (a symmetry substrate) exhibit a twice higher than c-Al2O3 substrate), resulting in larger thermoelectric power factor r-Al2O3. This difference is likely attributed to Furthermore, both samples almost same conductivities (∼5.1 ± 0.4 W m−1 K−1 for SnO2/r-Al2O3...
This study demonstrates a simultaneous realization of ultralow thermal conductivity and high thermoelectric power factor in epitaxial GeTe thin films/Si substrates by combination the interface introduction domain engineering suppression Ge vacancy generation point defect control. We formed Te-poor films having low-angle grain boundaries with misorientation angle close to 0° or twin interfaces 180°. The control defects gave rise lattice ∼0.7 ± 0.2 W m-1 K-1. value was same order magnitude as...
We investigated the thermal conductivity of 200-nm-thick amorphous indium–gallium–zinc-oxide (a-IGZO) films. Films with a chemical composition In:Ga:Zn= 1:1:0.6 were prepared by dc magnetron sputtering using an IGZO ceramic target and Ar–O2 gas. The carrier density films was systematically controlled from 1014 to >1019 cm-3 varying O2 flow ratio. Their Hall mobility slightly higher than 10 cm2·V-1·s-1. Those sandwiched between 100-nm-thick Mo layers; their diffusivity, measured pulsed light...
The thermal conductivities of c- and a-axis-oriented zinc oxide (ZnO) thin films with nominal thicknesses 100, 200, 300 nm are investigated. ZnO were synthesized by radio frequency magnetron sputtering on the r-plane sapphire substrates, respectively. epitaxial relationship between film c-plane substrate is (0001)[11¯00] || (0001)[112¯0], that (112¯0)[11¯00] (011¯2)[112¯0]. c-axis-oriented has a columnar structure, whereas single domain-like structure significantly flat surface. conductivity...
This study presents the material design of Si1−xGex epitaxial films/Si for thin film thermoelectric generators (TFTEGs) by investigating their properties. The films composed group-IV elements are advantageous due to compatibility with Si process. We fabricated various controlled x values and strains using growth methods. Ge without exhibited highest power factor (∼47 μW cm−1 K−2) among strain-controlled (x ≠ 1) films, which is higher at room temperature than SiGe alloy-based bulks ever...
Metallic multilayers play a pivotal role in spintronics and also have recently attracted attention as spin-caloritronic materials for energy conversion, but their thermoelectric performance has not been quantified. This study of Fe/Pt presents method to evaluate the figure merit transverse conversion thin-film stacks. A multilayered structure reduces thermal conductivity notably enhances merit. Interestingly, epitaxial exhibit better than polycrystalline counterparts, due higher coefficient...
The microstructures of Cu/diamond interfaces prepared by surface-activated bonding at room temperature are examined cross-sectional scanning transmission electron microscopy (STEM). A crystalline defect layer composed Cu and diamond with a thickness approximately 4.5 nm is formed the as-bonded interface, which introduced irradiation an Ar beam during process. No observed 700 °C annealed attributed to recrystallization due high-temperature annealing Instead layer, mating interface copper...
A transparent thermoelectric material requires not only high performance but also optical transmittance. However, in nanostructured materials, the nanostructure interface brings trade-off relationship between thermal conductivity and We propose an approach for simultaneous control of transmittance epitaxial films, where carriers can be smoothly transported. This is realized by design based on three strategies: (1) a large atomic mass difference at heterointerface low conductivity; (2) with...
We investigated the dependence of thermal boundary resistance W/Al 2 O 3 interface in /W three-layered thin films on morphology. The layered structures, Al layers with thicknesses from 1 to 50 nm covered by top and bottom W a thickness 100 nm, were fabricated magnetron sputtering using target (99.99%) an (99.99%). fabrication polycrystalline amorphous was confirmed structural analysis. morphology layer/Al layer layer/top interfaces showed wavelike structure roughness about nm. Thermophysical...
This paper shows how computationally-expensive problems like image processing can be handled in real time with little hardware by neuron-MOS (/spl upsi/MOS) circuit technology. In digital signal processing, real-world data (analog, massive quantities, low-precision and ambiguous) are A/D converted upon acquisition, including inherent noise distortion, then bit-by-bit computed based on rigorous Boolean algebra. moving-image for instance, this requires extraordinary computational powers of...
Abstract To investigate the thermal-switching properties of Pd-catalyzed Ni–Mg alloy films, we conducted in situ analyses films’ electrical, optical, and thermal through hydrogen gasochromic reactions. These reactions allow films to reversibly switch between metallic (dehydride) semiconductor (hydride) phases. The conductivities states were found be 14 1.0 W m −1 K , respectively. By applying Wiedemann–Franz law, attributed significant decrease conductivity during hydrogenation reduction...
Abstract Thermal conductivity switching in Pd-catalyzed Gd hydride films was investigated using situ analyses of electrical, optical, structural, and thermophysical properties upon gasochromic hydrogenation/dehydrogenation at room temperature. These reactions allow the to reversibly switch between metallic (GdH 2 ) phase hydrogenated state semiconductor 3 dehydrogenated state. We fabricated three-layered comprising Pd (5 nm)/Gd or GdH (300 nm)/Mo (100 nm) DC magnetron sputtering Pd, Gd, Mo...
Engineering the thermal conductivities of amorphous materials is important for management various semiconducting devices. However, controlling heat carriers—long-range propagating propagons and short-range hopping diffusons—in disordered lattices difficult because carriers are strongly correlated with lattice disorder. To clarify relationship between disorder conduction, we must simultaneously investigate local structures hidden in a system microscopic transport characteristics diffusons....
Investigating how the thermal transport properties of iron change under extremely high pressure and temperature conditions, such as those found in Earth's core, is a major experimental challenge. Over past decade, there has been great deal discussion debate surrounding conductivity iron-based core its evolution. One reason for this may be variability experimentally obtained at pressures temperatures. In study, we present results measuring hexagonal-closed-pack (hcp) over wide...
The influence of dislocation density and impurities on the thermal conductivity epitaxial GaN thin films c-plane sapphire substrates was studied. with nominal thicknesses 100, 300, 1500 nm were fabricated by reactive direct current magnetron sputtering using a Ga metal target mixture gas Ar N2. A 300-nm-thick film also Ar–N2–H2. For all 300- 1500-nm-thick films, growth confirmed from sixfold symmetry spots in pole figure selected area electron diffraction patterns. Rocking curves GaN(0002)...
The database system for thermophysical property data, which has been developed by the National Metrology Institute of Japan (NMIJ), is evolved to store comprehensive information on thin films. Since a film identified not only its constituent elements, phases, or compositions but also method synthesis, strategy storing all thin-film specimens adopted when data are measured NMIJ. In addition, new criteria material classification in our introduced systematically manage multilayer specimens. For...
Abstract High power lasers can weaken, spall, melt and vaporize natural earth materials with thermal spallation being the most energy efficient rock removal mechanism.The interesting focus of recent laser drilling research is on developing a technique to drill large deep holes in rocks, potential application gas oil well having rate higher than that conventional rotary as flame-jet spallation.Research also focused using make perforation channels improved permeability perforated...
The thermoelectric properties of epitaxial Ge films on Si(001) substrates were investigated, where the film crystallinity was controlled using various growth techniques established in large-scale integration research. exhibited substantially lower thermal conductivities than that bulk Ge. Unlike carrier mobility with strong dependence, Seebeck coefficient similar to high value and less dependence. This demonstrates inherently high-carrier-mobility can exhibit reduced conductivity a power...