A5063423155- Silicon Nanostructures and Photoluminescence
- Thin-Film Transistor Technologies
- Nanowire Synthesis and Applications
- Semiconductor materials and devices
- Silicon and Solar Cell Technologies
- Integrated Circuits and Semiconductor Failure Analysis
- Advanced Surface Polishing Techniques
- Ion-surface interactions and analysis
- Minerals Flotation and Separation Techniques
- Optical Coatings and Gratings
- Copper Interconnects and Reliability
- Semiconductor materials and interfaces
- Silicon Carbide Semiconductor Technologies
- Cyclone Separators and Fluid Dynamics
- Nanopore and Nanochannel Transport Studies
- Diamond and Carbon-based Materials Research
- Photonic Crystals and Applications
- Rheology and Fluid Dynamics Studies
- Laser-Ablation Synthesis of Nanoparticles
- Marine Biology and Environmental Chemistry
- Boron and Carbon Nanomaterials Research
- Quantum Dots Synthesis And Properties
- Coal Combustion and Slurry Processing
- Dental Implant Techniques and Outcomes
- Hydrogen's biological and therapeutic effects
Tokyo Dental College
2023
New York University
2023
Osaka University
2012-2022
Kindai University
2020
Japan Science and Technology Agency
2008-2019
University of Žilina
2017
Osaka Research Institute of Industrial Science and Technology
2012-2017
Asics (Japan)
2017
Nihon University
2016
Kitasato University
1981
Si and its oxide are nonpoisonous materials, thus, it can be taken for medical effects. We have developed a method of generation hydrogen by use reactions nanopowder with water in the neutral pH region. is fabricated simple bead milling method. reacts to generate even cases where set at region between 7.0 8.6. The rate strongly depends on case 8.0, ∼55 ml/g which corresponds that contained approximately 3 L saturated hydrogen-rich generated 1 h. reaction greatly increases pH, indicating...
The initial reaction of Si nanopowder with water to generate hydrogen is investigated using FT-IR and XPS measurements. fabricated the simple beads milling method. For HF-etched nanopowder, strong peaks due Si-H Si-H2 stretching vibrational modes a weak shoulder peak Si-H3 are observed. Although no oxide observed in 2p spectrum, HSiO2 HSiO3 species observable. generation rate greatly increases pH, indicating that reacting hydroxide ions (OH− ions). After reaction, intensities SiH SiH2...
A nanocrystalline Si layer can be formed by the surface structure chemical transfer (SSCT) method in which a platinum mesh is instantaneously contacted with polycrystalline wafers immersed hydrogen peroxide plus hydrofluoric acid solutions. The after SSCT possesses an ultra-low reflectivity. 100–150 nm thickness, and gives photoluminescence peak maximum at ∼670 nm, indicating band-gap widening. minority carrier lifetime of as-sliced greatly increases most probably due to enlargement band-gap.
Abstract 19.5% conversion efficiency crystalline silicon (Si) solar cells having simple structure without antireflection coating have been fabricated using the surface chemical transfer method which produces a nanocrystalline Si layer simply by contacting catalytic platinum with wafers in hydrogen peroxide plus hydrofluoric acid solutions. The reflectivity becomes less than 3% after due to formation of black Si. Deposition phosphosilicate glass and heat treatment at 925 °C performed for...
Electrical characteristics and physical properties of 8–10 nm silicon dioxide (SiO2) films formed on Si (100) substrates by use the nitric acid oxidation method at ∼120 °C have been investigated. The atomic density SiO2 layer increases with HNO3 concentration. Fourier transformed infrared absorption measurements show that higher concentration, layer. From Fowler–Nordheim plots, barrier height SiO2/Si interface is found to increase leakage current flowing through decreases concentration...
We have developed a surface structure transfer method by use of the catalytic activity platinum (Pt). When Pt mesh contacts Si wafers immersed in HF plus H2O2 solution, oxidation and its dissolution instantaneously proceed, resulting formation inverted on Si. The etching depth is proportional to immersion time, indicating reaction-limited mechanism. reaction rate constant concentration H2O2, showing that rate-determining step. Nanocrystalline formed whole surfaces including non-contacted...
By contact of platinum catalyst with Si wafers immersed in H2O2 plus HF solutions, ultra-low reflectance surfaces can be produced. The results from the formation a nanocrystalline (nc-Si) layer ∼300 nm thickness. A porosity-graded optical model consisting 19 sublayers for nc-Si layer, which is determined SEM and TEM observations, fitting ellipsometric spectra, found to well explain properties. dielectric function each sublayer calculated Bruggeman effective medium approximation using...
Si surfaces with reflectivity less than 3% are produced on pyramidal textured single crystalline wafers, taking 30 s, by use of the surface structure chemical transfer (SSCT) method. The solar cells <Ag/nanocrystalline Si/n+-Si/pyramidal p-Si substrate (180 μm)/Ag> show an 18.1% conversion efficiency and a high short-circuit photocurrent density 38.6 mA/cm2 in spite absence antireflection coating. Phosphosilicate glass for formation pn-junction possesses excellent passivation effect...
We have developed a rapid abrasive-free SiC planarization method which simply involves contact of rotating Pt disc electrode with wafers immersed in an HF solution and application 3 V to the respect reference Ag electrode. In this method, no bias voltage is necessary apply SiC. After polishing for h using surface roughness Ra value 7.91 nm (500 × 500 nm2 area) mechanically polished n-type 4H-SiC (000-1) decreases 0.12 without formation damaged layer. From XPS measurements, ∼0.4 thick SiO2...
Background: Hierarchical micro-nano structured topography along with surface chemistry modifications of dental implants have been suggested to positively contribute the osseointegration process.However, effect such on molecular response as well bone formation rate and quality are still unclear, especially in early healing period.This study aimed evaluate coating a double acid etched (DAE) implant nano-sized (20 nm) hydroxyapatite (Nano) respect gene expression, histologic parameters,...
A 19.8% conversion efficiency has been achieved by formation of a nanocrystalline Si layer on the front surface and submicron‐textured reflector rear monocrystalline solar cells. The with thickness ∼200 nm formed structure chemical transfer (SSCT) method significantly decreases reflectance to less than 3%, while metal‐assisted etching (MACE) enhances light absorption inside Si. Both reaction rates SSCT MACE methods do not depend crystal orientations, therefore, these are applicable...
We have developed a fast planarization method of 6H–SiC (0001) Si-faced surfaces using electrochemical reactions. In this method, working electrode rotating Pt disc is physically contacted with an SiC wafer immersed in HF solution, and potential 2 or 3 V respect to the Ag/AgCl reference applied disk electrode. After process voltage for 1 h, relatively flat 0.09 nm average roughness (Ra) value are obtained, but ∼ carbon-rich layer present on surfaces. A subsequent h almost completely removes...
Abstract Si nanopowder is fabricated using the simple beads milling method. Fabricated reacts with water in neutral pH region between 7 and 9 to generate hydrogen. The hydrogen generation rate greatly increases pH, while does not change after reaction. In case of reactions strong alkaline solutions ( eg pH13.9), 1600 mL generated from 1 g a short time 15 min). When etched HF immersed ethanol, green photoluminescence (PL) observed, it attributed band-to-band transition nanopowder. without...
We are developing a superconducting magnetic separation system to remove scale or iron oxide from boiler feedwater in thermal power plants. The reduction of improves energy conversion efficiency plants and reduces discharged CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . have studied suitable installation locations operation conditions examined the ability located near where water is at high temperatures pressures. concluded that...
The present paper deals with the photoluminescence (PL) of multicolor silicon (MC-Si) – a nanocrystalline layer produced by surface structure chemical transfer (SSCT) method on p-type Si. PL behaviours recorded at room temperature are compared ∼500-nm-thick porous Si prepared electrochemically in HF + methanol solution same substrate. spectra shifted to higher energy comparison MC-Si. records were fitted Gaussian curves. We attribute band maximum 2.3 eV own luminescence ∼2.5-nm-thick grains...