A5038177364- Semiconductor materials and devices
- Silicon Nanostructures and Photoluminescence
- Graphene research and applications
- Ion-surface interactions and analysis
- Electron and X-Ray Spectroscopy Techniques
- Carbon Nanotubes in Composites
- Diamond and Carbon-based Materials Research
- Nanowire Synthesis and Applications
- Silicon and Solar Cell Technologies
- Advanced Electron Microscopy Techniques and Applications
- Semiconductor materials and interfaces
- Laser Material Processing Techniques
- Thin-Film Transistor Technologies
- Photocathodes and Microchannel Plates
- Radiation Effects in Electronics
- Integrated Circuits and Semiconductor Failure Analysis
- Electrohydrodynamics and Fluid Dynamics
- Molecular Junctions and Nanostructures
- GaN-based semiconductor devices and materials
- Laser-induced spectroscopy and plasma
- Advanced Materials Characterization Techniques
- Plasma Diagnostics and Applications
- Advancements in Semiconductor Devices and Circuit Design
- Force Microscopy Techniques and Applications
- Mechanical and Optical Resonators
National Institute for Japanese Language and Linguistics
2025
National Institute of Advanced Industrial Science and Technology
2016-2024
Hachinohe Institute of Technology
1992-2023
Shizuoka University
2017-2023
University of Tsukuba
2010-2021
Friedrich-Alexander-Universität Erlangen-Nürnberg
2011-2020
National Institute for Materials Science
2018
Fraunhofer Institute for Integrated Systems and Device Technology
2015
Schott (Germany)
2015
Osaka University
2001-2011
Point sources exhibit low threshold electron emission due to local field enhancement at the tip. The development and implementation of tip emitters have been hampered by need position them sufficiently apart achieve enhancement, limiting number sites therefore overall current. Here we report (< 0.1 V/μm) multiple beams from atomically thin edges reduced graphene oxide (rGO). Field microscopy measurements show evidence for interference that are separated a few nanometers, suggesting emitted...
We report the first observation of vibrational Raman spectrum hydrogen molecules ${\mathrm{H}}_{2}$ in crystalline silicon treated with atoms at 400 \ifmmode^\circ\else\textdegree\fi{}C. The observed room temperature exhibits a frequency shift around $4158{\mathrm{cm}}^{\ensuremath{-}1}$ and very broad half-width approximately $34{\mathrm{cm}}^{\ensuremath{-}1}$. An isotope was also detected $2990{\mathrm{cm}}^{\ensuremath{-}1}$ deuterium shifts lines are close agreement those reported for...
Low-temperature direct synthesis of thick multilayered hexagonal-boron nitride (h-BN) on semiconducting and insulating substrates is required to produce high-performance electronic devices based two-dimensional (2D) materials. In this study, h-BN with a thickness exceeding 5 nm was directly synthesized quartz Si at low temperatures, between 400 500 °C, by inductively coupled plasma-enhanced chemical vapor deposition using borazine as the precursor material. The quality crystals were...
A single layer of graphene with dimensions 20 mm × was grown directly on an insulating substrate by chemical vapor deposition using Ga catalysts. The showed highly homogeneous crystal quality over a large area the substrate. measured Raman spectroscopy and found to improve increasing density reaction area. High-resolution transmission electron microscopy observations that synthesized had perfect atomic-scale structure within its grains, which ranged in size from 50 nm 200 nm.
A gradual downshift and asymmetric broadening of the Si optical phonon peak were observed by Raman scattering measurements continuously thermally oxidized silicon nanowires (SiNWs) synthesized laser ablation. This can be interpreted confinement effect. Further thermal oxidation produced a reverse change; namely, an upshift peak. is considered to due compressive stress since this was relieved removing oxide layers formed around SiNW cores, resulting in
A graphene-oxide-semiconductor (GOS) planar-type electron source was fabricated by direct synthesis of graphene on an oxide layer via low-pressure chemical vapor deposition. It achieved a maximum emission efficiency 32.1% suppressing the inelastic scattering within topmost gate electrode using electrode. In addition, current density 100 mA/cm2 observed at 16.2%. The energy spread well fitted to Maxwell-Boltzmann distribution, which indicates that emitted electrons are thermally equilibrium...
Abstract A method to measure the electrical resistivity of materials using magnetic- force microscopy (MFM) is discussed, where MFM detects magnetic field caused by tip-oscillation-induced eddy current. To achieve high sensitivity, a cantilever oscillation frequency preferable, because it induces large currents in material. Higher-order resonance modes lead higher frequency. discuss such high-order-mode oscillation, differential equation governing high-order mode formulated, and an...
From the analysis of ratio D peak intensity to G in Raman spectroscopy, electron beam irradiation with energies 100 eV was found induce damage single-layer graphene. The becomes larger decreasing energy. Internal strain graphene induced by under is further evaluated based on shifts. dose-dependent internal approximately 2.22% cm2/mC at and 2.65 × 10−2% 500 eV. showed strong dependence
Highly efficient electron emission of 48.5% was demonstrated by a graphene/oxide/semiconductor (GOS) structure. The main factors contributing to this performance were investigated analyzing the energy distributions emitted electrons and current conduction mechanism through oxide layer. level lower tail distribution 2.4–2.6 eV above work function graphene electrode, indicating that gate electrode does not affect efficiency. In addition, Fowler–Nordheim (FN) tunneling dominant in layer when...
We have found that hydrogen exists in molecular form crystalline silicon treated with atoms the downstream of a plasma. The vibrational Raman line molecules is observed at $4158{\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ for samples hydrogenated between 180 and 500 \ifmmode^\circ\else\textdegree\fi{}C. assignment confirmed by its isotope shift to $2990{\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ deuterium atoms. intensity has maximum hydrogenation 400 broad asymmetric. It consists least two...
Local vibrational modes of boron (B) in silicon nanowires (SiNWs) synthesized by laser ablation were observed at about 618 and 640cm−1 Raman scattering measurements. Boron doping was performed during the growth SiNWs. Fano [Phys. Rev. 124, 1866 (1961)] broadening also Si optical phonon peak. These results prove that B atoms doped Hydrogen (H) passivation acceptors SiNWs investigated. A broad peak around 650–680cm−1 after hydrogenation, demonstrating dopants passivated formation well-known...
The phonon confinement and self-limiting oxidation effects of silicon nanowires (SiNWs) synthesized by laser ablation were investigated. size SiNWs was controlled the synthesis parameters during subsequent thermal oxidation. Thermal increases thickness SiNWs’ surface oxide layer, resulting in a decrease their crystalline Si core diameter. This effect causes downshift asymmetric broadening optical peak due to confinement, while excess an upshift compressive stress. stress retarded effect....
Phosphorus (P) doping was performed during the synthesis of silicon nanowires (SiNWs) by laser ablation. At least three types signals were observed electron spin resonance (ESR) at 4.2K. into substitutional sites crystalline Si in SiNWs demonstrated detection an ESR signal with a g value 1.998, which corresponds to conduction electrons Si, and energy-dispersive x-ray spectroscopy spectrum PKα line. The results also revealed presence defects. These defects partially passivated hydrogen oxygen atoms.
Graphene was used as the topmost electrode for a metal-oxide-semiconductor planar-type electron emission device. With several various layers, graphene gate on thin oxide layer directly deposited by gallium vapor-assisted chemical vapor deposition. The maximum efficiency of emission, defined ratio anode current to cathode current, showed no dependency thickness in range from 1.8 nm 7.0 nm, indicating that scattering inside is practically suppressed. In addition, high density 1–100 mA/cm2...
In this work, a planar electron emission device based on graphene/hexagonal boron nitride (h-BN)/n-Si heterostructure is fabricated to realize highly monochromatic from flat surface. The h-BN layer used as an insulating suppress inelastic scattering within the device. energy spread of using 0.28 eV full-width at half-maximum (FWHM), which comparable conventional tungsten field emitter. characteristic spectral shape distributions reflected distribution in conduction band n-Si substrate....
Carbon nanotube (CNT) cathode surfaces have been exposed to Ar plasma and the emission characteristics were measured. When a CNT was for 3 min, improved. The current increased after an treatment min by three orders of magnitude from 9.0×10−5 3.3×10−1 mA/cm2 at 4.0 V/μm with decrease in turn-on voltage 3.3 1.7 V/μm. According scanning electron microscopy images, entangled bundles raveled out treatment.
Size control of silicon nanowires (SiNWs) synthesized by laser ablation a Si target with iron or nickel as catalysts were investigated changing the synthesis parameters such content catalyst in targets and power during synthesis. The diameter length SiNWs significantly depended on parameters, i.e. size can be controlled parameters. Manipulation was also performed observation scanning electron microscope. By degree charge-up for free-standing adjacent intertwined at an edge substrate,...
Pt nanowires were fabricated using electron-beam (EB)- and focused-ion-beam (FIB)-induced deposition. The resistance of the EB-deposited was high (≈10 7 Ω) as deposited increased markedly when cooled down. observed temperature dependence wires indicates that electron transport in is dominated by variable range hopping (VRH). Coulomb oscillations at temperatures up to ≈200 K for simultaneously with VRH. Postannealing effective reduce resistance. FIB-deposited nanowires, contrast, hardly...
Codoping of boron (B) and phosphorus (P) atoms was performed during the synthesis silicon nanowires (SiNWs) by laser ablation. The observation a local vibrational mode B clearly showed doping in codoped SiNWs, while Fano broadening due to heavy disappeared, indicating compensation P donors. electrospin resonance signal conduction electrons also disappeared acceptors. These results indicate that codoping achieved SiNWs
Topography and leakage current maps of TiO2 films grown by atomic layer deposition on RuO2 electrodes using either a TiCl4 or Ti(O-i-C3H7)4 precursor were characterized at nanoscale conductive force microscopy (CAFM). For both films, the flows mainly through elevated grains not along grain boundaries. The overall CAFM is larger more localized for TiCl4-based (0.63 nm capacitance equivalent oxide thickness, CET) compared to Ti(O-i-C3H7)4-based (0.68 CET). Both have physical thickness ∼20 nm....
The electron emission properties of planar-type devices based on a graphene-oxide-semiconductor (GOS) structure before and after vacuum annealing were investigated. fluctuation the current was around 0.07%, which is excellent stability compared to conventional field emitter array. GOS operable in very low 10 Pa without any deterioration their properties. Improvement achieved by at 300 °C. efficiency type reached 2.7% from 0.2% annealing. work function graphene electrode found decrease 0.26...