A5088217399- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Ion-surface interactions and analysis
- Integrated Circuits and Semiconductor Failure Analysis
- Semiconductor materials and devices
- Crystallography and molecular interactions
- Electron and X-Ray Spectroscopy Techniques
- Semiconductor Quantum Structures and Devices
- Metal and Thin Film Mechanics
- Terahertz technology and applications
- Advancements in Semiconductor Devices and Circuit Design
- Diamond and Carbon-based Materials Research
- Advanced Electron Microscopy Techniques and Applications
- Superconducting and THz Device Technology
- Magnetic properties of thin films
- Photonic and Optical Devices
- GaN-based semiconductor devices and materials
- Perovskite Materials and Applications
- Quantum and electron transport phenomena
- Thermal Expansion and Ionic Conductivity
- Advanced Memory and Neural Computing
- Nanofabrication and Lithography Techniques
- Magnesium Oxide Properties and Applications
- Magnetic Properties and Applications
- Radiation Effects in Electronics
University of Shiga Prefecture
2008-2024
Kyushu University
2021-2024
Kumamoto University
2019-2020
Shiga University
2019
Osaka University
1998-2009
Japan Science and Technology Agency
2007-2008
Joint Laboratory for Extreme Conditions Matter Properties
1999-2000
Ion conductors comprising noncentrosymmetric frameworks have emerged as new functional materials. However, strongly correlated polarity functionality and ion transport not been achieved. Herein, we report a ferroelectric proton conductor, K2MnN(CN)4·H2O (1·H2O), exhibiting the strong correlation between its polar skeleton conductive ions that generate anomalous ferroelectricity via proton-bias phenomenon. The application of an electric field ±1 kV/cm (0.1 Hz) on 1·H2O at 298 K produced...
We have investigated the emission of terahertz electromagnetic wave from an undoped GaAs (200nm)∕n-type (3μm) epitaxial layer structure (i-GaAs∕n-GaAs structure), where doping concentration n-GaAs is 3×1018cm−3. It found that first-burst amplitude i-GaAs∕n-GaAs sample remarkably larger than a crystal, which means i-GaAs enhances intensity. The sample, by tuning pump-beam energy to higher side, exceeds i-InAs crystal known as one most intense emitters. We, therefore, conclude useful obtain emission.
Recently, non-crystalline coordination materials have been shown to represent a versatile class of functional materials. However, such incorporating metal complex clusters remained largely unexplored. Herein, we demonstrate that luminescent tetranuclear ReV cluster melts at 489 K, with the structure being maintained in corresponding supercooled ionic liquid phase.
We synthesized a (1-propylpyridinium)2 [ReN(CN)4 ]-type organic-inorganic hybrid exhibiting water-vapor-induced drastic structural changes of the ]2- assemblies. Specifically, upon exposure to water vapor, dehydrated nitrido-bridged chains were converted hydrated cyanido-bridged tetranuclear clusters via rearrangements large molecular building units in crystals. These switchable assembly forms display substantially different photo-physical properties, although both cases emission is caused...
The formation of porous structures nanometre size (nanoporous structures) on germanium (Ge) surfaces by focused ion beam (FIB) irradiations was investigated using various FIB conditions such as species, irradiation energies, total fluences, fluence rates, and incident angles. FIB-irradiated regions were observed a scanning electron microscope an atomic force microscope. It is found that, Ga (Ga FIB) at energy 100 keV, the irradiated Ge surface swelled up to 2 × 1017 cm−2 with nanoporous then...
Two-dimensional Hofmann-type coordination polymers of type Mn(H2O)2[Pd(CN)4]·xH2O (1·xH2O; x = 0, 1, and 4), Mn(H2O)(MeOH)[Pd(CN)4]·2MeOH (2·2MeOH), Mn(MeOH)2[Pd(CN)4]·MeOH (3·MeOH) have been synthesized. The homosolvent-bound 1·4H2O, 1·H2O, 3·MeOH consist undulating layer structures, whereas the structure heterosolvent-bound 2·2MeOH consists “Janus-like” flat layers in which water-bound MeOH-bound-sides are present. 1·4H2O 1·H2O exhibited anisotropic two-dimensional thermal expansions...
Layer flexibility in two-dimensional coordination polymers (2D-CPs) contributes to several functional materials as it results anisotropic structural response external stimuli. Chemical modification is a common technique for modifying layer structures. This study demonstrates that crystal morphology of cyanide-bridged 2D-CP type [Mn(salen)]2 [ReN(CN)4 ] (1) consisting flexible undulating layers significantly impacts the configuration and assembly. Nanoplates 1 showed an in-plane contraction...
A reflective waveplate with subwavelength grating structure of the photoresist was fabricated using two-beam interference technology. From optical measurement, it is found that phase retardation element (period: 400 nm, fill factor: 0.5, depth: 280 nm) almost same as transmission around twice deeper depth 450 nm). This because length transmissive one by reflection. By changing period and to 285 nm 300 respectively, also confirmed from experimental result exceeded 150° for wavelength at...
Chemical responsivity in materials is essential to build systems with switchable functionalities. However, polarity-switchable are still rare because inducing a symmetry breaking of the crystal structure by adsorbing chemical species difficult. In this study, we demonstrate that molecular organic-inorganic hybrid (NEt4)2[MnN(CN)4] (1) undergoes polarity switching induced water vapor and transforms into example proton-conducting second-harmonic-generation-active material. Centrosymmetric 1...
Abstract Anisotropic negative thermal expansion is a valuable property of solid‐state materials, influencing their micromechanical and functional response. Two flexible two‐dimensional (2D) cyanide‐bridged coordination polymers (CPs) type [Fe(salen)] 2 [M(CN) 4 ] (M=MnN ( FeMnN ) Pt FePt )) were synthesized. Their anisotropic expansions was strongly linked to relaxations node distortions in + units. Comparison with the [Mn(salen)] analogues indicated shorter bond lengths around iron(III),...
The negative thermal expansion (NTE) of solid-state materials is significance in various fields, but a very rare phenomenon. In this study, we carried out meta-analysis for the anisotropic behavior fifteen two-dimensional coordination polymers [M(salen)]2[M′(CN)4(solvent)] (M = Mn, Fe; M′ MnN, ReN, Pt, Pt(I2)x; x 0.18, 0.45, 0.85, 1.0; solvent H2O, MeOH, MeCN) with newly synthesized [Fe(salen)]2[MnN(CN)4(MeCN)]. Consequently, successfully demonstrate unusual NTE undulating layers by an...
We have measured the ballistic length l bFIB of a GaAs/AlGaAs sample using electron focusing effect and mean free path eFIB narrow channel, both formed by focused ion beam (FIB) irradiation, to estimate damage induced FIB irradiation. It is observed that scattering centers are which exhibit dependence on density, unlike due grown-in defects. The FIB-induced distribute far beyond distance spot size. This may be exponential tail distribution FIB.
The benefit of combining soft X-ray magnetic circular dichroism and photoelectron microscopy is demonstrated by applying this combination to the observation domain structures rectangular microstructures. size aspect-ratio dependence transformation field pulses investigated. switching mechanism, which very important in application storage, discussed terms between saturated vortex structures.
A new method to fabricate single-electron tunneling structures with magnetic materials using focused ion beam (FIB) sputtering and lithography techniques is proposed. By this method, a small metal island size comparable or smaller than the FIB diameter, connected source drain electrodes via tunnel junctions, can be fabricated. In present article, some important parameters in such as yields of photoresist (AZ 1350) nickel (Ni) layers, were measured cross-sectional images grooves delineated on...
As a new method for fabricating gallium nitride (GaN) layers at the outer surface of silicon (SiN) films, low-energy Ga ion irradiation on SiN films was performed, and composition chemical-bond nature irradiated surfaces were measured by x-ray photoelectron spectroscopy (XPS). The peak position XPS spectrum 3d from shifted value metallic to that GaN, indicating formation GaN surface. Formation also confirmed spectra N 1s signals. It found energy up 4keV useful form implanted atoms remained...
We have investigated the terahertz electromagnetic waves from undoped GaAs/n-type GaAs (i-GaAs/n-GaAs) structures with various i-GaAs-layer thicknesses, focusing on relation between sub-picosecond-range carrier-transport processes and terahertz-wave frequency. It is observed that intense monocycle oscillation induced by surge current of photogenerated carriers followed signal coherent longitudinal optical (LO) phonon. The Fourier power spectra waveforms reveal an increase in built-in...
An improved method to fabricate a small lateral double tunnel junction which utilizes focused ion beam (FIB) etching and lift-off techniques is proposed. A layer resist consisting of nitrocellulose germanium layers was used. Narrow grooves with widths comparable or narrower than the FIB diameter were formed in ferromagnetic Ni, Ni/Ni-oxide/Au/Ni-oxide/Ni Al/Al-oxide/Ni/Al-oxide/Al structures fabricated using proposed method. The measured voltage current characteristics latter indicated that...
Formation of hydrogen-free gallium nitride (GaN) thin layers by ion beam direct deposition method under nitrogen ambient was investigated. After a Ga at an energy 100eV irradiated on chip Si(111) wafer gas pressure 2×10−4Torr using tungsten hot filament, the composition and chemical bonding nature deposited materials were investigated x-ray photoelectron spectroscopy (XPS). Although material filament power 250W showed almost metallic nature, XPS spectra 300W very similar to that epitaxially...