Naoki Fukata

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Magnetic/fluorescent composite materials have become one of the most important tools in the imaging modality in vivo using magnetic resonance imaging (MRI) monitoring and fluorescence optical imaging. We report herein on a simplified procedure to synthesize hybrid nanoparticles (HNPs) that combine silicon and magnetic iron oxides consisting of magnetite(More)
Gaining an understanding the dynamic behaviors of dopant atoms in silicon nanowires (SiNWs) is the key to achieving low-power and high-speed transistor devices using SiNWs. The segregation behavior of boron (B) and phosphorus (P) atoms in B- and P-doped SiNWs during thermal oxidation was closely observed using B local vibrational peaks and Fano broadening(More)
Impurity doping is the most important technique to functionalize semiconductor nanowires. The crucial point is how the states of impurity atoms can be detected. The chemical bonding states and electrical activity of boron (B) and phosphorus (P) atoms in germanium nanowires (GeNWs) are clarified by micro-Raman scattering measurements. The observation of B(More)
We report the influence of the native amorphous SiO(2) shell on the cathodoluminescence emission of 3C-SiC/SiO(2) core/shell nanowires. A shell-induced enhancement of the SiC near-band-edge emission is observed and studied as a function of the silicon dioxide thickness. Since the diameter of the investigated SiC cores rules out any direct bandgap optical(More)
Inorganic/organic hybrid radial heterojunction solar cells that combine vertically-aligned n-type silicon nanowires (SiNWs) with poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS) have great potential for replacing commercial Si solar cells. The chief advantage of such solar cells is that they exhibit higher absorbance for a given(More)
Core-shell nanowires (NWs) composed of silicon (Si) and germanium (Ge) are key structures for realizing high mobility transistor channels, since the site-selective doping and band-offset in core-shell NWs separate the carrier transport region from the impurity doped region, resulting in the suppression of impurity scattering. Four different types of Si/Ge(More)
Deformation and fracture mechanisms of ultrathin Si nanowires (NWs), with diameters of down to ~9 nm, under uniaxial tension and bending were investigated by using in situ transmission electron microscopy and molecular dynamics simulations. It was revealed that the mechanical behavior of Si NWs had been closely related to the wire diameter, loading(More)
We report the first observation of the electronic level scheme in boron (B)- and phosphorus (P)-doped nanowires (NWs). The NWs' morphology dramatically depends on the doping impurity while a few deep electronic levels appear in both kinds of nanowires, independently of the doping type. We demonstrate that the doping impurities induce the same shallow levels(More)
It is demonstrated that boron-doped nanowires have predominantly long-term stable wurtzite phase while the majority of phosphorus-doped ones present diamond phase. A simplified model based on the different solubility of boron and phosphorus in gold is proposed to explain their diverse effectiveness in retaining the wurtzite phase. The wurtzite nanowires(More)
Recrystallization of silicon nanowires (SiNWs) after ion implantation strongly depends on the ion doses and species. Full amorphization by high-dose implantation induces polycrystal structures in SiNWs even after high-temperature annealing, with this tendency more pronounced for heavy ions. Hot-implantation techniques dramatically suppress(More)