SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "WFRF:(Murayama Akihiro) "

Sökning: WFRF:(Murayama Akihiro)

  • Resultat 1-6 av 6
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Chen, Yafeng, et al. (författare)
  • Temperature-dependent radiative and non-radiative dynamics of photo-excited carriers in extremely high-density and small InGaN nanodisks fabricated by neutral-beam etching using bio-nano-templates
  • 2018
  • Ingår i: Journal of Applied Physics. - : AMER INST PHYSICS. - 0021-8979 .- 1089-7550. ; 123:20
  • Tidskriftsartikel (refereegranskat)abstract
    • Temperature-dependent radiative and non-radiative dynamics of photoexcited carriers were studied in In0.3Ga0.7N nanodisks (NDs) fabricated from quantum wells (QWs) by neutral-beam etching using bio-nano-templates. The NDs had a diameter of 5 nm, a thickness of 2 and 3 nm, and a sheet density of 2 x 10(11) cm(-2). The radiative decay time, reflecting the displacement between the electron and hole wavefunctions, is about 0.2 ns; this value is almost constant as a function of temperature in the NDs and not dependent on their thickness. We observed non-exponential decay curves of photoluminescence (PL) in the NDs, particularly at temperatures above 150 K. The thermal activation energies of PL quenching in the NDs are revealed to be about 110 meV, corresponding to the barrier heights of the valence bands in the disks. Therefore, hole escape is deemed responsible for the PL quenching, while thermal activation energies of 12 meV due to the trapping of carriers by defects were dominant in the mother QWs. The above-mentioned non-exponential PL decay curves can be attributed to variations in the rate of hole escape in the NDs because of fluctuations in the valence-band barrier height, which, in turn, is possibly due to compositional fluctuations in the QWs. We found that non-radiative trapping, characteristic of the original QW, also exists in about 1% of the NDs in a form that is not masked by other newly formable defects. Therefore, we suggest that additional defect formation is not significant during our ND fabrication process. Published by AIP Publishing.
  •  
2.
  • Higo, Akio, et al. (författare)
  • Optical Study of Sub-10 nm In0.3Ga0.7N Quantum Nanodisks in GaN Nanopillars
  • 2017
  • Ingår i: ACS Photonics. - : American Chemical Society (ACS). - 2330-4022. ; 4:7, s. 1851-1857
  • Tidskriftsartikel (refereegranskat)abstract
    • We have demonstrated the fabrication of homogeneously distributed In0.3Ga0.7N/GaN quantum nanodisks (QNDs) with a high density and average diameter of 10 nm or less in 30-nm-high nanopillars. The scalable top-down nanofabrication process used biotemplates that were spin-coated on an In0.3Ga0.7N/GaN single quantum well (SQW) followed by low-damage dry etching on ferritins with 7 nm diameter iron cores. The photoluminescence measurements at 70 K showed a blue shift of quantum energy of 420 meV from the In0.3Ga0.7N/GaN SQW to the QND. The internal quantum efficiency of the In0.3Ga0.7N/GaN QND was 100 times that of the SQW. A significant reduction in the quantum-confined Stark effect in the QND structure was observed, which concurred with the numerical simulation using a 3D Schrödinger equation. These results pave the way for the fabrication of large-scale III–N quantum devices using nanoprocessing, which is vital for optoelectronic communication devices.
  •  
3.
  • Huang, Yuqing, et al. (författare)
  • Room-temperature electron spin polarization exceeding 90% in an opto-spintronic semiconductor nanostructure via remote spin filtering
  • 2021
  • Ingår i: Nature Photonics. - : NATURE RESEARCH. - 1749-4885 .- 1749-4893. ; 15, s. 475-482
  • Tidskriftsartikel (refereegranskat)abstract
    • An exclusive advantage of semiconductor spintronics is its potential for opto-spintronics, which will allow integration of spin-based information processing/storage with photon-based information transfer/communications. Unfortunately, progress has so far been severely hampered by the failure to generate nearly fully spin-polarized charge carriers in semiconductors at room temperature. Here we demonstrate successful generation of conduction electron spin polarization exceeding 90% at room temperature without a magnetic field in a non-magnetic all-semiconductor nanostructure, which remains high even up to 110 degrees C. This is accomplished by remote spin filtering of InAs quantum-dot electrons via an adjacent tunnelling-coupled GaNAs spin filter. We further show that the quantum-dot electron spin can be remotely manipulated by spin control in the adjacent spin filter, paving the way for remote spin encoding and writing of quantum memory as well as for remote spin control of spin-photon interfaces. This work demonstrates the feasibility to implement opto-spintronic functionality in common semiconductor nanostructures. An electron spin polarization of 90% is achieved in a non-magnetic nanostructure at room temperature without magnetic field. This is accomplished by remote spin filtering of InAs quantum-dot electrons via an adjacent tunnelling-coupled GaNAs spin filter.
  •  
4.
  • Kodama, Tomonobu, et al. (författare)
  • Identification of Metal-Binding Peptides and Their Conjugation onto Nanoparticles of Superparamagnetic Iron Oxides and Liposomes
  • 2020
  • Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 12:22, s. 24623-24634
  • Tidskriftsartikel (refereegranskat)abstract
    • Metallic materials are used for clinical medical devices such as vascular stents and coils to treat both ischemic and hemorrhagic vascular diseases. An antiplatelet drug is required to avoid thromboembolic complication until metallic surface is covered with a neo-endothelial cell layer. It is important to identify endothelial cell coverage on the metallic surface. However, it is difficult since there are no selective ligands. Here, we used the phage display method to identify peptide ligands that had high affinity for the metallic surface of Ni-Ti stents, Pt-W coils, and Co-Cr stents. The binding assay using fluorescence labeling revealed that several synthetic peptides could bind onto those surfaces. We also chose some oligopeptides for the conjugation onto superparamagnetic iron oxide (SPIO) nanoparticles and liposome-encapsulating SPIO nanoparticles and studied their ability to bind to the stent and coils. By SEM and fluorophotometry, we found that those modified SPIOs and liposomes were selectively bound onto those surfaces. In addition, both treated stents and coils could be detected by magnetic resonance imaging due to the magnetic artifact through the SPIOs and liposomes that were immobilized onto the surface. Thus, we identified metal-binding peptides which may enable to stop antiplatelet therapy after vascular stenting or coiling.
  •  
5.
  • Nakama, Kaito, et al. (författare)
  • GaAs/GaInNAs core-multishell nanowires with a triple quantum-well structure emitting in the telecommunication range
  • 2023
  • Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 123:8
  • Tidskriftsartikel (refereegranskat)abstract
    • Semiconducting nanowires (NWs) fabricated from III-V materials have gained significant attention for their application in advanced optoelectronic devices. Here, the growth of GaAs/GaInNAs/GaAs core-multishell NWs with a triple quantum-well structure, having about 2% N and 20% In, is reported. The NWs are grown via selective area plasma-assisted molecular beam epitaxy on patterned Si(111) substrates with SiO2 mask holes. The nucleation and growth of the GaAs nanowires core are carried out by Ga-induced vapor-liquid-solid growth at the open holes. Finely controlled, vertically aligned, regular core-multishell NWs with uniform wire length and diameter are obtained with a 96% yield and targeted nitrogen concentrations of 0%, 2%, and 3%. The GaInNAs NWs exhibit a spectral red shift relative to the GaAs NWs peak. Their emission wavelength increases with the N content reaching up to 1.26 mu m, which makes them a promising tool in telecommunication light sources.
  •  
6.
  • Park, Jiho, et al. (författare)
  • Spin-Conserving Tunneling of Excitons in Diluted Magnetic Semiconductor Double Quantum Wells
  • 2008
  • Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 47, s. 3533-3536
  • Tidskriftsartikel (refereegranskat)abstract
    • Spin polarization in carrier tunneling was studied in double quantum wells by the polarized photoluminescence-excitation spectroscopy. The double quantum wells consist of a diluted magnetic quantum well of Zn0.77Cd0.15Mn0.08Se and a nonmagnetic quantum well of Zn0.82Cd0.18Se. Efficient spin-conserving tunneling of an exciton as an entity was observed from the nonmagnetic quantum well to the magnetic well. The spin-reversing tunneling was suppressed by two orders of magnitude in high magnetic field. The spin-conserving tunneling time was determined as 20 ps by time resolved photoluminescence measurement.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-6 av 6

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy