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Träfflista för sökning "WFRF:(Song Yuxin 1981) ;hsvcat:1"

Sökning: WFRF:(Song Yuxin 1981) > Naturvetenskap

  • Resultat 1-10 av 19
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1.
  • Fu, Yifeng, 1984, et al. (författare)
  • Templated Growth of Covalently Bonded Three-Dimensional Carbon Nanotube Networks Originated from Graphene
  • 2012
  • Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 24:12, s. 1576-1581
  • Tidskriftsartikel (refereegranskat)abstract
    • A template-assisted method that enables the growth of covalently bonded three-dimensional carbon nanotubes (CNTs) originating from graphene at a large scale is demonstrated. Atomic force microscopy-based mechanical tests show that the covalently bonded CNT structure can effectively distribute external loading throughout the network to improve the mechanical strength of the material.
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2.
  • Charpentier, Sophie, 1983, et al. (författare)
  • Induced unconventional superconductivity on the surface states of Bi2Te3 topological insulator
  • 2017
  • Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723 .- 2041-1723. ; 8:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Topological superconductivity is central to a variety of novel phenomena involving the interplay between topologically ordered phases and broken-symmetry states. The key ingredient is an unconventional order parameter, with an orbital component containing a chiral p(x) + ip(y) wave term. Here we present phase-sensitive measurements, based on the quantum interference in nanoscale Josephson junctions, realized by using Bi2Te3 topological insulator. We demonstrate that the induced superconductivity is unconventional and consistent with a sign-changing order parameter, such as a chiral px + ipy component. The magnetic field pattern of the junctions shows a dip at zero externally applied magnetic field, which is an incontrovertible signature of the simultaneous existence of 0 and pi coupling within the junction, inherent to a non trivial order parameter phase. The nano-textured morphology of the Bi2Te3 flakes, and the dramatic role played by thermal strain are the surprising key factors for the display of an unconventional induced order parameter.
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3.
  • galletti, luca, 1986, et al. (författare)
  • High-Transparency Al/Bi2Te3 Double-Barrier Heterostructures
  • 2017
  • Ingår i: IEEE Transactions on Applied Superconductivity. - 1558-2515 .- 1051-8223. ; 27:4
  • Tidskriftsartikel (refereegranskat)abstract
    • We have fabricated highly transparent Al/Bi2Te3/Al superconductor/normal metal/superconductor double-barrier heterostructures. Transport measurements reveal the presence of multiple Andreev reflections related to two distinct energy gaps that we identify as the induced superconducting gap in the two electrodes. The realization of high-transparency Josephson junctions with topological insulators is an important step towards the study of topological superconductivity and Majorana fermions.
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4.
  • Segercrantz, N., et al. (författare)
  • Defect studies in MBE grown GaSb1-x Bi x layers
  • 2014
  • Ingår i: AIP Conference Proceedings. - : AIP Publishing LLC. - 1551-7616 .- 0094-243X. ; 1583, s. 174-177
  • Konferensbidrag (refereegranskat)abstract
    • Positron annihilation spectroscopy in Doppler broadening mode is used to study epitaxial layers of GaSb 1-x Bi x on undoped GaSb. The samples were grown by Molecular Beam Epitaxy at different temperatures and with different Bi/Sb beam equivalent pressure ratios resulting in Bi concentrations of 0-0.7 %. The results show a relationship between the growth parameters and Doppler broadening parameters. Incorporating Bi into GaSb decreases the vacancy concentration in the epitaxial layers compared to the sample with no Bi in the epitaxial layer.
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5.
  • Song, Yuxin, 1981, et al. (författare)
  • Dilute bismides for near and mid-infrared applications
  • 2013
  • Ingår i: 2013 15th International Conference on Transparent Optical Networks (ICTON). - 2162-7339. - 9781479906826 ; , s. 6602735-
  • Konferensbidrag (refereegranskat)abstract
    • Dilute bismides are a group of emerging materials with unique properties. Incorporation of a small amount of Bi in common III-V host materials results in large band-gap reduction and strong spin-orbit splitting, leading to potential applications in near-infrared (NIR) and mid-infrared (MIR) optoelectronics. Recent progresses on molecular beam epitaxy (MBE) of novel III-Sb-Bi, i.e. GaSbBi and InSbBi thin films from our group are summarised in this paper. Quantum well structures based on GaSbBi and InGaAsBi aiming for the optical communication window were grown and characterized.
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6.
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7.
  • Song, Yuxin, 1981, et al. (författare)
  • Effects of doping and grading slope on surface and structure of metamorphic InGaAs buffers on GaAs substrates
  • 2009
  • Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 106:12, s. 123531-
  • Tidskriftsartikel (refereegranskat)abstract
    • We investigate the effects of doping and grading slope on the surface and structure of linearly alloy graded InGaAs buffers. It is found that the Be doping can improve material properties, resulting in smaller surface roughness and a lower threading dislocation density, while the Si doping has an opposite effect. The effect is strongly dependent on the grading slope. A moderate In grading slope is preferable for the strain relaxation and the minimization of the negative effect of Si doping. Physical mechanisms are proposed to explain the experimental observations. Since doping is essential for many types of optoelectronic devices, these results are valuable for improving the material properties and performance of metamorphic devices.
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8.
  • Song, Yuxin, 1981, et al. (författare)
  • Enhancement of optical quality in metamorphic quantum wells using dilute nitride buffers
  • 2010
  • Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 97:9, s. 091903-
  • Tidskriftsartikel (refereegranskat)abstract
    • Strong enhancement of optical quality in quantum wells by incorporating nitrogen in metamorphic InGaAs buffers grown on GaAs substrates is demonstrated. This has resulted in 3.7 or 5.4 times enhancement of photoluminescence intensity from the metamorphic quantum wells when using dilute nitride superlattice alone or adding nitrogen in a strain compensated GaAs/In0.3Al0.7As superlattice, respectively. This study shows great potentials by incorporating N in metamorphic buffers to further improve the quality of metamorphic optoelectronic devices.
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9.
  • Tångring, Ivar, 1978, et al. (författare)
  • A study of the doping influence on strain relaxation of graded composition InGaAs layers grown by molecular beam epitaxy
  • 2009
  • Ingår i: Journal of Crystal Growth. - 0022-0248. ; 311, s. 1684-
  • Tidskriftsartikel (refereegranskat)abstract
    • We investigate the role of p- and n-type doping in strain relaxation of graded composition InGaAs layers grown by molecular beam epitaxy. It is found that p-type Be-doping can improve material properties, resulting in smaller surface roughness and lower threading dislocation density, while n-type Si-doping has an opposite effect. The effect is strongly dependent on the grading profile, with linear grading showing small differences, while there is a significant difference when an exponential grading is used. Since doping is essential for many types of devices, these results are useful for improving the material properties and performance of metamorphic devices.
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10.
  • Chen, X, et al. (författare)
  • Shallow-terrace-like interface in dilute-bismuth GaSb/AlGaSb single quantum wells evidenced by photoluminescence
  • 2013
  • Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 113:15, s. 153505-153507
  • Tidskriftsartikel (refereegranskat)abstract
    • Photoluminescence (PL) measurements are performed on one GaSb/AlGaSb single-quantum-well (SQW) sample and two dilute-bismuth (Bi) GaSb/AlGaSb SQW samples grown at 360 and 380 °C, at low temperatures and under magnetic fields. Bimodal PL features are identified in the dilute-Bi samples, and to be accompanied by abnormal PL blueshift in the sample grown at 360 °C. The bimodal PL features are found to be from similar origins of band-to-band transition by magneto-PL evolution. Analysis indicates that the phenomenon can be well interpreted by the joint effect of interfacial large-lateral-scale islands and Al/Ga interdiffusion due to Bi incorporation. The interdiffusion introduces about 1-monolayer shrinkage to the effective quantum-well thickness, which is similar to the interfacial islands height, and the both together result in an unusual shallow-terrace-like interface between GaSbBi and AlGaSb. A phenomenological model is established, the Bi content of isoelectronic incorporation and the exciton reduced effective mass are estimated for the GaSbBi sample grown at 380 °C, and a value of about 21 meV/% is suggested for the bandgap bowing rate of GaSbBi. An effective routine is suggested for determining the Bi content and the depth of the shallow-terraces at interface in dilute-Bi SQW structures.
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  • Resultat 1-10 av 19

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