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Sökning: WFRF:(Fu Yifeng 1984)

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  • Fu, Yifeng, 1984, et al. (författare)
  • Templated Growth of Covalently Bonded Three-Dimensional Carbon Nanotube Networks Originated from Graphene
  • 2012
  • Ingår i: Advanced Materials. - 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.
  • Fu, Yifeng, 1984, et al. (författare)
  • Thermal Characterization of Low-Dimensional Materials by Resistance Thermometers
  • 2019
  • Ingår i: Materials. - 1996-1944. ; 12:11
  • Forskningsöversikt (refereegranskat)abstract
    • The design, fabrication, and use of a hotspot-producing and temperature-sensing resistance thermometer for evaluating the thermal properties of low-dimensional materials are described in this paper. The materials that are characterized include one-dimensional (1D) carbon nanotubes, and two-dimensional (2D) graphene and boron nitride films. The excellent thermal performance of these materials shows great potential for cooling electronic devices and systems such as in three-dimensional (3D) integrated chip-stacks, power amplifiers, and light-emitting diodes. The thermometers are designed to be serpentine-shaped platinum resistors serving both as hotspots and temperature sensors. By using these thermometers, the thermal performance of the abovementioned emerging low-dimensional materials was evaluated with high accuracy.
  • Fu, Yifeng, 1984, et al. (författare)
  • Thick film patterning by lift-off process using double-coated single photoresists
  • 2012
  • Ingår i: Materials Letters. - 0167-577X. ; 76, s. 117-119
  • Tidskriftsartikel (refereegranskat)abstract
    • A novel method using lift-off process for patterning very thick materials is developed and demonstrated. Unlike conventional lift-off processes, no special lift-off resist is used in this method. Instead, only a double-coated single photoresist is needed. Demonstrations using two commercial photoresists show that good patterning morphology and obvious undercuts as high as 15 mu m are obtained for lift-off, which is very difficult to achieve by existing methods. The application and feasibility of this approach is demonstrated by a carbon nanotube transfer process. This simple and effective method offers wider option to pattern very thick materials in high quality which are in strong demands.
  • Fu, Yifeng, 1984, et al. (författare)
  • Ultrafast Transfer of Metal Enhanced Carbon Nanotubes at Low Temperature for Large Scale Electronics Assembly
  • 2010
  • Ingår i: Advanced Materials. - 0935-9648 .- 1521-4095. ; 22:44, s. 5039-5042
  • Tidskriftsartikel (refereegranskat)abstract
    • An indium-assisted ultrafast carbon nanotube (CNT) transfer method with a yield rate over 90% is described. Metal-coated as-transferred CNT structures exhibit excellent electrical performance that is at least one order of magnitude better than the previously published results. Shear test results show that the adhesion between CNTs and the substrate is greatly improved and excellent flexibility is obtained after the transfer process.
  • Gao, Zhaoli, 1986, et al. (författare)
  • Graphene Heat Spreader for Thermal Management of Hot Spots
  • 2013
  • Ingår i: Proceedings of the IEEE 2013 Electronic Components & Technology Conference. - 0569-5503. ; , s. 2075-2078
  • Konferensbidrag (refereegranskat)abstract
    • Monolayer graphene was fabricated using thermal chemical vapor deposition (TCVD) as heat spreaders in electronic packaging. Platinum (Pt) thermal evaluation chips were utilized to evaluate the thermal performance of the graphene heat spreaders. Temperature of hot spot driven at a heat flux of up to 430W·cm -2 was decreased by about 13 °C with the attaching of the graphene heat spreader. We demonstrate the potentials of using CMOS compatible TCVD process to make graphene as heat spreader for power dissipation needs. © 2013 IEEE.
  • Gao, Zhaoli, et al. (författare)
  • Graphene Heat Spreader for Thermal Management of Hot Spots in Electronic Packaging
  • 2012
  • Ingår i: Proceedings of the 18th Therminic International Workshop on Thermal Investigations of ICs and Systems. ; , s. 217-220
  • Konferensbidrag (refereegranskat)abstract
    • Monolayer graphene was fabricated using thermal CVD for the application of heat spreader in electronic packaging. Platinum (Pt) micro-heater embedded thermal testing chips were utilized to evaluate the thermal performance of the graphene heat spreader. The hot spot temperature was decreased by about 5 degrees C at a heat flux of up to 800W/cm2. It is possible to further improve the thermal performance of graphene heat spreader by optimizing the synthesis parameters and transfer process.
  • han, Hao xue, et al. (författare)
  • Enhanced Heat Spreader Based on Few-Layer Graphene Intercalated With Silane-Functionalization Molecules
  • 2014
  • Ingår i: IEEE 20th International Workshop on Thermal Investigation of ICs and Systems (Therminic). Greenwich, London, United Kingdom, 24-26 September 2014. ; , s. 1-4
  • Konferensbidrag (refereegranskat)abstract
    • We studied the heat-spreading enhancement of supported few-layer graphene by inserting silane-functionalization molecules between graphene sheets. We calculated the overall thermal resistance of graphene-substrate interface and the in-plane thermal conductivity of graphene sheets by equilibrium molecular dynamics simulations. We probed the spectral phonon transmission coefficient by non-equilibrium Green's function to characterize the local heat conduction through the interface. Our results show that the overal thermal resistance between the substrate graphene and the upper two-layer graphene underwent a three-fold increase by the presence of the molecules, while the local heat conduction from the hot spot to the graphene sheets through the molecules was largely intensified. Furthermore, the in-plane thermal conductivity of the few-layer graphene increased by 60% compared with the supported graphene non-bonded to the substrate through the molecules. This increase is attributed to the refrained cross-plane phonon scattering which in turn reinforces the in-plane heat conduction of the few-layer graphene. In summary, we proved that by inserting silane-functionalization molecules, the few-layer graphene becomes an ideal candidate for heat spreading by guiding heat more efficiently away from the heat source.
  • Han, H. X., et al. (författare)
  • Functionalization mediates heat transport in graphene nanoflakes
  • 2016
  • Ingår i: Nature Communications. - 2041-1723. ; 7
  • Tidskriftsartikel (refereegranskat)abstract
    • The high thermal conductivity of graphene and few-layer graphene undergoes severe degradations through contact with the substrate. Here we show experimentally that the thermal management of a micro heater is substantially improved by introducing alternative heat-escaping channels into a graphene-based film bonded to functionalized graphene oxide through amino-silane molecules. Using a resistance temperature probe for in situ monitoring we demonstrate that the hotspot temperature was lowered by similar to 28 degrees C for a chip operating at 1,300 Wcm(-2). Thermal resistance probed by pulsed photothermal reflectance measurements demonstrated an improved thermal coupling due to functionalization on the graphene-graphene oxide interface. Three functionalization molecules manifest distinct interfacial thermal transport behaviour, corroborating our atomistic calculations in unveiling the role of molecular chain length and functional groups. Molecular dynamics simulations reveal that the functionalization constrains the cross-plane phonon scattering, which in turn enhances in-plane heat conduction of the bonded graphene film by recovering the long flexural phonon lifetime.
  • Hansson, Josef, 1991, et al. (författare)
  • Effects of high temperature treatment of carbon nanotube arrays on graphite: increased crystallinity, anchoring and inter-tube bonding
  • 2020
  • Ingår i: Nanotechnology. - : Institute of Physics Publishing (IOPP). - 1361-6528 .- 0957-4484. ; 31:45
  • Tidskriftsartikel (refereegranskat)abstract
    • Thermal treatment of carbon nanotubes (CNTs) can significantly improve their mechanical, electrical and thermal properties due to reduced defects and increased crystallinity. In this work we investigate the effect of annealing at 3000 degrees C of vertically aligned CNT arrays synthesized by chemical vapor deposition (CVD) on graphite. Raman measurements show a drastically reduced amount of defects and, together with transmission electron microscope (TEM) diffraction measurements, an increased average crystallite size of around 50%, which corresponds to a 124% increase in Young's modulus. We also find a tendency for CNTs to bond to each other with van der Waals (vdW) forces, which causes individual CNTs to closely align with each other. This bonding causes a densification effect on the entire CNT array, which appears at temperatures >1000 degrees C. The densification onset temperature corresponds to the thermal decomposition of oxygen containing functional groups, which otherwise prevents close enough contact for vdW bonding. Finally, the remaining CVD catalyst on the bottom of the CNT array is evaporated during annealing, enabling direct anchoring of the CNTs to the underlying graphite substrate.
  • Hu, Zhili, 1983, et al. (författare)
  • Detecting single molecules inside a carbon nanotube to control molecular sequences using inertia trapping phenomenon
  • 2012
  • Ingår i: Applied Physics Letters. - 0003-6951 .- 1077-3118. ; 101:13, s. Art. no. 133105-
  • Tidskriftsartikel (refereegranskat)abstract
    • Here we show the detection of single gas molecules inside a carbon nanotube based on the change inresonance frequency and amplitude associated with the inertia trapping phenomenon. As its directimplication, a method for controlling the sequence of small molecule is then proposed to realize theconcept of manoeuvring of matter atom by atom in one dimension. The detection as well as theimplication is demonstrated numerically with the molecular dynamics method. It is theoreticallyassessed that it is possible for a physical model to be fabricated in the very near future.
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