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Träfflista för sökning "WFRF:(Sun Jie 1977) "

Sökning: WFRF:(Sun Jie 1977)

  • Resultat 1-10 av 63
  • [1]234567Nästa
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1.
  • Zhang, Guobin, et al. (författare)
  • Thermal Analysis of AlGaN/GaN High-Electron-Mobility Transistors with Graphene
  • 2018
  • Ingår i: Journal of Nanoscience and Nanotechnology. - : American Scientific Publishers. - 1533-4880 .- 1533-4899. ; 18:11, s. 7578-7583
  • Tidskriftsartikel (refereegranskat)abstract
    • A thermal analysis of AlGaN/GaN high electron mobility transistors (HEMTs) with Graphene is investigated using Silvaco and Finite Element Method. Two thermal management solutions are adopted; first of all, graphene is used as dissipation material between SiC substrate and GaN buffer layer to reduce thermal boundary resistance of the device. At the same time, graphene is also used as a thermal spread material on the top of the source contacts to reduce thermal resistance of the device. The thermal analysis results show that the temperature rise of device adopting graphene decreases by 46.5% in transistors operating at 13.86 W/mm. Meanwhile, the thermal resistance of GaN HEMTs with graphene is 6.8 K/W, which is much lower than the device without graphene, which is 18.5 K/W. The thermal management solutions are useful for integration of large-scale graphene into practical devices for effective heat spreading in AlGaN/GaN HEMT.
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2.
  • ANDERSSON, MICHAEL, 1988, et al. (författare)
  • Microwave characterization of Ti/Au-graphene contacts
  • 2013
  • Ingår i: Applied Physics Letters. - 0003-6951 .- 1077-3118. ; 103:17, s. 173111-
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper, we report on a microwave characterization of the interface between Ti/Au contacts and chemical vapor deposition graphene using structures of Corbino geometry, with primary focus on extracting and modeling the capacitance associated with the contact region. It is found that with the current contact resistivity, ρc∼10^−6 Ωcm2, the contact capacitance, on the order Cc∼1 μF/cm2, has a negligible effect on microwave transmission through the contact below ∼100 GHz. Finally, a parallel plate capacitance model for the contact is presented.
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3.
  • ANDERSSON, MICHAEL, 1988, et al. (författare)
  • Towards Graphene Electrodes for High Performance Acoustic Resonators
  • 2013
  • Ingår i: WOCSDICE. ; , s. 99-100
  • Konferensbidrag (refereegranskat)abstract
    • The tunable FBAR is a promising building block for versatile microwave systems. Utilizing graphene electrodes promises higher tunability and frequency. Increased parasitic resistance may hamper the Q-factor of the resonator. This paper reports the initiated study of graphene and contacts at DC and microwave frequencies for optimization of these parameters leading to graphene FBARs.
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4.
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5.
  • Buron, J.D., et al. (författare)
  • Correlation between THz AC and micro-four-point-probe DC conductivity mapping of graphene sheets
  • 2012
  • Ingår i: Laser and Tera-Hertz Science and Technology, LTST 2012; Wuhan, China; 1 November 2012 through 2 November 2012.
  • Konferensbidrag (refereegranskat)abstract
    • We present quantitative correlation mapping of the sheet conductance of large areas of graphene. Terahertz time-domain spectroscopy (THz-TDS) maps the nanoscale conductance averaged over the beam spot size whereas micro four-point probe (M4PP) maps the micro-scale conductance.
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6.
  • Buron, J. D., et al. (författare)
  • Graphene Conductance Uniformity Mapping
  • 2012
  • Ingår i: Nano Letters. - 1530-6992 .- 1530-6984. ; 12:10, s. 5074-5081
  • Tidskriftsartikel (refereegranskat)abstract
    • We demonstrate a combination of micro four-point probe (M4PP) and non-contact terahertz time-domain spectroscopy (THz-TDS) measurements for centimeter scale quantitative mapping of the sheet conductance of large area chemical vapor deposited graphene films. Dual configuration M4PP measurements, demonstrated on graphene for the first time, provide valuable statistical insight into the influence of microscale defects on the conductance, while THz-TDS has potential as a fast, non-contact metrology method for mapping of the spatially averaged nanoscopic conductance on wafer-scale graphene with scan times of less than a minute for a 4-in. wafer. The combination of M4PP and THz-TDS conductance measurements, supported by micro Raman spectroscopy and optical imaging, reveals that the film is electrically continuous on the nanoscopic scale with microscopic defects likely originating from the transfer process, dominating the microscale conductance of the investigated graphene film.
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7.
  • Dong, Y. B., et al. (författare)
  • High Light Extraction Efficiency AlGaInP LEDs With Proton Implanted Current Blocking Layer
  • 2016
  • Ingår i: IEEE Electron Device Letters. - 0741-3106. ; 37:10, s. 1303-1306
  • Tidskriftsartikel (refereegranskat)abstract
    • Improving light extraction efficiency is the key issue for light-emitting diodes (LEDs). Nowadays, a vertical structure design dominates LEDs. However, the light from the active region just below the p-electrode is severely blocked by the metal contact. In this letter, we use proton implantation with a depth all the way to the active region to turn the part beneath the p-pad insulating, which constitutes the most-effective-ever current blocking method. Earlier particle implantation studies never reached the device active region. Our experimental results show that the H+-implanted LEDs improve the light output power by 75% compared with non-implanted counterparts and the light intensity increases by 64.48%. By virtue of indium tin oxide current spreading film, the increase in working voltage is negligible. Analyzing the reverse leakage current, the side effect associated with the implantation is limited to an acceptable range. Numerical simulation is performed to support the experiment. Our results represent a new and simple method for solving the light blocking problem in vertical LEDs, without introducing the seemingly existing severe implantation damage to the device structure.
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8.
  • Dong, Y. B., et al. (författare)
  • The growth of graphene on Ni–Cu alloy thin films at a low temperature and its carbon diffusion mechanism
  • 2019
  • Ingår i: Nanomaterials. - : MDPI. - 2079-4991. ; 9:11
  • Tidskriftsartikel (refereegranskat)abstract
    • Carbon solid solubility in metals is an important factor affecting uniform graphene growth by chemical vapor deposition (CVD) at high temperatures. At low temperatures, however, it was found that the carbon diffusion rate (CDR) on the metal catalyst surface has a greater impact on the number and uniformity of graphene layers compared with that of the carbon solid solubility. The CDR decreases rapidly with decreasing temperatures, resulting in inhomogeneous and multilayer graphene. In the present work, a Ni–Cu alloy sacrificial layer was used as the catalyst based on the following properties. Cu was selected to increase the CDR, while Ni was used to provide high catalytic activity. By plasma-enhanced CVD, graphene was grown on the surface of Ni–Cu alloy under low pressure using methane as the carbon source. The optimal composition of the Ni–Cu alloy, 1:2, was selected through experiments. In addition, the plasma power was optimized to improve the graphene quality. On the basis of the parameter optimization, together with our previously-reported, in-situ, sacrificial metal-layer etching technique, relatively homogeneous wafer-size patterned graphene was obtained directly on a 2-inch SiO2 /Si substrate at a low temperature (~600◦ C).
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9.
  • Dong, Y. B., et al. (författare)
  • Transfer-free, lithography-free, and micrometer-precision patterning of CVD graphene on SiO 2 toward all-carbon electronics
  • 2018
  • Ingår i: APL Materials. - 2166-532X. ; 6:2
  • Tidskriftsartikel (refereegranskat)abstract
    • A method of producing large area continuous graphene directly on SiO 2 by chemical vapor deposition is systematically developed. Cu thin film catalysts are sputtered onto the SiO 2 and pre-patterned. During graphene deposition, high temperature induces evaporation and balling of the Cu, and the graphene "lands onto" SiO 2 . Due to the high heating and growth rate, continuous graphene is largely completed before the Cu evaporation and balling. 60 nm is identified as the optimal thickness of the Cu for a successful graphene growth and μm-large feature size in the graphene. An all-carbon device is demonstrated based on this technique.
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10.
  • Dong, Yibo, et al. (författare)
  • In Situ Growth of CVD Graphene Directly on Dielectric Surface toward Application
  • 2020
  • Ingår i: ACS APPLIED ELECTRONIC MATERIALS. - : American Chemical Society (ACS). - 2637-6113. ; 2:1, s. 238-246
  • Tidskriftsartikel (refereegranskat)abstract
    • A technique for the in situ growth of patterned graphene by CVD has been achieved directly on insulating substrates at 800 degrees C. The graphene growth is catalyzed by a Ni-Cu alloy sacrificial layer, which integrates many advantages such as being lithography-free, and almost wrinkle-free, with a high repeatability and rapid growth. The etching method of the metal sacrificial layer is the core of this technique, and the mechanism is analyzed. Graphene has been found to play an important role in accelerating etching speeds. The Ni-Cu alloy exhibits a high catalytic activity, and thus, high-quality graphene can be obtained at a lower temperature. Moreover, the Ni-Cu layer accommodates a limited amount of carbon atoms, which ensures a high monolayer ratio of the graphene. The carbon solid solubility of the alloy is calculated theoretically and used to explain the experimental findings. The method is compatible with the current semiconductor process and is conducive to the industrialization of graphene devices.
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