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oe1(光电查) - 科学论文

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出版时间
  • 2018
研究主题
  • gate oxide integrity
  • avalanche ruggedness
  • SiC MOSFET
  • bias temperature instability
应用领域
  • Electronic Science and Technology
机构单位
189 条数据
?? 中文（中国） ▾

  • Protons and carbon ions acceleration in the target-normal-sheath-acceleration regime using low-contrast <i>fs</i> laser and metal-graphene targets

    摘要： fs pulsed lasers at an intensity of the order of 1018 W/cm2, with a contrast of 10?5, were employed to irradiate thin foils to study the target-normal-sheath-acceleration (TNSA) regime. The forward ion acceleration was investigated using 1/11 μm thickness foils composed of a metallic sheet on which a thin reduced graphene oxide film with 10 nm thickness was deposited by single or both faces. The forward-accelerated ions were detected using SiC semiconductors connected in time-of-flight configuration. The use of intense and long pre-pulse generating the low contrast does not permit to accelerate protons above 1 MeV because it produces a pre-plasma destroying the foil, and the successive main laser pulse interacts with the expanding plasma and not with the overdense solid surface. Experimental results demonstrated that the maximum proton energies of about 700 keV and of 4.2 MeV carbon ions and higher were obtained under the condition of the optimal acceleration procedure. The measurements of ion energy and charge states confirm that the acceleration per charge state is measurable from the proton energy, confirming the Coulomb–Boltzmann-shifted theoretical model. However, heavy ions cannot be accelerated due to their mass and low velocity, which does not permit them to be subjected to the fast and high developed electric field driving the light-ion acceleration. The ion acceleration can be optimized based on the laser focal positioning and on the foil thickness, composition, and structure, as it will be presented and discussed.

    关键词： TNSA,laser-generated plasma,SiC detector,ion acceleration in plasma

    更新于2025-09-11 14:15:04

  • Nanoforest of 3C–SiC/graphene by laser chemical vapor deposition with high electrochemical performance

    摘要： Nanoforests of 3C–SiC/graphene films are prepared by laser chemical vapor deposition (LCVD). The effectiveness of nanoforest-like 3C–SiC/graphene film as electrode materials for supercapacitors has been investigated by cyclic voltammetry and galvanostatic charge-discharge tests in 0.5 M H2SO4 solution. The specific capacitance is 8.533 mF/cm2 at a current density of 20 μA/cm2, which is 15 times higher than of previous reports of composited 3C–SiC/graphene films. The electrode exhibits good rate capability and cycling stability with 90.5% capacitance retention after 10000 cycles. The nanoforest-like 3C–SiC/graphene thick film shows a 3D porous structure with exposed graphene conductive network contributing to the greatly enhanced electrochemical performance in an environmentally aqueous electrolyte. These nanoforest-like 3C–SiC/graphene films can be promising for electrochemical energy storage applications.

    关键词： Nanoforest,LCVD,3C–SiC films,Graphene,Electrochemical performance

    更新于2025-09-11 14:15:04

  • Wideband Transition for Increased-Height Empty Substrate Integrated Waveguide

    摘要： Recently, Empty Substrate Integrated Waveguide (ESIW) technology was proposed for embedding empty waveguides into planar substrates in order to improve their performance. A low-loss and narrow-band transition from microstrip to an increased height ESIW with 4 layers was presented in a previous work, and used to implement a very high-quality factor bandpass filter at Q-band. With such a narrow-band transition, based on a quarter-wavelength transformer, a very narrow-band filter response with resonators having a quality factor of 1000 was achieved. In this paper, in order to overcome the narrow-band and the 4-layers output restrictions, and extend the practical use of such increased height ESIWs beyond narrow-band filters, we present a novel wideband transition from microstrip to an increased height ESIW with an arbitrary number of layers. A full suite of wideband transitions to increased height ESIWs, built with different number of substrate layers ranging from 3 to 8, has been designed in this work to operate at Ka-band, though they can be easily transferred to other bands if the dimensions of the transition are properly scaled. To illustrate this, the original Ka-band transitions have been mapped to Ku-band, with excellent results. In order to test the proposed design method, a prototype of a 4-layer structure has been fabricated at Ka-band, achieving a good performance in the whole useful bandwidth of the ESIW.

    关键词： Empty substrate integrated waveguide,multilayer,SIW,substrate integrated waveguide,substrate integrated circuit,microstrip transition,high quality factor,SIC,ESIW

    更新于2025-09-11 14:15:04

  • [IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - SiC-SiO <sub/>2</sub> MEMS-DBR Based Widely Tunable Optical Filters Around 1550 nm with Narrow FWHM

    摘要： Ever growing optical data transmission networks and miniaturization of spectroscopic equipment demand for small, energy efficient and mass-produced optical components. Here we present distributed Bragg reflector (DBR) mirror based widely tunable optical Fabry-Perot filters comprising a novel material combination namely, silicon carbide (SiC) and silicon dioxide (SiO2) layers with refractive indices of 2.46 and 1.45, respectively. The resulting refractive index step of 1, provides high reflectivities (>99.5 %) with wide stopbands of more than 300 nm. Hence, large wavelength tuning range and a narrow full width at half maximum (FWHM) filtered signals can be produced. Structuring the dielectric layers by surface micromachining creates a free standing movable mirror supported by four beams. Due to inherent stress created during low-temperature plasma enhanced chemical vapor depositions (PECVD) we obtain a tunable stable plane concave resonator. In the end the cross section of a filter shows a fixed bottom DBR deposited on a silicon substrate, a tunable airgap and an electrothermally actuated top MEMS DBR with a gold electrode for heating current IMEMS. On the substrate backside where the filtered signal is exiting an anti-reflection coating is deposited.

    关键词： tunable optical filters,SiC-SiO2 MEMS-DBR,PECVD,Fabry-Perot filters,surface micromachining

    更新于2025-09-11 14:15:04

  • Porous SiC-mullite ceramics with high flexural strength and gas permeability prepared from photovoltaic silicon waste

    摘要： In this paper, porous SiC-mullite ceramics (PSMCs) with high ?exural strength and gas permeability were prepared with various mass fractions of MoO3 and Al2O3. Higher performance was achieved at low sintering temperatures and the problem of large amounts of cristobalite phase in the PSMCs was solved. The results show that 4 wt% MoO3 is optimal for the growth of mullite rods at a sintering temperature of 850 °C. Porosity was e?ectively controlled by the formation of interlocking structure and mechanical strength was not obviously a?ected. Therefore, the optimal content of Al2O3 was 25 wt% in samples prepared at 850–1200 °C, as the ?exural strength was generally higher than that in samples with other Al2O3 contents. The highest ?exural strength of 66.02 MPa was achieved at an open porosity of 45.4%, gas permeability of 2.32 × 10?13 m2, and permeance of 4.62 × 10?5 mol m?2 s?1 Pa?1 in samples sintered at 1000 °C. This work is of signi?cance for the industrial preparation of PSMCs from photovoltaic silicon waste.

    关键词： MoO3,Photovoltaic solid waste,Porous SiC ceramic,Mullite

    更新于2025-09-11 14:15:04

  • Freedom of Frequency: How the Quest for In-Band Full-Duplex Led to a Breakthrough in Filter Design

    摘要： Wireless self-interference cancellation (SIC) was developed at Stanford University [1], [2] (and spun out as Kumu Networks) to double the spectral efficiency of radio links. SIC enables radios to transmit and receive on the same channel at the same time by canceling out the roar of the local transmitter to hear the whisper of the distant signal.

    关键词： radio links,full duplex,Self-interference cancellation,SIC,spectral efficiency

    更新于2025-09-11 14:15:04

  • Femtosecond-laser-ablation induced transformations in the structure and surface properties of diamond-like nanocomposite films

    摘要： Femtosecond laser ablation processing is applied for surface modification and micropatterning of diamond-like nanocomposite (DLN) films (a-C:H:Si:O films). Using a visible femtosecond laser (wavelength 515 nm, pulse duration 320 fs), microgroove patterns have been fabricated on the DLN films, aimed at further studies of their properties. The studies were focused on (i) structural transformations in the surface layers using Raman spectroscopy and transmission electron microscopy (TEM), (ii) wettability of laser-patterned films, and (iii) nano/microscale friction properties of laser-patterned DLN films using lateral force microscopy. Raman spectroscopy and TEM data showed characteristic features of the surface graphitization during ultrashort-pulse ablation. High resolution TEM study of the microgrooves revealed the formation of cubic SiC nanocrystals (4–8 nm size) on the laser-ablated surface. The water contact angle measurements showed anisotropic wetting behavior of the grooved surfaces (the contact angle was different in the directions parallel and perpendicular to microgrooves), depending on the groove depth (aspect ratio). Lateral force microscopy examination (with micro-sized Si tips) showed that the laser-patterned regions exhibited low friction properties compared to the original surface. The obtained results demonstrate that femtosecond laser processing is an effective technique to generate new properties of hard DLN coatings at the micro and macroscale.

    关键词： Diamond-like nanocomposite films,Femtosecond laser ablation,Micropatterning,SiC nanocrystals,Graphitization,Wettability

    更新于2025-09-11 14:15:04

  • Overview of Recent Progress of Semiconductor Power Devices based on Wide Bandgap Materials

    摘要： Wide bandgap materials, which have shown superior material properties, such as better thermal conductivity and excellent electric performance, have aroused wide concern from scientists and engineers. Currently, research towards semiconductor power devices based on wide bandgap materials has made great achievements. The new developed WBG (wide bandgap) power devices, such as 1200V Direct-Driven SiC JFET power switch and highly reliable GaN MOS HFET displayed better performances and advantages, comparing to traditional Si based power devices. These power devices have been widely used in variety of applications with its successful commercialization, which convincingly proved their reliability and effectiveness. The usage of WBG power devices greatly improved the circuit performance, contributed to the evolve of the new generation electric products. In this paper, we mainly focus on introducing recent progresses and research results of several type of power devices based on WBG materials, including GaN, IGBT, JFET, MOSFET, rectifiers and their SiC counterparts. Their characteristics, performances and relevant applications will be discussed and compared respectively. Then, some deficiency and limits of these devices, as well as solutions of these defects will be illustrated. Finally, future developments and prospects of WBG power devices will be analyzed.

    关键词： rectifiers,GaN,IGBT,MOSFET,wide bandgap materials,SiC,JFET,semiconductor power devices

    更新于2025-09-11 14:15:04

  • -SiC

    摘要： The ?ne-structure splitting in zero magnetic ?eld allows one to access the coherent control and manipulation of polarized spin states. Here the zero-?eld splitting (ZFS) of the S = 3/2 silicon vacancy-related centers in 6H-SiC is explored by means of electron paramagnetic resonance and electron nuclear double resonance techniques, combined with ?rst-principle calculations. We show that the centers not only possess signi?cantly different absolute values of ZFS, but they also differ in their sign. This diversity is rationalized by a ?attened/elongated character of their spin-density distribution, potentially alters spin-photon entanglement, and suggests these centers for qubits in the upcoming technology of quantum communication and quantum-information processing.

    关键词： quantum-information processing,electron paramagnetic resonance,electron nuclear double resonance,zero-?eld splitting,silicon vacancies,6H-SiC,quantum communication

    更新于2025-09-11 14:15:04

  • Magnetic Field Effect of Near-Field Radiative Heat Transfer for SiC Nanowires/Plates

    摘要： The SiC micro/nano-scale structure has advantages for enhancing nonreciprocal absorptance for photovoltaic use due to the magneto optical effect. In this work, we demonstrate the near-?eld radiative transfer between two aligned SiC nanowires/plates under different magnetic ?eld intensities, in which Lorentz-Drude equations of the dielectric constant tensor are proposed to describe the dielectric constant as a magnetic ?eld applied on the SiC structure. The magnetic ?eld strength is quali?ed in this study. Using local effective medium theory and the ?uctuation-dissipation theorem, we evaluate the near-?eld radiation between SiC nanowires with different ?lling ratios and gap distances under an external magnetic ?eld. Compared to the near-?eld heat ?ux between two SiC plates, the one between SiC nanowires can be enhanced with magnetic ?eld intensity, a high ?lling ratio, and a small gap distance. The electric ?eld intensity is also presented for understanding light coupling, propagation, and absorption nature of SiC grating under variable incidence angles and magnetic ?eld strengths. This relative study is useful for thermal radiative design in optical instruments.

    关键词： near-?eld radiation,SiC nanowires,magnetic ?eld effect

    更新于2025-09-11 14:12:44