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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
  • thin-film transistors
  • N2O plasma treatment.
  • amorphous InGaZnO
  • gate-bias stress
  • stability
应用领域
  • Electronic Science and Technology
机构单位
  • Peking University
175 条数据
?? 中文（中国） ▾

  • Preparation of Fe-Co-B-Si-Nb bulk metallic glasses by laser powder bed fusion: Microstructure and properties

    摘要： In this work, laser powder bed fusion (LPBF) was employed for the preparation of {(Fe0.6Co0.4)0.75B0.2Si0.05}96Nb4 bulk metallic glasses (BMGs). Microstructural evolution, thermal stability and mechanical properties of LPBF-processed samples using different laser power and scanning speed were systematically investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron probe microscopy analysis (EPMA), electron backscatter diffraction (EBSD), differential scanning calorimetry (DSC) and nanoindentation. The results show that low area energy input facilitates the formation of Fe-Co-B-Si-Nb BMGs with a large amorphous fraction. LPBF-processed sample with an area energy density of 1.25 J/mm2 (at a laser power of 60 W and a scanning speed of 600 mm/s) exhibits a nearly fully glassy microstructure with an amorphous fraction of approximately 99%, meanwhile identical characteristic properties of LPBF-processed samples are correlated with the processing parameters during LPBF. This work demonstrates that LPBF is a promising method to prepare fully amorphous Fe-Co-B-Si-Nb BMGs. The results provide key insights for the fabrication of BMGs and BMGs composites with the desired microstructure possessing almost and properties by additive manufacturing.

    关键词： Bulk metallic glasses,Laser powder bed fusion,Amorphous fraction,Crystallization,Microstructure,Nanoindentation

    更新于2025-09-23 15:19:57

  • Optical and Structural Phenomena at Multipulse Interference Femtosecond Laser Fabrication of Metasurfaces on a Thin Film of Amorphous Silicon

    摘要： The formation of hexagonal microarrays of nanoholes (metasurfaces) in a 50-nm hydrogenated amorphous silicon film by means of three-beam interference of femtosecond laser pulses of the visible range (wavelength 515 nm) is studied experimentally with various exposures of the film. Characterization of arrays by scanning electron and optical microscopy, as well as optical transmission and reflection microspectroscopy, shows that an increase in the number of fixed energy laser pulses leads to a gradual evaporative formation of nanoholes in the film and, overall, the metasurface. Raman microspectroscopy reveals a simultaneous growth of the volume content of the crystal phase.

    关键词： nanoholes,femtosecond laser,amorphous silicon,metasurfaces,interference

    更新于2025-09-23 15:19:57

  • Operational Performance and Degradation Influenced Life Cycle Environmentala??Economic Metrics of mc-Si, a-Si and HIT Photovoltaic Arrays in Hot Semi-arid Climates

    摘要： Life cycle metrics evolution specific to the climate zone of photovoltaic (PV) operation would give detailed insights on the environmental and economic performance. At present, vast literature is available on the PV life cycle metrics where only the output energies ignoring the degradation rate (DR) influence. In this study, the environ-economic analysis of three PV technologies, namely, multi-crystalline silicon (mc-Si), amorphous silicon (a-Si) and hetero-junction with an intrinsic thin layer (HIT) have been carried out in identical environmental conditions. The energy performance parameters and the DR rate of three PV technologies are evaluated based on the monitored real time data from the installation site in hot semi-arid climates. The assessment demonstrates that the HIT PV module technology exhibits more suitable results compared to mc-Si and a-Si PV systems in hot semi-arid climatic conditions of India. Moreover, energy metrices which includes energy payback time (EPBT), energy production factor (EPF) and life cycle conversion efficiency (LCCE) of the HIT technologies are found to be 1.0, 24.93 and 0.15 years, respectively. HIT PV system has higher potential to mitigate the CO2 and carbon credit earned compared to mc-Si and a-Si PV system under hot semi-arid climate. However, the annualized uniform cost (UAC) for mc-Si (3.60 Rs/kWh) and a-Si (3.40 Rs/kWh) are more admissible in relation to the HIT (6.63 Rs/kWh) PV module type. We conclude that the approach of considering DR influenced life cycle metrics over the traditional approach can support to identify suitable locations for specific PV technology.

    关键词： annualized uniform cost,amorphous silicon,crystalline solar cells,life cycle assessment,PV cells,energy payback time,life cycle metrics,HIT,photovoltaic systems,degradation rate

    更新于2025-09-23 15:19:57

  • Trap-controlled space-charge-limited conduction in amorphous As <i> <sub/>x</sub></i> Te <sub/> 1a?? <i>x</i> </sub> thin films with ovonic threshold switching

    摘要： Ovonic threshold switching (OTS) in chalcogenide materials has attracted considerable interest for application in electronic devices to suppress leakage current in cross-point array structures. Although OTS appears to originate from an electronic process, the exact mechanism of OTS remains unclear with respect to sub-threshold conduction and threshold switching. In this study, we demonstrated that the sub-threshold conduction characteristics is affected by the structures of the exponentially distributed trap states in amorphous chalcogenide materials. Using binary AsxTe1?x thin films, we investigated the effects of trap distribution on OTS characteristics, analyzed the band structures, and developed a trap-controlled space-charge-limited conduction model.

    关键词： Ovonic threshold switching,space-charge-limited conduction,amorphous AsxTe1?x thin films,chalcogenide materials

    更新于2025-09-23 15:19:57

  • Lighting flicker: a blind spot in indoor photovoltaic cell characterization

    摘要： Pulse width modulation (PWM) driving is common in emerging solid-state or LED lighting. Unlike conventional lighting devices, the peak illumination intensity of a PWM-driven LED can be a hundredfold of average illumination intensity, causing strong lighting flicker. This work addresses the impact of the flicker on indoor amorphous Si (a-Si) photovoltaic cell performance. The power conversion efficiency of an amorphous silicon photovoltaic cell is found to be a function of not the average, but the peak illumination intensity. Indoor photovoltaic cells can thus seriously underperform under PWM-driven solid-state lighting when the peak illumination intensity is high enough to decrement photovoltaic cell performance.

    关键词： Lighting flicker,power conversion efficiency,amorphous silicon,indoor photovoltaic cell,PWM-driven LED

    更新于2025-09-23 15:19:57

  • Impact of laser treatment on hydrogenated amorphous silicon properties

    摘要： The application of laser radiation to locally modify the hydrogen distribution within hydrogenated amorphous silicon films on a short time scale is studied. The impact of laser power and irradiation time on the temperature of the silicon layer during the laser treatment and the hydrogen outdiffusion is analyzed. Moreover, the resulting optoelectronic properties of the amorphous silicon are examined. On a timescale of a few seconds or less, we can successfully decrease the hydrogen concentration in the surface-near region of the silicon layer without major impact on the optoelectronic properties.

    关键词： laser treatment,amorphous silicon,hydrogen diffusion

    更新于2025-09-23 15:19:57

  • AMORPHOUS/NANOCRYSTALLIZATION OF TiN-TiB <sub/>2</sub> REINFORCED LASER CLAD COMPOSITES

    摘要： Laser cladding (LC) of the Stellite6-BN-Cu-Y2O3 pre-placed powders on the Ti-6Al-4V alloy substrate formed the bulk TiN and needle-like Ti-B compounds reinforced composites, which improved the wear resistance of the substrate surface. The results showed that lots of the amorphous-nanocrystalline phases were produced in such composites; the proper content of Cu was used to reˉne microstructures, also a large number of the nanocrystals can be formed; the elements such as Co, Ni and Fe in Stellite6 favored the amorphous phase to be formed. The addition of Y2O3 improved the °uidity of the liquid metal, also retarding the growth of the dendrite, leading the ˉne microstructures to be formed, improving the property of the LC composites.

    关键词： nanocrystals,amorphous phase,surface modiˉcation,Laser cladding

    更新于2025-09-23 15:19:57

  • Two Birds with One Stone: Manipulating Colloids Assembled into Amorphous and Ordered Photonic Crystals and Their Combinations for Coding-Decoding

    摘要： Photonic crystals including amorphous and ordered photonic crystals (APCs and OPCs) show wide applications in color displays, sensors, and pigments. The fabrication of APCs and OPCs in one method is highly desired, however, it remains a big challenge due to the lack fine control the of the assemble behavior of the colloids. Herein, an efficient surface charge assisted colloidal assembly (SCACA) is developed to fabricate APCs with noniridescent structural colors and OPCs with iridescent colors by the co-assembly of aminated silica particles and nanosized carbon black (CB) in solution with different pH value. The surface charge of the particle is demonstrated to be the key to manipulate the assembly behavior of the particles, thus, the structure, defect, reflection intensity, and angle in/dependent structural color of the photonic crystals can be precisely controlled. Compared with previous strategies, SCACA is considerable simple and efficient in preparing APCs and OPCs which makes the fabrication more controllable, convenient and scalable. Moreover, through combing the noniridescent and iridescent structural colors of APCs and OPCs, a single color and multicolor based coding-decoding system are developed, in which the structural colors, numbers, positions, and angle in/dependency of codes can be hided and recognized by naked eyes at varied viewing angles. This work provides a new insight for precise manipulating the assembly of the colloids into APCs and OPCs, and extends their combined applications in anti-counterfeiting and information storage.

    关键词： Surface charge assisted colloidal assembly,Photonic crystals,Coding-decoding system,Ordered photonic crystals,Amorphous photonic crystals

    更新于2025-09-23 15:19:57

  • Corrosion wear and electrochemical corrosion behaviors of laser cladded amorphous FeSiB coating in 3.5% NaCl solution

    摘要： An amorphous FeSiB composite coating was fabricated on S355 structural steel using a laser cladding. The corrosion wear and electrochemical corrosion behaviors of FeSiB coating in 3.5% NaCl solution were investigated using a wear tester and electrochemical workstation. The results show that the FeSiB coating with the hardness of 601 HV is primarily composed of amorphous and crystal phases of α–Fe(Si) and Fe2B. The average coefficients of friction (COFs) of FeSiB coating at the wear loads of 3, 5 and 7 N loads are 0.888, 0.751, and 0.564, respectively, which deceases with the increase of wear loads; and the corresponding wear rates are 7.60, 8.02 and 10.04 μm3?N–1?m–1, respectively. The corrosion potentials of FeSiB coating and substrate are –0.718 and –1.042 V, respectively, exhibiting that the corrosion potential of FeSiB coating shifts positively, its corrosion resistance was higher than that of substrate.

    关键词： electrochemical corrosion,amorphous FeSiB composite coating,coefficient of friction (COF),wear mechanism,laser cladding (LC)

    更新于2025-09-23 15:19:57

  • Synthesis of high-purity zircon, zirconia, and silica nanopowders from local zircon sand

    摘要： High-purity zircon (ZrSiO4) nanopowder was successfully produced from Indonesian natural zircon sand using a low-cost purification approach via magnetic separation, immersion in HCl, and reaction with NaOH, followed by a top-down nanosizing process using wet ball-milling for 10 hours and annealing at 200 °C for 2 hours. Furthermore, polymorph zirconia (ZrO2 – amorphous, tetragonal, and monoclinic) and silica (SiO2 – amorphous and cristobalite) nanopowders were also successfully derived from the purified zircon powder using a bottom-up method via alkali fusion and co-precipitation processes followed by calcination. The crystallite size of the powders was estimated from X-ray diffraction (XRD) data analysis to give 40, 31, 61, and 149 nm, respectively, for the zircon, tetragonal- and monoclinic-zirconia, and cristobalite. Microstructural characteristics of the zircon, silica, and zirconia nanopowders were revealed in transmission electron microscopy (TEM) images which confirmed that the average sizes of the particles were in a good agreement with the XRD estimated values.

    关键词： zircon,tetragonal zirconia,amorphous silica,nanopowder,cristobalite,monoclinic zirconia

    更新于2025-09-23 15:19:57