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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
  • energy distribution
  • graphene edge
  • vacuum transistor
  • Field emission
应用领域
  • Optoelectronic Information Science and Engineering
机构单位
  • Naval Research Laboratory
  • KeyW Corporation
  • Pohang University of Science and Technology (POSTECH)
1443 条数据
?? 中文（中国） ▾

  • Tailoring chemical and physical properties of graphene-added DNA hybrid thin films

    摘要： While the characteristics of DNA and graphene are well studied, the chemical and physical properties of graphene-embedded DNA and cetyltrimethyl-ammonium chloride-modified DNA (CT-DNA) hybrid thin films (HTFs) have been rarely discussed due to the limited development of fabrication methodologies. Herein, we developed a simple drop-casting method for constructing DNA and CT-DNA HTFs added with graphene nanopowder (GNP). Additionally, we demonstrated their distinct characteristics, such as their structure, elemental composition, spin states and chemical functional groups, binding interactions, vibration/stretching modes, UV-Vis absorption, PL, and electrical properties. The EDS spectra of GNP-added DNA HTFs showed C, N, O, Na, and P peaks at characteristic energies. Because of the physical adsorption of GNP on DNA, the peak shifts and suppression of the core spectra of O 1s and P 2p were observed by XPS. The intensity variation of Raman and FTIR bands indicated hybrid formation of GNP in DNA and CT-DNA through adsorption, electrostatic interaction, and π–π stacking. UV-Vis absorption and PL spectra showed the considerable influence of GNP in DNA and CT-DNA HTFs. DNA and CT-DNA HTFs with relatively higher [GNP] showed significant increases of current due to the formation of interconnected networks of GNP in the DNA and CT-DNA HTFs.

    关键词： spectroscopy,DNA,electrical property,hybrid thin film,graphene

    更新于2025-09-04 15:30:14

  • Constructing excellent electromagnetic wave absorber with dielectric-dielectric media based on 3D reduced graphene and Ag(I)-Schiff base coordination compounds

    摘要： The dielectric-dielectric composite (SRGA) for electromagnetic absorber was fabricated via integrating Ag(I)-Schiff base coordination compounds (SSBCC) with three-dimensional reduced graphene aerogel (3D-rGA) powders. SRGA showed excellent electromagnetic wave absorption properties in terms of re?ection loss, absorption band width and absorber thickness. Specially, when the mass ratio of SSBC to 3D-rGA powders was 1:3 (SRGA-25), the maximum value of re?ection loss at 2 mm was up to (cid:1)63.82 dB and the effective frequency bandwidth of 6.28 GHz (10.16e16.44 GHz) at 2.5 mm can be obtained. The mechanism investigation of electromagnetic wave absorption for SRGA showed that the enhanced electromagnetic wave absorption was ascribed to enhanced polarization loss derived from good 3D-conductive-network units of 3D-rGA, abundant interfaces caused by the media heterostructure due to the introduction of SSBCC and the good impedance matching condition. And 3D-rGA based materials might be put into practical application only in powder state due to the very low strength of the buck state. Therefore, the investigation on SRGA in our contribution is considered to be an actual performance evaluation of the materials based on three-dimensional graphene for microwave attenuation. This work also provided a method for fabricating excellent graphene-based electromagnetic wave absorbers by simply mixing a suitable dielectric lossy material, e.g. SSBCC.

    关键词： Electromagnetic wave absorber,Schiff base,Composite,Microwave attenuation,Graphene aerogel

    更新于2025-09-04 15:30:14

  • Electron Transport in Nanoporous Graphene: Probing the Talbot Effect

    摘要： Electrons in graphene can show diffraction and interference phenomena fully analogous to light thanks to their Dirac-like energy dispersion. However, it is not clear how this optical analogy persists in nanostructured graphene, for example, with pores. Nanoporous graphene (NPG) consisting of linked graphene nanoribbons has recently been fabricated using molecular precursors and bottom-up assembly (Moreno et al. Science 2018, 360, 199). We predict that electrons propagating in NPG exhibit the interference Talbot effect, analogous to photons in coupled waveguides. Our results are obtained by parameter-free atomistic calculations of real-sized NPG samples based on seamlessly integrated density functional theory and tight-binding regions. We link the origins of this interference phenomenon to the band structure of the NPG. Most importantly, we demonstrate how the Talbot effect may be detected experimentally using dual-probe scanning tunneling microscopy. Talbot interference of electron waves in NPG or other related materials may open up new opportunities for future quantum electronics, computing, or sensing.

    关键词： multiscale modeling,electron transport,Nanoporous graphene,scanning probe microscopy,Talbot interference

    更新于2025-09-04 15:30:14

  • CMOS-compatible graphene

    摘要： Complementary metal–oxide–semiconductor (CMOS)-based integrated circuits use metal interconnect wires, which are made of aluminium and, more recently, copper, to provide electrical connections between the various circuit components. As technology node scaling has continued to fit more devices per square inch of silicon, interconnect wire cross-sections have needed to shrink, leading to increased resistivity, heating and electromigration issues. Recent investigations into the use of metals with higher melting points than copper, such as cobalt and ruthenium, have shown promising electromigration stability results, but their higher resistivities may limit their application to short local interconnects only. Similarly, attempts to use highly conductive graphene have so far been limited due to the need for high processing temperatures, which are incompatible with CMOS technologies. Kaustav Banerjee and colleagues at the University of California, Santa Barbara have now developed an approach to fabricate intercalation-doped graphene nanoribbon interconnects within the thermal constraints of CMOS technology processing. The method, which is based on a pressure-assisted solid-phase diffusion technique, brings the growth temperature down to 300 °C, and the researchers are able to demonstrate the fabrication of 20-nm-wide multilayer graphene interconnects on SiO2. The resistivity of the interconnects is less than that of metal interconnects with similar cross-sections, and the results suggest a four-fold reduction in circuit delay could be achieved if they were used as an alternative to cobalt- and ruthenium-based interconnects. Furthermore, stability and reliability analysis suggests an absence of any electromigration-related issues.

    关键词： interconnects,CMOS,resistivity,electromigration,graphene

    更新于2025-09-04 15:30:14

  • Highly transparent conductive reduced graphene oxide/silver nanowires/silver grid electrodes for low-voltage electrochromic smart windows

    摘要： Transparent conductive electrodes (TCEs) based on hybrid structures (silver nanowires) have been compressively reconnoitered in next-generation electronics such as flexible displays, artificial skins, smart windows, and sensors, owing to their admirable conductivity as well as flexibility, which make them favorable substitutes to replace ITO (Indium Tin Oxide) as a transparent conductor. Nevertheless, silver-based TCEs grieve from poor stability owing to the corrosion and oxidation of silver in electrolytes. To overcome these issues, a RGO (Reduced Graphene Oxide) layer on silver was promote to resolve the difficulties of corrosion and oxidation in the electrolyte. Moreover, we successfully designed and demonstrated low-voltage WO3-based electrochromic devices (ECDs) with fabricated hybrid TCEs. The hybrid electrodes with RGO/silver nanowires/metal grid/PET (RAM) electrode exhibited improvements in the switching stability and optoelectronic properties, such as the sheet resistance (0.714 ohm/sq), as well as optical transparency of 90.9%. The coloration and bleaching behavior of the ECD was observed in an applied low-voltage range of -1.0 to 0.0 V with a maximum optical difference of 72% at 700 nm, which yielded a coloration efficiency (η) of ~33.4 cm2/C. The highly conductive hybrid TCEs exhibit favorable features for numerous embryonic flexible electronics and optoelectronic devices.

    关键词： Oxidation,Silver nanowires,Electrochromic devices,Reduced graphene oxide,Corrosion

    更新于2025-09-04 15:30:14

  • Distinguishing Zigzag and Armchair Edges on Graphene Nanoribbons by X-ray Photoelectron and Raman Spectroscopies

    摘要： Graphene nanoribbons (GNRs) have recently emerged as alternative 2D semiconductors owing to their fascinating electronic properties that include tunable band gaps and high charge-carrier mobilities. Identifying the atomic-scale edge structures of GNRs through structural investigations is very important to fully understand the electronic properties of these materials. Herein, we report an atomic-scale analysis of GNRs using simulated X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Tetracene with zigzag edges and chrysene with armchair edges were selected as initial model structures, and their XPS and Raman spectra were analyzed. Structurally expanded nanoribbons based on tetracene and chrysene, in which zigzag and armchair edges were combined in various ratios, were then simulated. The edge structures of chain-shaped nanoribbons composed only of either zigzag edges or armchair edges were distinguishable by XPS and Raman spectroscopy, depending on the edge type. It was also possible to distinguish planar nanoribbons consisting of both zigzag and armchair edges with zigzag/armchair ratios of 4:1 or 1:4, indicating that it is possible to analyze normally synthesized GNRs because their zigzag to armchair edge ratios are usually greater than 4 or less than 0.25. Our study on the precise identification of GNR edge structures by XPS and Raman spectroscopy provides the groundwork for the analysis of GNRs.

    关键词： X-ray photoelectron spectroscopy,Graphene nanoribbons,armchair edges,zigzag edges,Raman spectroscopy

    更新于2025-09-04 15:30:14

  • Band Gap Control in Bilayer Graphene by Co-Doping with B-N Pairs

    摘要： The electronic band structure of bilayer graphene is studied systematically in the presence of substitutional B and/or N doping, using density functional theory with van der Waals correction. We show that introduction of B-N pairs into bilayer graphene can be used to create a substantial band gap, stable against thermal fluctuations at room temperature, but otherwise leaves the electronic band structure in the vicinity of the Fermi energy largely unaffected. Introduction of B-N pairs into B and/or N doped bilayer graphene likewise hardly modifies the band dispersions. In semiconducting systems (same amount of B and N dopants), however, the size of the band gap is effectively tuned in the presence of B-N pairs.

    关键词： density functional theory,van der Waals correction,band gap,B-N doping,bilayer graphene

    更新于2025-09-04 15:30:14

  • AIP Conference Proceedings [Author(s) INTERNATIONAL CONFERENCE ON SUSTAINABLE ENGINEERING AND TECHNOLOGY (ICONSET 2018) - Karnataka, India (19–20 April 2018)] - Synthesis of heterojunction layers of graphene/MoS2 and its characterization

    摘要： The synthesis of atomically thin layered MoS2/Graphene heterostructure is of great interest in optoelectronic devices because of their unique properties. Herein, we present a synthesis method to prepare heterostructure of MoS2/graphene using low pressure chemical vapor deposition. Atomic force microscopy, Raman spectra demonstrated that MoS2 film on graphene exhibited good thickness uniformity. This novel sensing structure based on a 2D heterostructure promises to provide a simple route to an essential sensing platform for wearable electronics.

    关键词： Heterojunction layer,Characterization,MoS2,Application,Graphene

    更新于2025-09-04 15:30:14

  • Enhanced absorption of graphene with variable bandwidth in quarter-wavelength cavities

    摘要： Quarter-wavelength cavity, as a classical structure for preventing wave re?ection, presents an effective way to enhance the interaction between light and material of ultrathin thickness. In this paper, we propose a method to control the bandwidth of graphene’s enhanced absorption in quarter-wavelength cavity. By varying the spacing distance between graphene and a metallic re?ecting plane, which equals to an odd number of quarter-wavelengths, fundamental and higher order cavity modes are excited, whose ?elds couple to graphene with different spectral bandwidths, leading to bandwidth-controllable absorption in graphene. Absorption ef?ciencies of 9% and 40% are measured for graphene monolayer at 15? and 85? incident angles, respectively. Its absorption bandwidth varies between 52% and 10% of the central wavelength when the spacing distance between graphene and metallic re?ecting plane increases from a quarter wavelength to seven quarter wavelengths. Our ?ndings pave a way in engineering graphene for strong absorption with a controllable bandwidth, which has potential applications in tailoring spectral response of graphene-based optoelectronic devices.

    关键词： quarter-wavelength cavity,bandwidth control,enhanced absorption,graphene

    更新于2025-09-04 15:30:14

  • Topologically Nontrivial Valley States in Bilayer Graphene Quantum Point Contacts

    摘要： We present measurements of quantized conductance in electrostatically induced quantum point contacts in bilayer graphene. The application of a perpendicular magnetic field leads to an intricate pattern of lifted and restored degeneracies with increasing field: at zero magnetic field the degeneracy of quantized one-dimensional subbands is four, because of a twofold spin and a twofold valley degeneracy. By switching on the magnetic field, the valley degeneracy is lifted. Because of the Berry curvature, states from different valleys split linearly in magnetic field. In the quantum Hall regime fourfold degenerate conductance plateaus reemerge. During the adiabatic transition to the quantum Hall regime, levels from one valley shift by two in quantum number with respect to the other valley, forming an interweaving pattern that can be reproduced by numerical calculations.

    关键词： quantum point contacts,quantized conductance,valley degeneracy,bilayer graphene,Berry curvature

    更新于2025-09-04 15:30:14